Dépouillements

Interplay between inertia and elasticity in film casting / Radoslav German in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 12 p. Titre : Interplay between inertia and elasticity in film casting Type de document : texte imprimé Auteurs : Radoslav German, Auteur ; Roger E. Khayat, Auteur Année de publication : 2009 Article en page(s) : 12 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Inertia  (mechanics);  stability;  flow  (dynamics);  elasticity;  fluids;  stress;  boundary-value  problems;  steady  state;  film  casting;  equations;  polymers;  fibers;  spin  (aerodynamics);  elongation Résumé : The influence of inertia and boundary conditions on the steady state and stability of isothermal film casting of viscoelastic fluids is examined using a Phan-Thien–Tanner rheological model. The elongational flow between the die exit and the take-up point is investigated. In general, the steady-state film tends to contract for low-inertia flow; this contraction, however, is significantly diminished by inertia. The polymeric normal stresses and primary normal stress difference decrease in the most of the air gap as inertia increases. In contrast, the stress and stress difference increase considerably near the take-up point due to a dramatic increase in the elongation rate. The linear stability analysis for two-dimensional disturbances is carried out. For a polymer with no degradation, and in the absence of inertia (Re=0), the analysis predicts critical draw ratios that form an envelope to an unstable region. This region of unstable conditions reduces as inertia increases. Two branches of neutral stability curve are observed for higher-inertia flow as opposed to a single curve for Re=0. The unstable region expands as α increases, where α is a measure of polymer degradation. When α becomes sufficiently large, the elasticity tends to destabilize the flow. It is also found that boundary conditions have an important influence on the steady-state profiles and stability region, particularly for high-elasticity fluids. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Interplay between inertia and elasticity in film casting [texte imprimé] / Radoslav German, Auteur ; Roger E. Khayat, Auteur . - 2009 . - 12 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 12 p. Mots-clés : Inertia  (mechanics);  stability;  flow  (dynamics);  elasticity;  fluids;  stress;  boundary-value  problems;  steady  state;  film  casting;  equations;  polymers;  fibers;  spin  (aerodynamics);  elongation Résumé : The influence of inertia and boundary conditions on the steady state and stability of isothermal film casting of viscoelastic fluids is examined using a Phan-Thien–Tanner rheological model. The elongational flow between the die exit and the take-up point is investigated. In general, the steady-state film tends to contract for low-inertia flow; this contraction, however, is significantly diminished by inertia. The polymeric normal stresses and primary normal stress difference decrease in the most of the air gap as inertia increases. In contrast, the stress and stress difference increase considerably near the take-up point due to a dramatic increase in the elongation rate. The linear stability analysis for two-dimensional disturbances is carried out. For a polymer with no degradation, and in the absence of inertia (Re=0), the analysis predicts critical draw ratios that form an envelope to an unstable region. This region of unstable conditions reduces as inertia increases. Two branches of neutral stability curve are observed for higher-inertia flow as opposed to a single curve for Re=0. The unstable region expands as α increases, where α is a measure of polymer degradation. When α becomes sufficiently large, the elasticity tends to destabilize the flow. It is also found that boundary conditions have an important influence on the steady-state profiles and stability region, particularly for high-elasticity fluids. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Confined swirling flows of aqueous surfactant solutions due to a rotating disk in a cylindrical casing / Shinji Tamano in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Titre : Confined swirling flows of aqueous surfactant solutions due to a rotating disk in a cylindrical casing Type de document : texte imprimé Auteurs : Shinji Tamano, Auteur ; Motoyuki Itoh, Auteur ; Mitsunori Yoshida, Auteur Année de publication : 2009 Article en page(s) : 9 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (dynamics);  elasticity;  fluids;  scillations;  Reynolds  number;  flow  visualization;  rotating  disks;  surfactants;  wirling  flow;  Laser  Doppler  anemometry;  rotation;  viscosity;  shear  (mechanics);  light  trucks Résumé : In this study, confined swirling flows of an aqueous surfactant solution due to a rotating disk in a cylindrical casing were investigated using a sectional flow visualization technique and a two-component laser Doppler velocimetry system. The concentrations of aqueous surfactant solutions (C14TASal) are 0.4wt%, 0.8wt%, and 1.2wt%. Rheological properties such as shear viscosity and first normal stress difference of the surfactant solution were measured with a rheometer. The patterns of secondary flow were classified using the Reynolds and elasticity numbers. We revealed that the projection formed near the center of the rotating disk moved up and down at a constant frequency for C14TASal0.8wt% and 1.2wt%, which has not been reported as far as we know. The effects of the Reynolds number, elasticity number, and aspect ratio on the velocity profiles were clarified. It was also found that the region of rigid body rotation existed at the higher Reynolds number tested for C14TASal0.4wt%. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Confined swirling flows of aqueous surfactant solutions due to a rotating disk in a cylindrical casing [texte imprimé] / Shinji Tamano, Auteur ; Motoyuki Itoh, Auteur ; Mitsunori Yoshida, Auteur . - 2009 . - 9 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Mots-clés : Flow  (dynamics);  elasticity;  fluids;  scillations;  Reynolds  number;  flow  visualization;  rotating  disks;  surfactants;  wirling  flow;  Laser  Doppler  anemometry;  rotation;  viscosity;  shear  (mechanics);  light  trucks Résumé : In this study, confined swirling flows of an aqueous surfactant solution due to a rotating disk in a cylindrical casing were investigated using a sectional flow visualization technique and a two-component laser Doppler velocimetry system. The concentrations of aqueous surfactant solutions (C14TASal) are 0.4wt%, 0.8wt%, and 1.2wt%. Rheological properties such as shear viscosity and first normal stress difference of the surfactant solution were measured with a rheometer. The patterns of secondary flow were classified using the Reynolds and elasticity numbers. We revealed that the projection formed near the center of the rotating disk moved up and down at a constant frequency for C14TASal0.8wt% and 1.2wt%, which has not been reported as far as we know. The effects of the Reynolds number, elasticity number, and aspect ratio on the velocity profiles were clarified. It was also found that the region of rigid body rotation existed at the higher Reynolds number tested for C14TASal0.4wt%. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Flow induced unstable structure of liquid crystalline polymer solution in L-shaped slit channels / Takatsune Narumi in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 6 p. Titre : Flow induced unstable structure of liquid crystalline polymer solution in L-shaped slit channels Type de document : texte imprimé Auteurs : Takatsune Narumi, Auteur ; Jun Fukada, Auteur ; Satoru Kiryu, Auteur Année de publication : 2009 Article en page(s) : 6 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (dynamics);  channels  (hydraulic  engineering);  corners  (structural  elements);  liquid  crystalline  polymers;  texture  (materials) Résumé : An experimental study has been conducted on unstable structures induced in two-dimensional slit flows of liquid crystalline polymer solution. 50wt% aqueous solution of hydroxyl-propylcellulose (HPC) was utilized as a test fluid and its flow behavior in L-shaped slit channels with a cross section of 1mm height and 16mm width was measured optically. The inner corner of the L-shaped channel was rounded off in order to clarify the influence of the radius of curvature on the unstable behavior. A conversing curved channel was also tested. The flow patterns of the HPC solution in the channels were visualized with two crossed polarizers and we observed that typical wavy textures generated in the upstream of the corner almost disappeared after the corner flow. However, an unstable texture was developed again only from the inner corner in downstream flow. The fluctuation of the orientation angle and dichroism were also measured with a laser opto-rheometric system and it was found that the unstable behaviors of the HPC solution have periodic oscillatory characteristics at a typical frequency. In the inner side flow after the corner, the periodic motion became larger toward the downstream and then higher harmonic oscillations were superimposed. Larger rounding off of the inner corner suppressed the redevelopment of unstable behavior, and it is considered that the rapid regrowth of unstable behavior was caused by rapid deceleration at the corner flow. Moreover, the unstable structure was stabilized with an accelerated (elongated) region in the corner flow and the converging channel was helpful to obtain a stable structure in the downstream region. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleID=1 [...] [article] Flow induced unstable structure of liquid crystalline polymer solution in L-shaped slit channels [texte imprimé] / Takatsune Narumi, Auteur ; Jun Fukada, Auteur ; Satoru Kiryu, Auteur . - 2009 . - 6 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 6 p. Mots-clés : Flow  (dynamics);  channels  (hydraulic  engineering);  corners  (structural  elements);  liquid  crystalline  polymers;  texture  (materials) Résumé : An experimental study has been conducted on unstable structures induced in two-dimensional slit flows of liquid crystalline polymer solution. 50wt% aqueous solution of hydroxyl-propylcellulose (HPC) was utilized as a test fluid and its flow behavior in L-shaped slit channels with a cross section of 1mm height and 16mm width was measured optically. The inner corner of the L-shaped channel was rounded off in order to clarify the influence of the radius of curvature on the unstable behavior. A conversing curved channel was also tested. The flow patterns of the HPC solution in the channels were visualized with two crossed polarizers and we observed that typical wavy textures generated in the upstream of the corner almost disappeared after the corner flow. However, an unstable texture was developed again only from the inner corner in downstream flow. The fluctuation of the orientation angle and dichroism were also measured with a laser opto-rheometric system and it was found that the unstable behaviors of the HPC solution have periodic oscillatory characteristics at a typical frequency. In the inner side flow after the corner, the periodic motion became larger toward the downstream and then higher harmonic oscillations were superimposed. Larger rounding off of the inner corner suppressed the redevelopment of unstable behavior, and it is considered that the rapid regrowth of unstable behavior was caused by rapid deceleration at the corner flow. Moreover, the unstable structure was stabilized with an accelerated (elongated) region in the corner flow and the converging channel was helpful to obtain a stable structure in the downstream region. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/article.aspx?articleID=1 [...]

Drop formation in non-newtonian jets at low Reynolds numbers / V. Dravid in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Titre : Drop formation in non-newtonian jets at low Reynolds numbers Type de document : texte imprimé Auteurs : V. Dravid, Auteur ; P. B. Loke, Auteur ; C. M. Corvalan, Auteur Année de publication : 2009 Article en page(s) : 8 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Drops;  shear  (mechanics);  jets;  atellites;  Reynolds  number;  pinch  effect  (plasma  physics);  equations;  water;  engineering  simulation;  pressure;  flow  (dynamics) Résumé : The objective of this study was to develop an experimentally verified computational model that accurately predicts evolution of shear-thinning liquid jets. A secondary objective was to investigate the formation of satellite drops and to determine conditions under which their diameter can be controlled. The model employs the Galerkin finite/element approach to solve the complete two-dimensional set of axisymmetric governing equations and the corresponding kinematic and dynamic boundary conditions at the free surface. The effect of shear-thinning behavior on breakup was studied in detail for the case of an infinitely long non-Newtonian jet. It was found that shear-thinning behavior may be useful in controlling satellite drop sizes. (We observe that increasing the shear-thinning behavior at Re∼5 leads to an initial increase in the satellite drop size, followed by a subsequent decrease.) Comparison of model predictions with experimental data is presented for the case of a shear-thinning non-Newtonian jet. The experimental liquid was pumped through a capillary and drop shapes obtained using a high speed camera. The experimentally obtained shapes were compared to those predicted by the model and found to be in good agreement. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Drop formation in non-newtonian jets at low Reynolds numbers [texte imprimé] / V. Dravid, Auteur ; P. B. Loke, Auteur ; C. M. Corvalan, Auteur . - 2009 . - 8 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Mots-clés : Drops;  shear  (mechanics);  jets;  atellites;  Reynolds  number;  pinch  effect  (plasma  physics);  equations;  water;  engineering  simulation;  pressure;  flow  (dynamics) Résumé : The objective of this study was to develop an experimentally verified computational model that accurately predicts evolution of shear-thinning liquid jets. A secondary objective was to investigate the formation of satellite drops and to determine conditions under which their diameter can be controlled. The model employs the Galerkin finite/element approach to solve the complete two-dimensional set of axisymmetric governing equations and the corresponding kinematic and dynamic boundary conditions at the free surface. The effect of shear-thinning behavior on breakup was studied in detail for the case of an infinitely long non-Newtonian jet. It was found that shear-thinning behavior may be useful in controlling satellite drop sizes. (We observe that increasing the shear-thinning behavior at Re∼5 leads to an initial increase in the satellite drop size, followed by a subsequent decrease.) Comparison of model predictions with experimental data is presented for the case of a shear-thinning non-Newtonian jet. The experimental liquid was pumped through a capillary and drop shapes obtained using a high speed camera. The experimentally obtained shapes were compared to those predicted by the model and found to be in good agreement. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Modeling and measurement of the dynamic surface tension of surfactant solutions / Tomiichi Hasegawa in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Titre : Modeling and measurement of the dynamic surface tension of surfactant solutions Type de document : texte imprimé Auteurs : Tomiichi Hasegawa, Auteur ; Masahiro Karasawa, Auteur ; Takatsune Narumi, Auteur Année de publication : 2009 Article en page(s) : 8 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Surface  tension;  equilibrium  (physics);  surfactants;  water;  modeling Résumé : Surfactant solutions are usually used under conditions accompanied by transient dynamic surfaces, and therefore the dynamic surface tension (DST) is important in many industrial processes. Theories regarding DST have been developed exclusively on the adsorption theory that molecules are transported from bulk solution to the interface. However, the adsorption theory is not closed and requires another relationship between the interfacial concentration of the adsorbing molecules and the bulk concentration of molecules near and at the surface, which at present is based on assumptions. In addition, DST obtained by the adsorption theory contains several parameters that must be determined beforehand, and it is not simple to use for practical purposes. Here, we propose a new model based on the concept that surfactant molecules rotate during the process reaching the equilibrium surface state, which is different from the conventional adsorption theory, and we obtained a simple expression of DST as a function of the surface age. In addition, an experiment was carried out to determine DST by measuring the period and weight of droplets falling from a capillary. The expression by the proposed model was compared with the results of this experiment and with those reported previously by several other authors, and good agreement was obtained. Furthermore, the characteristic time in the model was shown to be correlated with the concentrations of solutions regardless of the type of solutions examined. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Modeling and measurement of the dynamic surface tension of surfactant solutions [texte imprimé] / Tomiichi Hasegawa, Auteur ; Masahiro Karasawa, Auteur ; Takatsune Narumi, Auteur . - 2009 . - 8 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Mots-clés : Surface  tension;  equilibrium  (physics);  surfactants;  water;  modeling Résumé : Surfactant solutions are usually used under conditions accompanied by transient dynamic surfaces, and therefore the dynamic surface tension (DST) is important in many industrial processes. Theories regarding DST have been developed exclusively on the adsorption theory that molecules are transported from bulk solution to the interface. However, the adsorption theory is not closed and requires another relationship between the interfacial concentration of the adsorbing molecules and the bulk concentration of molecules near and at the surface, which at present is based on assumptions. In addition, DST obtained by the adsorption theory contains several parameters that must be determined beforehand, and it is not simple to use for practical purposes. Here, we propose a new model based on the concept that surfactant molecules rotate during the process reaching the equilibrium surface state, which is different from the conventional adsorption theory, and we obtained a simple expression of DST as a function of the surface age. In addition, an experiment was carried out to determine DST by measuring the period and weight of droplets falling from a capillary. The expression by the proposed model was compared with the results of this experiment and with those reported previously by several other authors, and good agreement was obtained. Furthermore, the characteristic time in the model was shown to be correlated with the concentrations of solutions regardless of the type of solutions examined. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Rheological and hydraulic properties of welan um fluids in straight and coiled tubings / Adedeji Asubiaro in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 16 p. Titre : Rheological and hydraulic properties of welan um fluids in straight and coiled tubings Type de document : texte imprimé Auteurs : Adedeji Asubiaro, Auteur ; Subhash N. Shah, Auteur Année de publication : 2009 Article en page(s) : 16 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (dynamics)  ;  friction;  fluids;  tubing Résumé : This study involves experimental investigation of the hydraulic characteristics of aqueous based welan gum fluids of concentrations 1.4kg∕m3, 2.9kg∕m3, 5.7kg∕m3, and 8.6kg∕m3 in both straight and coiled tubings at 21°C, with particular emphasis on the effect of polymer concentration and coiled tubing curvature ratio. The flow loop available at the Well Construction Technology Center of the University of Oklahoma, consisting of 1.27cm straight and coiled tubings (with curvature ratios of 0.01, 0.019, and 0.031), was utilized. It was observed that for all welan gum fluids investigated, friction losses in coiled tubing were significantly higher than those in straight tubing. In addition, increasing coiled tubing curvature ratio brings about higher friction loss for all fluids investigated. Rheological data for these fluids were obtained using a Model 35 Fann viscometer. Friction pressure data gathered from flow experiments are analyzed and correlations for friction pressure loss prediction of welan gum fluids have been developed for both straight and coiled tubings. These correlations, which represent the industry’s first attempt in the fundamental investigation of friction loss prediction of welan gum fluids, are found to provide good accuracy when compared to the experimental data. Flow behavior of welan gum fluids is compared with 4.9kg∕m3 guar fluid. It is found that in both straight and coiled tubings, the guar fluid exhibited higher drag reduction when compared to the welan gum fluids investigated in this study. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Rheological and hydraulic properties of welan um fluids in straight and coiled tubings [texte imprimé] / Adedeji Asubiaro, Auteur ; Subhash N. Shah, Auteur . - 2009 . - 16 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 16 p. Mots-clés : Flow  (dynamics)  ;  friction;  fluids;  tubing Résumé : This study involves experimental investigation of the hydraulic characteristics of aqueous based welan gum fluids of concentrations 1.4kg∕m3, 2.9kg∕m3, 5.7kg∕m3, and 8.6kg∕m3 in both straight and coiled tubings at 21°C, with particular emphasis on the effect of polymer concentration and coiled tubing curvature ratio. The flow loop available at the Well Construction Technology Center of the University of Oklahoma, consisting of 1.27cm straight and coiled tubings (with curvature ratios of 0.01, 0.019, and 0.031), was utilized. It was observed that for all welan gum fluids investigated, friction losses in coiled tubing were significantly higher than those in straight tubing. In addition, increasing coiled tubing curvature ratio brings about higher friction loss for all fluids investigated. Rheological data for these fluids were obtained using a Model 35 Fann viscometer. Friction pressure data gathered from flow experiments are analyzed and correlations for friction pressure loss prediction of welan gum fluids have been developed for both straight and coiled tubings. These correlations, which represent the industry’s first attempt in the fundamental investigation of friction loss prediction of welan gum fluids, are found to provide good accuracy when compared to the experimental data. Flow behavior of welan gum fluids is compared with 4.9kg∕m3 guar fluid. It is found that in both straight and coiled tubings, the guar fluid exhibited higher drag reduction when compared to the welan gum fluids investigated in this study. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Galerkin least-squares multifield approximations for flows of inelastic non-newtonian fluids / Flávia Zinani in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 14 p. Titre : Galerkin least-squares multifield approximations for flows of inelastic non-newtonian fluids Type de document : texte imprimé Auteurs : Flávia Zinani, Auteur ; Sérgio Frey, Auteur Année de publication : 2009 Article en page(s) : 14 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (dynamics);  fluids;  viscosity;  shear  (mechanics);  non-Newtonian  fluids;  finite  element  analysis;  approximation;  stress;  Reynolds  number;  pressure;  functions Résumé : The aim of this work is to investigate a Galerkin least-squares (GLS) multifield formulation for inelastic non-Newtonian fluid flows. We present the mechanical modeling of isochoric flows combining mass and momentum balance laws in continuum mechanics with an inelastic constitutive equation for the stress tensor. For the latter, we use the generalized Newtonian liquid model, which may predict either shear-thinning or shear-thickening. We employ a finite element formulation stabilized via a GLS scheme in three primal variables: extra stress, velocity, and pressure. This formulation keeps the inertial terms and has the capability of predicting viscosity dependency on the strain rate. The GLS method circumvents the compatibility conditions that arise in mixed formulations between the approximation functions of pressure and velocity and, in the multifield case, of extra stress and velocity. The GLS terms are added elementwise, as functions of the grid Reynolds number, so as to add artificial diffusivity selectively to diffusion and advection dominant flow regions—an important feature in the case of variable viscosity fluids. We present numerical results for the lid-driven cavity flow of shear-thinning and shear-thickening fluids, using the power-law viscosity function for Reynolds numbers between 50 and 500 and power-law exponents from 0.25 to 1.5. We also present results concerning flows of shear-thinning Carreau fluids through abrupt planar and axisymmetric contractions. We study ranges of Carreau numbers from 1 to 100, Reynolds numbers from 1 to 100, and power-law exponents equal to 0.1 and 0.5. Besides accounting for inertia effects in the flow, the GLS method captures some interesting features of shear-thinning flows, such as the reduction of the fluid stresses, the flattening of the velocity profile in the contraction plane, and the separation of the boundary layer downstream the contraction. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Galerkin least-squares multifield approximations for flows of inelastic non-newtonian fluids [texte imprimé] / Flávia Zinani, Auteur ; Sérgio Frey, Auteur . - 2009 . - 14 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 14 p. Mots-clés : Flow  (dynamics);  fluids;  viscosity;  shear  (mechanics);  non-Newtonian  fluids;  finite  element  analysis;  approximation;  stress;  Reynolds  number;  pressure;  functions Résumé : The aim of this work is to investigate a Galerkin least-squares (GLS) multifield formulation for inelastic non-Newtonian fluid flows. We present the mechanical modeling of isochoric flows combining mass and momentum balance laws in continuum mechanics with an inelastic constitutive equation for the stress tensor. For the latter, we use the generalized Newtonian liquid model, which may predict either shear-thinning or shear-thickening. We employ a finite element formulation stabilized via a GLS scheme in three primal variables: extra stress, velocity, and pressure. This formulation keeps the inertial terms and has the capability of predicting viscosity dependency on the strain rate. The GLS method circumvents the compatibility conditions that arise in mixed formulations between the approximation functions of pressure and velocity and, in the multifield case, of extra stress and velocity. The GLS terms are added elementwise, as functions of the grid Reynolds number, so as to add artificial diffusivity selectively to diffusion and advection dominant flow regions—an important feature in the case of variable viscosity fluids. We present numerical results for the lid-driven cavity flow of shear-thinning and shear-thickening fluids, using the power-law viscosity function for Reynolds numbers between 50 and 500 and power-law exponents from 0.25 to 1.5. We also present results concerning flows of shear-thinning Carreau fluids through abrupt planar and axisymmetric contractions. We study ranges of Carreau numbers from 1 to 100, Reynolds numbers from 1 to 100, and power-law exponents equal to 0.1 and 0.5. Besides accounting for inertia effects in the flow, the GLS method captures some interesting features of shear-thinning flows, such as the reduction of the fluid stresses, the flattening of the velocity profile in the contraction plane, and the separation of the boundary layer downstream the contraction. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Numerical and experimental study on metal organic vapor-phase epitaxy of InGaN∕GaN multi-quantum-wells / Changsung Sean Kim in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Titre : Numerical and experimental study on metal organic vapor-phase epitaxy of InGaN∕GaN multi-quantum-wells Type de document : texte imprimé Auteurs : Changsung Sean Kim, Auteur ; Jongpa Hong, Auteur ; Jihye Shim, Auteur Année de publication : 2009 Article en page(s) : 8 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Vapors;  metals;  wells;  semiconductor  wafers;  epitaxy;  surface  science;  temperature;  modeling;  temperature  distribution;  heating;  indium  gallium  nitride;  light-emitting  diodes;  computational  fluid  dynamics;  engineering  simulation;  equations;  measurement;  gallium  nitride;  rotation;  electromagnetic  induction;  databases Résumé : A numerical and experimental study has been performed to characterize the metal organic vapor-phase epitaxy (MOVPE) growth of InGaN∕GaN multi-quantum-wells. One of the major objectives of the present study is to predict the optimal operating conditions that would be suitable for the fabrication of GaN-based light-emitting diodes using three different reactors, vertical, horizontal, and planetary. Computational fluid dynamics (CFD) simulations considering gas-phase chemical reactions and surface chemistry were carried out and compared with experimental measurements. Through a lot of CFD simulations, the database for the multiparametric dependency of indium incorporation and growth rate in InGaN∕GaN layers has been established in a wide range of growth conditions. Also, a heating system using radio frequency power was verified to obtain the uniform temperature distribution by simulating the electromagnetic field as well as gas flow fields. The present multidisciplinary approach has been applied to the development of a novel-concept MOVPE system as well as performance enhancement of existing commercial reactors. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Numerical and experimental study on metal organic vapor-phase epitaxy of InGaN∕GaN multi-quantum-wells [texte imprimé] / Changsung Sean Kim, Auteur ; Jongpa Hong, Auteur ; Jihye Shim, Auteur . - 2009 . - 8 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Mots-clés : Vapors;  metals;  wells;  semiconductor  wafers;  epitaxy;  surface  science;  temperature;  modeling;  temperature  distribution;  heating;  indium  gallium  nitride;  light-emitting  diodes;  computational  fluid  dynamics;  engineering  simulation;  equations;  measurement;  gallium  nitride;  rotation;  electromagnetic  induction;  databases Résumé : A numerical and experimental study has been performed to characterize the metal organic vapor-phase epitaxy (MOVPE) growth of InGaN∕GaN multi-quantum-wells. One of the major objectives of the present study is to predict the optimal operating conditions that would be suitable for the fabrication of GaN-based light-emitting diodes using three different reactors, vertical, horizontal, and planetary. Computational fluid dynamics (CFD) simulations considering gas-phase chemical reactions and surface chemistry were carried out and compared with experimental measurements. Through a lot of CFD simulations, the database for the multiparametric dependency of indium incorporation and growth rate in InGaN∕GaN layers has been established in a wide range of growth conditions. Also, a heating system using radio frequency power was verified to obtain the uniform temperature distribution by simulating the electromagnetic field as well as gas flow fields. The present multidisciplinary approach has been applied to the development of a novel-concept MOVPE system as well as performance enhancement of existing commercial reactors. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Multiphysics simulation of electrochemical machining process for three-dimensional compressor blade / Toshiaki Fujisawa in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Titre : Multiphysics simulation of electrochemical machining process for three-dimensional compressor blade Type de document : texte imprimé Auteurs : Toshiaki Fujisawa, Auteur ; Kazuaki Inaba, Auteur ; Makoto Yamamoto, Auteur Année de publication : 2009 Article en page(s) : 8 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Metals;  machining;  compressors;  simulation;  bubbles;  blades;  flow  (dynamics);  flat  plates;  hydrogen;  electric  fields;  joules;  heating;  electrolytes;  equations;  electric  current Résumé : Electrochemical machining (ECM) is an advanced machining technology. It has been applied in highly specialized fields such as aerospace, aeronautics, and medical industries. However, it still has some problems to be overcome. The efficient tool design, electrolyte processing, and disposal of metal hydroxide sludge are the typical issues. To solve such problems, computational fluid dynamics is expected to be a powerful tool in the near future. However, a numerical method that can satisfactorily predict the electrolyte flow has not been established because of the complex nature of flows. In the present study, we developed a multiphysics model and the numerical procedure to predict the ECM process. Our model and numerical procedure satisfactorily simulated a typical ECM process for a two-dimensional flat plate. Next, the ECM process for a three-dimensional compressor blade was simulated. Through visualization of the computational results, including the multiphase flow, and thermal and electric fields between the tool and the blade, it is verified that the present model and numerical procedure could satisfactorily predict the final shape of the blade. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Multiphysics simulation of electrochemical machining process for three-dimensional compressor blade [texte imprimé] / Toshiaki Fujisawa, Auteur ; Kazuaki Inaba, Auteur ; Makoto Yamamoto, Auteur . - 2009 . - 8 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Mots-clés : Metals;  machining;  compressors;  simulation;  bubbles;  blades;  flow  (dynamics);  flat  plates;  hydrogen;  electric  fields;  joules;  heating;  electrolytes;  equations;  electric  current Résumé : Electrochemical machining (ECM) is an advanced machining technology. It has been applied in highly specialized fields such as aerospace, aeronautics, and medical industries. However, it still has some problems to be overcome. The efficient tool design, electrolyte processing, and disposal of metal hydroxide sludge are the typical issues. To solve such problems, computational fluid dynamics is expected to be a powerful tool in the near future. However, a numerical method that can satisfactorily predict the electrolyte flow has not been established because of the complex nature of flows. In the present study, we developed a multiphysics model and the numerical procedure to predict the ECM process. Our model and numerical procedure satisfactorily simulated a typical ECM process for a two-dimensional flat plate. Next, the ECM process for a three-dimensional compressor blade was simulated. Through visualization of the computational results, including the multiphase flow, and thermal and electric fields between the tool and the blade, it is verified that the present model and numerical procedure could satisfactorily predict the final shape of the blade. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Calculation of DEP and EWOD forces for application in digital microfluidics / Patrick M. Young in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Titre : Calculation of DEP and EWOD forces for application in digital microfluidics Type de document : texte imprimé Auteurs : Patrick M. Young, Auteur ; Kamran Mohseni, Auteur Année de publication : 2009 Article en page(s) : 9 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Force;  electrodes Résumé : Two primary methods for electrostatically actuating microdroplets in channels currently exist: dielectrophoresis (DEP) for electrically insulating fluids and electrowetting on dielectric (EWOD) for conducting fluids. In each case, a transverse electric field is used to create an electrostatic pressure, giving rise to the transport of individual liquid slugs. This paper examines the nature of the force distribution for both EWOD and DEP actuated droplets. The effects of system parameters such as contact angle and electrode length on the shape of the force density and its net integral are considered. A comparison of the scaling properties of DEP and EWOD for applications in digital microfluidics is presented. The net DEP force is shown to be strongly peaked when a droplet interface is located near the edge of a charged electrode and reduces to the well-known lumped parameter model in the appropriate limits. The effect of electrode spacing is seen to have an inversely proportional effect on the force experienced by the droplet, and the effect of increasing droplet contact angle is observed to increase the net force on the droplet. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Calculation of DEP and EWOD forces for application in digital microfluidics [texte imprimé] / Patrick M. Young, Auteur ; Kamran Mohseni, Auteur . - 2009 . - 9 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Mots-clés : Force;  electrodes Résumé : Two primary methods for electrostatically actuating microdroplets in channels currently exist: dielectrophoresis (DEP) for electrically insulating fluids and electrowetting on dielectric (EWOD) for conducting fluids. In each case, a transverse electric field is used to create an electrostatic pressure, giving rise to the transport of individual liquid slugs. This paper examines the nature of the force distribution for both EWOD and DEP actuated droplets. The effects of system parameters such as contact angle and electrode length on the shape of the force density and its net integral are considered. A comparison of the scaling properties of DEP and EWOD for applications in digital microfluidics is presented. The net DEP force is shown to be strongly peaked when a droplet interface is located near the edge of a charged electrode and reduces to the well-known lumped parameter model in the appropriate limits. The effect of electrode spacing is seen to have an inversely proportional effect on the force experienced by the droplet, and the effect of increasing droplet contact angle is observed to increase the net force on the droplet. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Optimization of high flow rate nanoporous electroosmotic pump / Y. Berrouche in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 7 p. Titre : Optimization of high flow rate nanoporous electroosmotic pump Type de document : texte imprimé Auteurs : Y. Berrouche, Auteur ; Y. Avenas, Auteur ; C. Schaeffer, Auteur Année de publication : 2009 Article en page(s) : 7 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Flow  (dynamics);  pumps Résumé : We present a theory for optimizing the thermodynamic efficiency of an electroosmotic (EO) pump with a large surface area highly charged nanoporous silica disk substrate. It was found that the optimum thermodynamic efficiency depends on the temperature, the silica zeta potential, the viscosity, the permittivity, the ion valency, the tortuosity of the nanoporous silica but mainly the effective normalized pore radius of the substrate scaled with respect to the Debye length. Using de-ionized water as the pumping liquid, the optimized EO pump generates a maximum flow rate of 13.6ml∕min at a pressure of 2kPa under an applied voltage of 150V. The power consumed by the pump is less than 0. 4W. The EO pump was designed to eliminate any bubble in the hydraulic circuit such that the pump can be operated continuously without significant degradation in the performance. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Optimization of high flow rate nanoporous electroosmotic pump [texte imprimé] / Y. Berrouche, Auteur ; Y. Avenas, Auteur ; C. Schaeffer, Auteur . - 2009 . - 7 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 7 p. Mots-clés : Flow  (dynamics);  pumps Résumé : We present a theory for optimizing the thermodynamic efficiency of an electroosmotic (EO) pump with a large surface area highly charged nanoporous silica disk substrate. It was found that the optimum thermodynamic efficiency depends on the temperature, the silica zeta potential, the viscosity, the permittivity, the ion valency, the tortuosity of the nanoporous silica but mainly the effective normalized pore radius of the substrate scaled with respect to the Debye length. Using de-ionized water as the pumping liquid, the optimized EO pump generates a maximum flow rate of 13.6ml∕min at a pressure of 2kPa under an applied voltage of 150V. The power consumed by the pump is less than 0. 4W. The EO pump was designed to eliminate any bubble in the hydraulic circuit such that the pump can be operated continuously without significant degradation in the performance. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

An analytical method for dielectrophoresis and traveling wave dielectrophoresis generated by an n-phase interdigitated parallel electrode array / Hongjun Song in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Titre : An analytical method for dielectrophoresis and traveling wave dielectrophoresis generated by an n-phase interdigitated parallel electrode array Type de document : texte imprimé Auteurs : Hongjun Song, Auteur ; Dawn J. Bennett, Auteur Année de publication : 2009 Article en page(s) : 8 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Force;  electric  fields;  waves;  electrodes;  boundary-value  problems;  travel;  electric  potential;  equations;  computational  fluid  dynamics Résumé : In this paper, we present an analytical method for solving the electric potential equation with the exact boundary condition. We analyze the dielectrophoresis (DEP) force with an n-phase ac electric field periodically applied on an interdigitated parallel electrode array. We compare our analytical solution with the numerical results obtained using the commercial software CFD-ACE . This software verifies that our analytical method is correct for solving the problem. In addition, we compare the analytical solutions obtained using the exact boundary conditions and the approximate boundary conditions. The comparison shows that the analytical solution with the exact boundary condition gives a more accurate analysis for DEP and traveling wave DEP forces. The DEP forces of latex beads are also investigated with different phase arrays for (n=2,3,4,5,6). En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] An analytical method for dielectrophoresis and traveling wave dielectrophoresis generated by an n-phase interdigitated parallel electrode array [texte imprimé] / Hongjun Song, Auteur ; Dawn J. Bennett, Auteur . - 2009 . - 8 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 8 p. Mots-clés : Force;  electric  fields;  waves;  electrodes;  boundary-value  problems;  travel;  electric  potential;  equations;  computational  fluid  dynamics Résumé : In this paper, we present an analytical method for solving the electric potential equation with the exact boundary condition. We analyze the dielectrophoresis (DEP) force with an n-phase ac electric field periodically applied on an interdigitated parallel electrode array. We compare our analytical solution with the numerical results obtained using the commercial software CFD-ACE . This software verifies that our analytical method is correct for solving the problem. In addition, we compare the analytical solutions obtained using the exact boundary conditions and the approximate boundary conditions. The comparison shows that the analytical solution with the exact boundary condition gives a more accurate analysis for DEP and traveling wave DEP forces. The DEP forces of latex beads are also investigated with different phase arrays for (n=2,3,4,5,6). En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist / Hidemasa Takana in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 7 p. Titre : Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist Type de document : texte imprimé Auteurs : Hidemasa Takana, Auteur ; Kazuhiro Ogawa, Auteur ; Tetsuo Shoji, Auteur Année de publication : 2009 Article en page(s) : 7 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Force;  flow  (dynamics);  particulate  matter;  simulation;  sprays;  flight;  coating  processes;  coatings;  shock  waves;  drag  (fluid  dynamics);  lift  (fluid  dynamics) Résumé : A real-time computational simulation on the entire cold spray process is carried out by the integrated model of compressible flow field, splat formation model, and coating formation model, in order to provide the fundamental data for the advanced high performance cold gas dynamic spray process with electrostatic acceleration. In this computation, viscous drag force, flow acceleration added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis, and electrostatic force are all considered in the particle equation of motion for the more realistic prediction of in-flight nano∕microparticle characteristics with electrostatic force and also for the detailed analysis of particle-shock-wave-substrate interaction. Computational results show that electrostatic acceleration can broaden the smallest size of applicable particle diameter for successful adhesion; as a result, wider coating can be realized. The utilization of electrostatic acceleration enhances the performance of cold dynamic spray process even under the presence of unavoidable shock wave. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Computational simulation on performance enhancement of cold gas dynamic spray processes with electrostatic assist [texte imprimé] / Hidemasa Takana, Auteur ; Kazuhiro Ogawa, Auteur ; Tetsuo Shoji, Auteur . - 2009 . - 7 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 7 p. Mots-clés : Force;  flow  (dynamics);  particulate  matter;  simulation;  sprays;  flight;  coating  processes;  coatings;  shock  waves;  drag  (fluid  dynamics);  lift  (fluid  dynamics) Résumé : A real-time computational simulation on the entire cold spray process is carried out by the integrated model of compressible flow field, splat formation model, and coating formation model, in order to provide the fundamental data for the advanced high performance cold gas dynamic spray process with electrostatic acceleration. In this computation, viscous drag force, flow acceleration added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis, and electrostatic force are all considered in the particle equation of motion for the more realistic prediction of in-flight nano∕microparticle characteristics with electrostatic force and also for the detailed analysis of particle-shock-wave-substrate interaction. Computational results show that electrostatic acceleration can broaden the smallest size of applicable particle diameter for successful adhesion; as a result, wider coating can be realized. The utilization of electrostatic acceleration enhances the performance of cold dynamic spray process even under the presence of unavoidable shock wave. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Dense particulate flow in a cold gas dynamic spray system / B. Samareh in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 11 p. Titre : Dense particulate flow in a cold gas dynamic spray system Type de document : texte imprimé Auteurs : B. Samareh, Auteur ; A. Dolatabadi, Auteur Année de publication : 2009 Article en page(s) : 11 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Pressure;  flow  (dynamics);  particulate  matter;  shock  (mechanics);  nozzles;  sprays Résumé : The effect of particle-gas and particle-particle interactions in a cold spray process is studied when the particle loading is high. To examine the effect of the presence of a dense particulate flow on the supersonic gas, an Eulerian-Eulerian approach is used. It is found that when the volume fraction of the injected particles is increased, the turbulence of the gas phase will be augmented by the motion of particles and consequently, the shape, the strength, and the location of the compression and expansion waves will be altered. Shock-particle interactions are demonstrated for various volume fractions. Another important parameter, which will affect the spraying deposition efficiency, is the substrate stand-off distance. It is found that the stagnation pressure alternates for different stand-off distances because of the formation of compression and expansion waves outside the nozzle exit. The particle normal velocity on impact is a strong function of the stagnation pressure on the substrate as particles must pierce through the bow shock formed on that region. The effect of the particle size and number density are also studied for different loading conditions. It is found that small and large particles behave differently as they pass through shock diamonds and the bow shock, i.e., in the case of very small particles, as the loading increases, the impact velocity increases, while, for the large particles, the trend is reversed. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Dense particulate flow in a cold gas dynamic spray system [texte imprimé] / B. Samareh, Auteur ; A. Dolatabadi, Auteur . - 2009 . - 11 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 11 p. Mots-clés : Pressure;  flow  (dynamics);  particulate  matter;  shock  (mechanics);  nozzles;  sprays Résumé : The effect of particle-gas and particle-particle interactions in a cold spray process is studied when the particle loading is high. To examine the effect of the presence of a dense particulate flow on the supersonic gas, an Eulerian-Eulerian approach is used. It is found that when the volume fraction of the injected particles is increased, the turbulence of the gas phase will be augmented by the motion of particles and consequently, the shape, the strength, and the location of the compression and expansion waves will be altered. Shock-particle interactions are demonstrated for various volume fractions. Another important parameter, which will affect the spraying deposition efficiency, is the substrate stand-off distance. It is found that the stagnation pressure alternates for different stand-off distances because of the formation of compression and expansion waves outside the nozzle exit. The particle normal velocity on impact is a strong function of the stagnation pressure on the substrate as particles must pierce through the bow shock formed on that region. The effect of the particle size and number density are also studied for different loading conditions. It is found that small and large particles behave differently as they pass through shock diamonds and the bow shock, i.e., in the case of very small particles, as the loading increases, the impact velocity increases, while, for the large particles, the trend is reversed. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

Soret effect for a ternary mixture in porous cavity / T. J. Jaber in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 8 (Août 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Titre : Soret effect for a ternary mixture in porous cavity : modeling with variable diffusion coefficients and viscosity Type de document : texte imprimé Auteurs : T. J. Jaber, Auteur ; Y. Yan, Auteur ; M. Z. Saghir, Auteur Année de publication : 2009 Article en page(s) : 9 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Diffusion  (physics);  permeability;  viscosity;  cavities;  thermal  diffusion;  temperature;  methane;  convection Résumé : A porous cavity filled with methane (C1), n-butane (nC4), and dodecane (C12) at a pressure of 35.0MPa is used to investigate numerically the flow interaction due to the presence of thermodiffusion and buoyancy forces. A lateral heating condition is applied with the left wall maintained at 10°C and the right wall at 50°C. The molecular diffusion and thermal diffusion coefficients are functions of temperature, concentration, and viscosity of mixture components. It has been found that for permeability below 200md the thermodiffusion is dominant; and above this level, buoyancy convection becomes the dominant mechanism. The variation of viscosity plays an important role on the molecular and thermal diffusion. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...] [article] Soret effect for a ternary mixture in porous cavity : modeling with variable diffusion coefficients and viscosity [texte imprimé] / T. J. Jaber, Auteur ; Y. Yan, Auteur ; M. Z. Saghir, Auteur . - 2009 . - 9 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 8 (Août 2008) . - 9 p. Mots-clés : Diffusion  (physics);  permeability;  viscosity;  cavities;  thermal  diffusion;  temperature;  methane;  convection Résumé : A porous cavity filled with methane (C1), n-butane (nC4), and dodecane (C12) at a pressure of 35.0MPa is used to investigate numerically the flow interaction due to the presence of thermodiffusion and buoyancy forces. A lateral heating condition is applied with the left wall maintained at 10°C and the right wall at 50°C. The molecular diffusion and thermal diffusion coefficients are functions of temperature, concentration, and viscosity of mixture components. It has been found that for permeability below 200md the thermodiffusion is dominant; and above this level, buoyancy convection becomes the dominant mechanism. The variation of viscosity plays an important role on the molecular and thermal diffusion. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/Issue.aspx?issueID=27329 [...]

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