Dépouillements

Scale-up correlation for the flow of surfactant-based fluids in circular coiled pipes / Ahmed H. Ahmed Kamel in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 12 p. Titre : Scale-up correlation for the flow of surfactant-based fluids in circular coiled pipes Type de document : texte imprimé Auteurs : Ahmed H. Ahmed Kamel, Auteur ; Subhash N. Shah, Auteur Année de publication : 2010 Article en page(s) : 12 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  friction;  fluids;  tubing;  pipes;  surfactants Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study involves experimental investigation on the flow properties of aqueous surfactant-based (SB) fluids in small and large-scale coiled tubing. It aims at understanding the viscoelastic properties and its effect on the flow behavior of SB fluids in coiled tubing. In spite of SB fluids wide use as friction reducer and/or fracturing fluid in the oil and gas industry, the flow data in large pipe sizes as well as coiled tubing are very scarce. Majority of the available flow data are gathered in straight pipes with small sizes. The scale-up of small-scale flow data is questionable due to the pronounced diameter effect. Furthermore, previous studies have correlated flow behavior of these fluids only through simple power-law model parameters. Limited work with polymeric fluids has been reported that includes fluid elasticity in scale-up procedure and it is nonexistent for highly elastic SB fluids. In this study, the properties of widely used Aromox APA-T, a highly active surfactant used as gelling agent in aqueous and brine base fluids, are thoroughly investigated. Rheological measurements are conducted using Bohlin rheometer for SB fluid concentration of 1.5 vol %, 2 vol %, 3 vol %, and 4 vol %. Flow data are gathered using 1.27 cm, 3.81 cm, 6.03 cm, and 7.30 cm OD coiled tubing with various curvature ratios. This study presents the first attempt to investigate the flow behavior SB fluids in large-scale coiled tubing. The results show that SB fluids exhibit non-Newtonian pseudoplastic behavior. Elastic and viscous properties of SB fluids are very sensitive to surfactant concentration. Friction losses in coiled tubing are significantly higher than those in straight pipes due to secondary flow effect. Increasing curvature ratio yields higher friction pressure loss. Also, small-scale data correlations using only simple power-law model fluid rheological parameters lead to erroneous results when scaled-up to large pipe sizes. New technique, based on the modified Deborah number, which includes fluid elasticity and pipe shear effect, has been developed to correlate data from the small laboratory-scale tubing and large field-scale pipes. Correlation to predict Fanning friction factor of SB fluids in coiled tubing as a function of Deborah number and fluid flow behavior index is presented. Correlation is validated by comparing predictions with the experimental data. It is shown that the new correlation accurately predicts friction factor of SB fluids and thus alleviates the scale-up issue. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Scale-up correlation for the flow of surfactant-based fluids in circular coiled pipes [texte imprimé] / Ahmed H. Ahmed Kamel, Auteur ; Subhash N. Shah, Auteur . - 2010 . - 12 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 12 p. Mots-clés : flow  (dynamics);  friction;  fluids;  tubing;  pipes;  surfactants Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This study involves experimental investigation on the flow properties of aqueous surfactant-based (SB) fluids in small and large-scale coiled tubing. It aims at understanding the viscoelastic properties and its effect on the flow behavior of SB fluids in coiled tubing. In spite of SB fluids wide use as friction reducer and/or fracturing fluid in the oil and gas industry, the flow data in large pipe sizes as well as coiled tubing are very scarce. Majority of the available flow data are gathered in straight pipes with small sizes. The scale-up of small-scale flow data is questionable due to the pronounced diameter effect. Furthermore, previous studies have correlated flow behavior of these fluids only through simple power-law model parameters. Limited work with polymeric fluids has been reported that includes fluid elasticity in scale-up procedure and it is nonexistent for highly elastic SB fluids. In this study, the properties of widely used Aromox APA-T, a highly active surfactant used as gelling agent in aqueous and brine base fluids, are thoroughly investigated. Rheological measurements are conducted using Bohlin rheometer for SB fluid concentration of 1.5 vol %, 2 vol %, 3 vol %, and 4 vol %. Flow data are gathered using 1.27 cm, 3.81 cm, 6.03 cm, and 7.30 cm OD coiled tubing with various curvature ratios. This study presents the first attempt to investigate the flow behavior SB fluids in large-scale coiled tubing. The results show that SB fluids exhibit non-Newtonian pseudoplastic behavior. Elastic and viscous properties of SB fluids are very sensitive to surfactant concentration. Friction losses in coiled tubing are significantly higher than those in straight pipes due to secondary flow effect. Increasing curvature ratio yields higher friction pressure loss. Also, small-scale data correlations using only simple power-law model fluid rheological parameters lead to erroneous results when scaled-up to large pipe sizes. New technique, based on the modified Deborah number, which includes fluid elasticity and pipe shear effect, has been developed to correlate data from the small laboratory-scale tubing and large field-scale pipes. Correlation to predict Fanning friction factor of SB fluids in coiled tubing as a function of Deborah number and fluid flow behavior index is presented. Correlation is validated by comparing predictions with the experimental data. It is shown that the new correlation accurately predicts friction factor of SB fluids and thus alleviates the scale-up issue. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Numerical simulation of the transient flow in a centrifugal pump during starting period / Zhifeng Li in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 08 p. Titre : Numerical simulation of the transient flow in a centrifugal pump during starting period Type de document : texte imprimé Auteurs : Zhifeng Li, Auteur ; Dazhuan Wu, Auteur ; Leqin Wang, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  computer  simulation;  impellers;  pumps;  blades;  centrifugal  pumps Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Computational fluid dynamics were used to study the three-dimensional unsteady incompressible viscous flows in a centrifugal pump during rapid starting period (≈0.12 s). The rotational speed variation of the field around the impeller was realized by a dynamic slip region method, which combines the dynamic mesh method with nonconformal grid boundaries. In order to avoid introducing errors brought by the externally specified unsteady inlet and outlet boundary conditions, a physical model composed of a pipe system and pump was developed for numerical self-coupling computation. The proposed method makes the computation processes more close to the real conditions. Relations between the instantaneous flow evolutions and the corresponding transient flow-rate, head, efficiency and power were analyzed. Relative velocity comparisons between the transient and the corresponding quasisteady results were discussed. Observations of the formations and evolutions of the primary vortices filled between the startup blades illustrate the features of the transient internal flow. The computational transient performances qualitatively agree with published data, indicating that the present method is capable of solving unsteady flow in a centrifugal pump under transient operations. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Numerical simulation of the transient flow in a centrifugal pump during starting period [texte imprimé] / Zhifeng Li, Auteur ; Dazhuan Wu, Auteur ; Leqin Wang, Auteur . - 2010 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 08 p. Mots-clés : flow  (dynamics);  computer  simulation;  impellers;  pumps;  blades;  centrifugal  pumps Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Computational fluid dynamics were used to study the three-dimensional unsteady incompressible viscous flows in a centrifugal pump during rapid starting period (≈0.12 s). The rotational speed variation of the field around the impeller was realized by a dynamic slip region method, which combines the dynamic mesh method with nonconformal grid boundaries. In order to avoid introducing errors brought by the externally specified unsteady inlet and outlet boundary conditions, a physical model composed of a pipe system and pump was developed for numerical self-coupling computation. The proposed method makes the computation processes more close to the real conditions. Relations between the instantaneous flow evolutions and the corresponding transient flow-rate, head, efficiency and power were analyzed. Relative velocity comparisons between the transient and the corresponding quasisteady results were discussed. Observations of the formations and evolutions of the primary vortices filled between the startup blades illustrate the features of the transient internal flow. The computational transient performances qualitatively agree with published data, indicating that the present method is capable of solving unsteady flow in a centrifugal pump under transient operations. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Patterns of airflow in circular tubes caused by a corona jet with concentric and eccentric wire electrodes / Reza Baghaei Lakeh in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 10 p. Titre : Patterns of airflow in circular tubes caused by a corona jet with concentric and eccentric wire electrodes Type de document : texte imprimé Auteurs : Reza Baghaei Lakeh, Auteur ; Majid Molki, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : force;  flow  (dynamics);  electric  fields;  air  flow;  wire;  electrohydrodynamics;  electrodes;  computation;  equations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A computational investigation is conducted to study the patterns of airflow induced by corona discharge in the cross section of a circular tube. The secondary flow induced by corona wind in various flow passages has been the subject of numerous investigations. The flow patterns are often identified by multiple recirculation bubbles. Such flow patterns have also been anticipated for circular cross sections where the corona discharge is activated by an electrode situated at the center of the cross section. In this investigation, it is shown that, contrary to public perception, a symmetric corona discharge does not generate a secondary flow in circular cross sections. This investigation then proceeds to demonstrate that the flow responsible for thermal enhancements in circular tubes often reported in the published literature is induced only when there is a slight asymmetry in the position of the electrode. The present computations are performed in two parts. In part one, the electric field equations are solved using the method of characteristics. In part two, the flow equations are solved using a finite-volume method. It is shown that the method of characteristics effectively eliminates the dispersion errors observed in other numerical solutions. The present computations show that the flow in the eccentric configuration is characterized by a corona jet that is oriented along the eccentricity direction and two recirculation zones situated on either sides of the jet. In addition to the computational approach, a number of analytical solutions are presented and compared with the computational results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Patterns of airflow in circular tubes caused by a corona jet with concentric and eccentric wire electrodes [texte imprimé] / Reza Baghaei Lakeh, Auteur ; Majid Molki, Auteur . - 2010 . - 10 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 10 p. Mots-clés : force;  flow  (dynamics);  electric  fields;  air  flow;  wire;  electrohydrodynamics;  electrodes;  computation;  equations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A computational investigation is conducted to study the patterns of airflow induced by corona discharge in the cross section of a circular tube. The secondary flow induced by corona wind in various flow passages has been the subject of numerous investigations. The flow patterns are often identified by multiple recirculation bubbles. Such flow patterns have also been anticipated for circular cross sections where the corona discharge is activated by an electrode situated at the center of the cross section. In this investigation, it is shown that, contrary to public perception, a symmetric corona discharge does not generate a secondary flow in circular cross sections. This investigation then proceeds to demonstrate that the flow responsible for thermal enhancements in circular tubes often reported in the published literature is induced only when there is a slight asymmetry in the position of the electrode. The present computations are performed in two parts. In part one, the electric field equations are solved using the method of characteristics. In part two, the flow equations are solved using a finite-volume method. It is shown that the method of characteristics effectively eliminates the dispersion errors observed in other numerical solutions. The present computations show that the flow in the eccentric configuration is characterized by a corona jet that is oriented along the eccentricity direction and two recirculation zones situated on either sides of the jet. In addition to the computational approach, a number of analytical solutions are presented and compared with the computational results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Mass transfer in a rigid tube with pulsatile flow and constant wall concentration / T. E. Moschandreou in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 11 p. Titre : Mass transfer in a rigid tube with pulsatile flow and constant wall concentration Type de document : texte imprimé Auteurs : T. E. Moschandreou, Auteur ; C. G. Ellis, Auteur ; D. Goldman, Auteur Année de publication : 2010 Article en page(s) : 11 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  diffusion  (physics);  mass  transfer;  fluctuations  (physics);  differential  equations;  cycles;  equations;  frequency;  pulsatile  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An approximate-analytical solution method is presented for the problem of mass transfer in a rigid tube with pulsatile flow. For the case of constant wall concentration, it is shown that the generalized integral transform (GIT) method can be used to obtain a solution in terms of a perturbation expansion, where the coefficients of each term are given by a system of coupled ordinary differential equations. Truncating the system at some large value of the parameter N, an approximate solution for the system is obtained for the first term in the perturbation expansion, and the GIT-based solution is verified by comparison to a numerical solution. The GIT approximate-analytical solution indicates that for small to moderate nondimensional frequencies for any distance from the inlet of the tube, there is a positive peak in the bulk concentration C1b due to pulsation, thereby, producing a higher mass transfer mixing efficiency in the tube. As we further increase the frequency, the positive peak is followed by a negative peak in the time-averaged bulk concentration and then the bulk concentration C1b oscillates and dampens to zero. Initially, for small frequencies the relative Sherwood number is negative indicating that the effect of pulsation tends to reduce mass transfer. There is a band of frequencies, where the relative Sherwood number is positive indicating that the effect of pulsation tends to increase mass transfer. The positive peak in bulk concentration corresponds to a matching of the phase of the pulsatile velocity and the concentration, respectively, where the unique maximum of both occur for certain time in the cycle. The oscillatory component of concentration is also determined radially in the tube where the concentration develops first near the wall of the tube, and the lobes of the concentration curves increase with increasing distance downstream until the concentration becomes fully developed. The GIT method proves to be a working approach to solve the first two perturbation terms in the governing equations involved. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Mass transfer in a rigid tube with pulsatile flow and constant wall concentration [texte imprimé] / T. E. Moschandreou, Auteur ; C. G. Ellis, Auteur ; D. Goldman, Auteur . - 2010 . - 11 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 11 p. Mots-clés : flow  (dynamics);  diffusion  (physics);  mass  transfer;  fluctuations  (physics);  differential  equations;  cycles;  equations;  frequency;  pulsatile  flow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : An approximate-analytical solution method is presented for the problem of mass transfer in a rigid tube with pulsatile flow. For the case of constant wall concentration, it is shown that the generalized integral transform (GIT) method can be used to obtain a solution in terms of a perturbation expansion, where the coefficients of each term are given by a system of coupled ordinary differential equations. Truncating the system at some large value of the parameter N, an approximate solution for the system is obtained for the first term in the perturbation expansion, and the GIT-based solution is verified by comparison to a numerical solution. The GIT approximate-analytical solution indicates that for small to moderate nondimensional frequencies for any distance from the inlet of the tube, there is a positive peak in the bulk concentration C1b due to pulsation, thereby, producing a higher mass transfer mixing efficiency in the tube. As we further increase the frequency, the positive peak is followed by a negative peak in the time-averaged bulk concentration and then the bulk concentration C1b oscillates and dampens to zero. Initially, for small frequencies the relative Sherwood number is negative indicating that the effect of pulsation tends to reduce mass transfer. There is a band of frequencies, where the relative Sherwood number is positive indicating that the effect of pulsation tends to increase mass transfer. The positive peak in bulk concentration corresponds to a matching of the phase of the pulsatile velocity and the concentration, respectively, where the unique maximum of both occur for certain time in the cycle. The oscillatory component of concentration is also determined radially in the tube where the concentration develops first near the wall of the tube, and the lobes of the concentration curves increase with increasing distance downstream until the concentration becomes fully developed. The GIT method proves to be a working approach to solve the first two perturbation terms in the governing equations involved. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Numerical modeling and analysis of entrainment in turbulent jets after the end of injection / Satbir Singh in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 10 p. Titre : Numerical modeling and analysis of entrainment in turbulent jets after the end of injection Type de document : texte imprimé Auteurs : Satbir Singh, Auteur ; Mark P. B. Musculus, Auteur Année de publication : 2010 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : momentum;  flow  (dynamics);  fluids;  measurement;  turbulence;  waves;  jets;  computational  fluid  dynamics;  nozzles;  equations;  mixtures Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Previous velocity and scalar measurements in both single-phase jets and two-phase diesel fuel sprays indicate that after the flow at the nozzle decelerates, ambient-gas entrainment increases compared to a steady jet. Previous studies using simplified analytical models and computational fluid dynamics (CFD) simulations using a one-dimensional (1D) inviscid, incompressible momentum equation have predicted that an “entrainment wave” propagates downstream along the jet axis during and after the deceleration, increasing entrainment by up to a factor of 3. In this study, entrainment is analyzed using the full compressible, unsteady Navier–Stokes momentum equations in axisymmetric two-dimensional (2D) CFD simulations of single-pulsed transient round gas jets. The 2D simulations confirm the existence of the entrainment wave, although the region of increased entrainment is distributed over a wider axial region of the jet than predicted by the simplified 1D model, so that the peak entrainment rate increases by only 50% rather than by a factor of 3. In the long time limit, both models show that the rate of mixing relative to the local injected fluid concentration increases significantly, approaching a factor of 3 or more increase in the wake of the entrainment wave (relative to a steady jet). Analysis of the terms in the momentum equation shows that the entrainment wave in the full 2D CFD predictions occurs in two phases. The entrainment first increases slightly due to a radial pressure gradient induced by a relatively fast acoustic wave, which the simple 1D model does not account for. The acoustic wave is followed by a slower momentum wave of decreased axial velocity initiated at the nozzle, which is convected downstream at the local flow velocities. The largest increase in entrainment accompanies the momentum wave, which is captured by the 1D momentum-equation model. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Numerical modeling and analysis of entrainment in turbulent jets after the end of injection [texte imprimé] / Satbir Singh, Auteur ; Mark P. B. Musculus, Auteur . - 2010 . - 10 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 10 p. Mots-clés : momentum;  flow  (dynamics);  fluids;  measurement;  turbulence;  waves;  jets;  computational  fluid  dynamics;  nozzles;  equations;  mixtures Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Previous velocity and scalar measurements in both single-phase jets and two-phase diesel fuel sprays indicate that after the flow at the nozzle decelerates, ambient-gas entrainment increases compared to a steady jet. Previous studies using simplified analytical models and computational fluid dynamics (CFD) simulations using a one-dimensional (1D) inviscid, incompressible momentum equation have predicted that an “entrainment wave” propagates downstream along the jet axis during and after the deceleration, increasing entrainment by up to a factor of 3. In this study, entrainment is analyzed using the full compressible, unsteady Navier–Stokes momentum equations in axisymmetric two-dimensional (2D) CFD simulations of single-pulsed transient round gas jets. The 2D simulations confirm the existence of the entrainment wave, although the region of increased entrainment is distributed over a wider axial region of the jet than predicted by the simplified 1D model, so that the peak entrainment rate increases by only 50% rather than by a factor of 3. In the long time limit, both models show that the rate of mixing relative to the local injected fluid concentration increases significantly, approaching a factor of 3 or more increase in the wake of the entrainment wave (relative to a steady jet). Analysis of the terms in the momentum equation shows that the entrainment wave in the full 2D CFD predictions occurs in two phases. The entrainment first increases slightly due to a radial pressure gradient induced by a relatively fast acoustic wave, which the simple 1D model does not account for. The acoustic wave is followed by a slower momentum wave of decreased axial velocity initiated at the nozzle, which is convected downstream at the local flow velocities. The largest increase in entrainment accompanies the momentum wave, which is captured by the 1D momentum-equation model. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

The peak overpressure field resulting from shocks emerging from circular shock tubes / A. J. Newman in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 07 p. Titre : The peak overpressure field resulting from shocks emerging from circular shock tubes Type de document : texte imprimé Auteurs : A. J. Newman, Auteur ; J. C. Mollendorf, Auteur Année de publication : 2010 Article en page(s) : 07 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : measurement;  shock  (mechanics);  equations;  shapes;  shock  tubes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A simple semi-empirical model for predicting the peak overpressure field that results when a shock emerges from a circular shock tube is presented and validated. By assuming that the shape of the expanding shock remains geometrically similar after an initial development period, an equation that describes the peak overpressure field in the horizontal plane containing the shock tube’s centerline was developed. The accuracy of this equation was evaluated experimentally by collecting peak overpressure field measurements along radials from the shock tube exit at 0 deg, 45 deg, and 90 deg over a range of shock Mach numbers from 1.15 to 1.45. It was found that the equation became more accurate at higher Mach numbers with percent differences between experimental measurements and theoretical predictions ranging from 1.1% to 3.6% over the range of Mach numbers considered. (1) Shocks do propagate in a geometrically similar manner after some initial development length over the range of Mach numbers considered here. (2) The model developed here gives reasonable predictions for the overpressure field from a shock emerging from a circular shock tube. (3) Shocks are expected to be completely symmetric with respect to the shock tube’s centerline, and hence, a three dimensional overpressure field may be predicted by the model developed here. (4) While there is a range of polar angle at which the shock shape may be described as being spherical with respect to the shock tube’s exit, this range does not encompass the entirety of the half space in front of the shock tube, and the model developed here is needed to accurately describe the entire peak overpressure field. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] The peak overpressure field resulting from shocks emerging from circular shock tubes [texte imprimé] / A. J. Newman, Auteur ; J. C. Mollendorf, Auteur . - 2010 . - 07 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 07 p. Mots-clés : measurement;  shock  (mechanics);  equations;  shapes;  shock  tubes Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : A simple semi-empirical model for predicting the peak overpressure field that results when a shock emerges from a circular shock tube is presented and validated. By assuming that the shape of the expanding shock remains geometrically similar after an initial development period, an equation that describes the peak overpressure field in the horizontal plane containing the shock tube’s centerline was developed. The accuracy of this equation was evaluated experimentally by collecting peak overpressure field measurements along radials from the shock tube exit at 0 deg, 45 deg, and 90 deg over a range of shock Mach numbers from 1.15 to 1.45. It was found that the equation became more accurate at higher Mach numbers with percent differences between experimental measurements and theoretical predictions ranging from 1.1% to 3.6% over the range of Mach numbers considered. (1) Shocks do propagate in a geometrically similar manner after some initial development length over the range of Mach numbers considered here. (2) The model developed here gives reasonable predictions for the overpressure field from a shock emerging from a circular shock tube. (3) Shocks are expected to be completely symmetric with respect to the shock tube’s centerline, and hence, a three dimensional overpressure field may be predicted by the model developed here. (4) While there is a range of polar angle at which the shock shape may be described as being spherical with respect to the shock tube’s exit, this range does not encompass the entirety of the half space in front of the shock tube, and the model developed here is needed to accurately describe the entire peak overpressure field. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Developing laminar gravity-driven thin liquid film flow down an inclined plane / H. Lan in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 08 p. Titre : Developing laminar gravity-driven thin liquid film flow down an inclined plane Type de document : texte imprimé Auteurs : H. Lan, Auteur ; J. L. Wegener, Auteur ; B. F. Armaly, Auteur Année de publication : 2010 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : gravity  (force);  surface  tension;  flow  (dynamics);  measurement;  instrumentation;  film  flow;  film  thickness;  liquid  films;  lubrication  theory Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional (3D)—steady-developing-laminar-isothermal—and gravity-driven thin liquid film flow adjacent to an inclined plane is examined and the effects of film flow rate, surface tension, and surface inclination angle on the film thickness and film width are presented. The film flow was numerically simulated using the volume of fluid model and experimental verification was conducted by measuring film thickness and width using a laser focus displacement instrument. The steady film flow that is considered in this study does not have a leading contact line, however, it has two steady side contact lines with the substrate surface at the outer edge of its width. Results reveal that the film width decreases and the average film thickness increases as the film flows down the inclined plane. The film thickness and width decrease but its streamwise velocity increases as surface inclination angle (as measured from the horizontal plane) increases. A higher film flow rate is associated with a higher film thickness, a higher film width, and a higher average film velocity. Films with higher surface tension are associated with a smaller width and a higher average thickness. A ripple develops near the side contact line, i.e., the spanwise distribution of the film thickness exhibits peaks at the outer edges of the film width and the height of this ripple increases as the surface tension or the film flow rate increases. The width of the film decreases at a faster rate along the streamwise direction if liquid film has higher surface tension. Measurements of the film thickness and the film width compare favorably with the numerically simulated results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Developing laminar gravity-driven thin liquid film flow down an inclined plane [texte imprimé] / H. Lan, Auteur ; J. L. Wegener, Auteur ; B. F. Armaly, Auteur . - 2010 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 08 p. Mots-clés : gravity  (force);  surface  tension;  flow  (dynamics);  measurement;  instrumentation;  film  flow;  film  thickness;  liquid  films;  lubrication  theory Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Three-dimensional (3D)—steady-developing-laminar-isothermal—and gravity-driven thin liquid film flow adjacent to an inclined plane is examined and the effects of film flow rate, surface tension, and surface inclination angle on the film thickness and film width are presented. The film flow was numerically simulated using the volume of fluid model and experimental verification was conducted by measuring film thickness and width using a laser focus displacement instrument. The steady film flow that is considered in this study does not have a leading contact line, however, it has two steady side contact lines with the substrate surface at the outer edge of its width. Results reveal that the film width decreases and the average film thickness increases as the film flows down the inclined plane. The film thickness and width decrease but its streamwise velocity increases as surface inclination angle (as measured from the horizontal plane) increases. A higher film flow rate is associated with a higher film thickness, a higher film width, and a higher average film velocity. Films with higher surface tension are associated with a smaller width and a higher average thickness. A ripple develops near the side contact line, i.e., the spanwise distribution of the film thickness exhibits peaks at the outer edges of the film width and the height of this ripple increases as the surface tension or the film flow rate increases. The width of the film decreases at a faster rate along the streamwise direction if liquid film has higher surface tension. Measurements of the film thickness and the film width compare favorably with the numerically simulated results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

A level set method coupled with a volume of fluid method for modeling of gas-liquid interface in bubbly flow / Bogdan A. Nichita in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 15 p. Titre : A level set method coupled with a volume of fluid method for modeling of gas-liquid interface in bubbly flow Type de document : texte imprimé Auteurs : Bogdan A. Nichita, Auteur ; Iztok Zun, Auteur ; John R. Thome, Auteur Année de publication : 2010 Article en page(s) : 15 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : surface  tension;  fluids;  bubbles;  engineering  simulation;  equations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes the implementation of a 3D parallel and Cartesian level set (LS) method coupled with a volume of fluid (VOF) method into the commercial CFD code FLUENT for modeling the gas-liquid interface in bubbly flow. Both level set and volume of fluid methods belong to the so called “one” fluid methods, where a single set of conservation equations is solved and the interface is captured via a scalar function. Since both LS and VOF have advantages and disadvantages, our aim is to couple these two methods to obtain a method, which is superior to both standalone LS and VOF and verify it versus a selection of test cases. VOF is already available in FLUENT , so we implemented an LS method into FLUENT via user defined functions. The level set function is used to compute the surface tension contribution to the momentum equations, via curvature and its normal to the interface, using the Brackbill method while the volume of fluid function is used to capture the interface itself. A re-initialization equation is implemented and solved at every time step using a fifth-order weighted essentially nonoscillatory scheme for the spatial derivative, and a first-order Euler method for time integration. The coupling effect is introduced by solving at the end of each time step an equation, which connects the volume fractions with the level set function. The verification of parasitic currents and interfacial deformation due to numerical error is assessed in comparison to original VOF scheme. Validation is presented for free rising bubbles of different diameters for Morton numbers ranging from 102 to 10−11. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] A level set method coupled with a volume of fluid method for modeling of gas-liquid interface in bubbly flow [texte imprimé] / Bogdan A. Nichita, Auteur ; Iztok Zun, Auteur ; John R. Thome, Auteur . - 2010 . - 15 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 15 p. Mots-clés : surface  tension;  fluids;  bubbles;  engineering  simulation;  equations Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : This paper describes the implementation of a 3D parallel and Cartesian level set (LS) method coupled with a volume of fluid (VOF) method into the commercial CFD code FLUENT for modeling the gas-liquid interface in bubbly flow. Both level set and volume of fluid methods belong to the so called “one” fluid methods, where a single set of conservation equations is solved and the interface is captured via a scalar function. Since both LS and VOF have advantages and disadvantages, our aim is to couple these two methods to obtain a method, which is superior to both standalone LS and VOF and verify it versus a selection of test cases. VOF is already available in FLUENT , so we implemented an LS method into FLUENT via user defined functions. The level set function is used to compute the surface tension contribution to the momentum equations, via curvature and its normal to the interface, using the Brackbill method while the volume of fluid function is used to capture the interface itself. A re-initialization equation is implemented and solved at every time step using a fifth-order weighted essentially nonoscillatory scheme for the spatial derivative, and a first-order Euler method for time integration. The coupling effect is introduced by solving at the end of each time step an equation, which connects the volume fractions with the level set function. The verification of parasitic currents and interfacial deformation due to numerical error is assessed in comparison to original VOF scheme. Validation is presented for free rising bubbles of different diameters for Morton numbers ranging from 102 to 10−11. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

A methodology to measure aerodynamic forces on cylinders in channel flow / Alan A. Thrift in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 09 p. Titre : A methodology to measure aerodynamic forces on cylinders in channel flow Type de document : texte imprimé Auteurs : Alan A. Thrift, Auteur ; Scott J. Brumbaugh, Auteur ; Karen A. Thole, Auteur Année de publication : 2010 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : force;  flow  (dynamics);  aerodynamics;  channels  (hydraulic  engineering);  measurement;  sensors;  drag  (fluid  dynamics);  Reynolds  number;  channel  flow;  cylinders;  force  measurement;  force  sensors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : While the measurement of drag and lift forces on a body in external flow is common practice, the same cannot be said for aerodynamic forces on bodies in internal flows. The inherent difficulty in making force measurements on a body in an internal channel flow is decoupling the body from the bounding walls. The methodology presented in this paper uses a technique to overcome this constraint to accurately measure two components of force on a single cylinder within a single row array, with an aspect ratio (height-to-diameter ratio) of 1. Experiments were conducted with air over a range of Reynolds numbers between 7500 and 35,000 and for three different spanwise pin spacings. Experimental results indicated an increase in cylinder drag with a reduction in spanwise pin spacing. The gas turbine and electronics industries use cylinders or pin fins in internal flow channels to increase heat transfer augmentation through high turbulence and increased surface area. The flow fields in these obstructed channels are difficult to predict, so these measurements can be used to directly compare with predicted drag and lift forces. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] A methodology to measure aerodynamic forces on cylinders in channel flow [texte imprimé] / Alan A. Thrift, Auteur ; Scott J. Brumbaugh, Auteur ; Karen A. Thole, Auteur . - 2010 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 09 p. Mots-clés : force;  flow  (dynamics);  aerodynamics;  channels  (hydraulic  engineering);  measurement;  sensors;  drag  (fluid  dynamics);  Reynolds  number;  channel  flow;  cylinders;  force  measurement;  force  sensors Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : While the measurement of drag and lift forces on a body in external flow is common practice, the same cannot be said for aerodynamic forces on bodies in internal flows. The inherent difficulty in making force measurements on a body in an internal channel flow is decoupling the body from the bounding walls. The methodology presented in this paper uses a technique to overcome this constraint to accurately measure two components of force on a single cylinder within a single row array, with an aspect ratio (height-to-diameter ratio) of 1. Experiments were conducted with air over a range of Reynolds numbers between 7500 and 35,000 and for three different spanwise pin spacings. Experimental results indicated an increase in cylinder drag with a reduction in spanwise pin spacing. The gas turbine and electronics industries use cylinders or pin fins in internal flow channels to increase heat transfer augmentation through high turbulence and increased surface area. The flow fields in these obstructed channels are difficult to predict, so these measurements can be used to directly compare with predicted drag and lift forces. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Far-field boundary condition effects of CFD and free-wake coupling analysis for helicopter rotor / Seong Yong Wie in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 06 p. Titre : Far-field boundary condition effects of CFD and free-wake coupling analysis for helicopter rotor Type de document : texte imprimé Auteurs : Seong Yong Wie, Auteur ; Jae Hoon Lee, Auteur ; Jang Hyuk Kwon, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  wakes;  computational  fluid  dynamics;  rotors;  vortices;  disks;  boundary-value  problems;  inflow;  outflow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Rotor aerodynamics is governed by wake geometry and strength. However, rotor wake characteristics computed by the rotor computational fluid dynamics are not clearly described due to numerical dissipation. To overcome this numerical problem, free-wake is used for wake simulation. The present free-wake describes the inboard vortices as well as the tip vortices of the blade. At each time step, the free-wake provides inflow and outflow conditions of the boundary of the Eulerian domain, and the Euler solver is used for solving the flow field near the rotor blade. Finally, the coupled method is compared with the conventional method and the experimental results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Far-field boundary condition effects of CFD and free-wake coupling analysis for helicopter rotor [texte imprimé] / Seong Yong Wie, Auteur ; Jae Hoon Lee, Auteur ; Jang Hyuk Kwon, Auteur . - 2010 . - 06 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 06 p. Mots-clés : flow  (dynamics);  wakes;  computational  fluid  dynamics;  rotors;  vortices;  disks;  boundary-value  problems;  inflow;  outflow Index. décimale : 620.1 Essais des matériaux. Défauts des matériaux. Protection des matériaux Résumé : Rotor aerodynamics is governed by wake geometry and strength. However, rotor wake characteristics computed by the rotor computational fluid dynamics are not clearly described due to numerical dissipation. To overcome this numerical problem, free-wake is used for wake simulation. The present free-wake describes the inboard vortices as well as the tip vortices of the blade. At each time step, the free-wake provides inflow and outflow conditions of the boundary of the Eulerian domain, and the Euler solver is used for solving the flow field near the rotor blade. Finally, the coupled method is compared with the conventional method and the experimental results. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Microscale falling cylinder viscometer with slip boundary / Khaled M. Bataineh in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 05 p. Titre : Microscale falling cylinder viscometer with slip boundary Type de document : texte imprimé Auteurs : Khaled M. Bataineh, Auteur ; Moh’d A. Al-Nimr, Auteur ; Wafa Batayneh, Auteur Année de publication : 2010 Article en page(s) : 05 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : fluids;  viscosity;  microscale  devices;  boundary-value  problems;  cylinders;  formulas Résumé : This paper theoretically investigates the hydrodynamic behavior of a falling microcylinder viscometer. The Navier slip conditions are applied to all fluid/solid interfacial boundary conditions of the device. Previous investigations focused on the behavior at the macroscale level and did not consider the slip conditions. The slip coefficients for typical devices and operating conditions are found to be major parameters that affect the behavior of the microscale viscometer. Formulas for determining the viscosity coefficients using a microscale viscometer without considering slip conditions give inaccurate results. The theoretical model has been verified by comparing its predictions with that of the macroviscometer after neglecting the slip conditions. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Microscale falling cylinder viscometer with slip boundary [texte imprimé] / Khaled M. Bataineh, Auteur ; Moh’d A. Al-Nimr, Auteur ; Wafa Batayneh, Auteur . - 2010 . - 05 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 05 p. Mots-clés : fluids;  viscosity;  microscale  devices;  boundary-value  problems;  cylinders;  formulas Résumé : This paper theoretically investigates the hydrodynamic behavior of a falling microcylinder viscometer. The Navier slip conditions are applied to all fluid/solid interfacial boundary conditions of the device. Previous investigations focused on the behavior at the macroscale level and did not consider the slip conditions. The slip coefficients for typical devices and operating conditions are found to be major parameters that affect the behavior of the microscale viscometer. Formulas for determining the viscosity coefficients using a microscale viscometer without considering slip conditions give inaccurate results. The theoretical model has been verified by comparing its predictions with that of the macroviscometer after neglecting the slip conditions. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Shear flow over a wavy surface with partial slip / Wang, C. Y. in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 03 p. Titre : Shear flow over a wavy surface with partial slip Type de document : texte imprimé Auteurs : Wang, C. Y., Auteur Année de publication : 2010 Article en page(s) : 03 p. Note générale : fluids engineering Langues : Anglais (eng) Résumé : A viscous shear flow moves parallel to a wavy plate. Partial slip occurs on the wavy surface. The problem is solved by perturbation about a small amplitude parameter, namely, the amplitude to wavelength ratio. It is found that the interaction of waviness and slip decreases the apparent slip coefficient. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Shear flow over a wavy surface with partial slip [texte imprimé] / Wang, C. Y., Auteur . - 2010 . - 03 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 03 p. Résumé : A viscous shear flow moves parallel to a wavy plate. Partial slip occurs on the wavy surface. The problem is solved by perturbation about a small amplitude parameter, namely, the amplitude to wavelength ratio. It is found that the interaction of waviness and slip decreases the apparent slip coefficient. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Drag reduction of tractor-trailers using optimized add-on devices / Fu-Hung Hsu in Transactions of the ASME . Journal of fluids engineering, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 06 p. Titre : Drag reduction of tractor-trailers using optimized add-on devices Type de document : texte imprimé Auteurs : Fu-Hung Hsu, Auteur ; Roger L. Davis, Auteur Année de publication : 2010 Article en page(s) : 06 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  turbulence;  drag  (fluid  dynamics);  design;  engineering  simulation;  vehicles;  drag  reduction;  boats;  fuel  consumption Résumé : Tractor-trailers have a higher drag coefficient than other vehicles due to their bluff-body shape. Numerous add-on devices have been invented to help reduce drag and fuel consumption. The current research extends our previous idea of add-on humps and investigates their effect in conjunction with curved boat-tail flaps. Computational fluid dynamics in the form of unsteady Reynolds-averaged Navier–Stokes and detached-eddy simulations were used to determine viable design strategies. A 3D baseline computational model was constructed using an Ahmed body. Design optimization was applied on the new add-on devices. The results from the optimized design were shown to have a 50.9% reduction in drag coefficient. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Drag reduction of tractor-trailers using optimized add-on devices [texte imprimé] / Fu-Hung Hsu, Auteur ; Roger L. Davis, Auteur . - 2010 . - 06 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 132 N° 8 (Août 2010) . - 06 p. Mots-clés : flow  (dynamics);  turbulence;  drag  (fluid  dynamics);  design;  engineering  simulation;  vehicles;  drag  reduction;  boats;  fuel  consumption Résumé : Tractor-trailers have a higher drag coefficient than other vehicles due to their bluff-body shape. Numerous add-on devices have been invented to help reduce drag and fuel consumption. The current research extends our previous idea of add-on humps and investigates their effect in conjunction with curved boat-tail flaps. Computational fluid dynamics in the form of unsteady Reynolds-averaged Navier–Stokes and detached-eddy simulations were used to determine viable design strategies. A 3D baseline computational model was constructed using an Ahmed body. Design optimization was applied on the new add-on devices. The results from the optimized design were shown to have a 50.9% reduction in drag coefficient. DEWEY : 620.1 ISSN : 0098-2202 En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

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