Dépouillements

Swimming and flying in nature / Promode R. Bandyopadhyay in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 29 p. Titre : Swimming and flying in nature : the Route Toward Applications: the Freeman scholar lecture Type de document : texte imprimé Auteurs : Promode R. Bandyopadhyay, Auteur Année de publication : 2009 Article en page(s) : 29 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : kinematics;  force;  flow  (dynamics);  measurement;  motion;  drag  (fluid  dynamics);  thrust;  propulsion;  wakes;  modeling;  vehicles;  vortices;  fins;  wings;  flight;  mechanisms Résumé : Evolution is a slow but sure process of perfecting design to give a life-form a natural advantage in a competitive environment. The resulting complexity and performance are so sophisticated that, by and large, they are yet to be matched by man-made devices. They offer a vast array of design inspirations. The lessons from swimming and flying animals that are useful to fluids engineering devices are considered. The science and engineering of this subject—termed “biorobotics” here—are reviewed. The subject, being of dynamic objects, spans fluid dynamics, materials, and control, as well as their integration. The emphasis is on understanding the underlying science and design principles and applying them to transition to human usefulness rather than to conduct any biomimicry. First, the gaps between nature and man-made devices in terms of fluids engineering characteristics are quantitatively defined. To bridge these gaps, we then identify the underlying science principles in the production of unsteady high-lift that nature is boldly using, but that engineers have preferred to refrain from or have not conceived of. This review is primarily concerned with the leading-edge vortex phenomenon that is mainly responsible for unsteady high-lift. Next, design laws are determined. Several applications are discussed and the status of the closure of the gaps between nature and engineering is reviewed. Finally, recommendations for future research in unsteady fluids engineering are given. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Swimming and flying in nature : the Route Toward Applications: the Freeman scholar lecture [texte imprimé] / Promode R. Bandyopadhyay, Auteur . - 2009 . - 29 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 29 p. Mots-clés : kinematics;  force;  flow  (dynamics);  measurement;  motion;  drag  (fluid  dynamics);  thrust;  propulsion;  wakes;  modeling;  vehicles;  vortices;  fins;  wings;  flight;  mechanisms Résumé : Evolution is a slow but sure process of perfecting design to give a life-form a natural advantage in a competitive environment. The resulting complexity and performance are so sophisticated that, by and large, they are yet to be matched by man-made devices. They offer a vast array of design inspirations. The lessons from swimming and flying animals that are useful to fluids engineering devices are considered. The science and engineering of this subject—termed “biorobotics” here—are reviewed. The subject, being of dynamic objects, spans fluid dynamics, materials, and control, as well as their integration. The emphasis is on understanding the underlying science and design principles and applying them to transition to human usefulness rather than to conduct any biomimicry. First, the gaps between nature and man-made devices in terms of fluids engineering characteristics are quantitatively defined. To bridge these gaps, we then identify the underlying science principles in the production of unsteady high-lift that nature is boldly using, but that engineers have preferred to refrain from or have not conceived of. This review is primarily concerned with the leading-edge vortex phenomenon that is mainly responsible for unsteady high-lift. Next, design laws are determined. Several applications are discussed and the status of the closure of the gaps between nature and engineering is reviewed. Finally, recommendations for future research in unsteady fluids engineering are given. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Transient simulation of the aerodynamic response of a double-deck bus in gusty winds / Hassan Hemida in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 10 p. Titre : Transient simulation of the aerodynamic response of a double-deck bus in gusty winds Type de document : texte imprimé Auteurs : Hassan Hemida, Auteur ; Siniša Krajnovic, Auteur Année de publication : 2009 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : double  deck  bus;  aerodynamic  response;  Reynolds  number Résumé : The purpose of the research reported in this paper was to investigate the aerodynamic response of a double-deck bus in gusty winds using a detached-eddy simulation (DES). The bus was subjected to three different scenarios of wind gusts: gust in a wind tunnel, gust in a natural wind, and gust behind the exit of a tunnel. The proposed scenarios of gusts are in the time domain and take into account the dynamic behavior of natural winds. The Reynolds number of the flow, based on the time-averaged speed of the side wind and a reference length of 0.1 m, was 1.3×106. Detailed transient responses of the aerodynamic coefficients and flow structures were investigated. Good agreement was found between the DES results and the available experimental data. A comparison between the influence of the different gust scenarios on the aerodynamic coefficients shows that the gust behind the exit from a tunnel has a stronger influence on the aerodynamics than the other gust scenarios. Moreover, the influence of the gusts on the time history of aerodynamic coefficients is found to be limited to the period of the gust. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Transient simulation of the aerodynamic response of a double-deck bus in gusty winds [texte imprimé] / Hassan Hemida, Auteur ; Siniša Krajnovic, Auteur . - 2009 . - 10 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 10 p. Mots-clés : double  deck  bus;  aerodynamic  response;  Reynolds  number Résumé : The purpose of the research reported in this paper was to investigate the aerodynamic response of a double-deck bus in gusty winds using a detached-eddy simulation (DES). The bus was subjected to three different scenarios of wind gusts: gust in a wind tunnel, gust in a natural wind, and gust behind the exit of a tunnel. The proposed scenarios of gusts are in the time domain and take into account the dynamic behavior of natural winds. The Reynolds number of the flow, based on the time-averaged speed of the side wind and a reference length of 0.1 m, was 1.3×106. Detailed transient responses of the aerodynamic coefficients and flow structures were investigated. Good agreement was found between the DES results and the available experimental data. A comparison between the influence of the different gust scenarios on the aerodynamic coefficients shows that the gust behind the exit from a tunnel has a stronger influence on the aerodynamics than the other gust scenarios. Moreover, the influence of the gusts on the time history of aerodynamic coefficients is found to be limited to the period of the gust. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Assessment measures for engineering LES applications / I. Celik in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 10 p. Titre : Assessment measures for engineering LES applications Type de document : texte imprimé Auteurs : I. Celik, Auteur ; M. Klein, Auteur ; J. Janicka, Auteur Année de publication : 2009 Article en page(s) : 10 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : large  eddy  simulation;  turbulent  scale Résumé : Anticipating that large eddy simulations will increasingly become the future engineering tool for research, development, and design, it is deemed necessary to formulate some quality assessment measures that can be used to judge the resolution of turbulent scales and the accuracy of predictions. In this context some new and refined measures are proposed and compared with those already published by the authors in the common literature. These measures involve (a) fraction of the total turbulent kinetic energy, (b) relative grid size with respect to Kolmogorov or Taylor scales, and (c) relative effective subgrid/numerical viscosity with respect to molecular viscosity. In addition, an attempt is made to segregate the contributions from numerical and modeling errors. Proposed measures are applied to various test cases and validated against fully resolved large eddy simulation and/or direct numerical simulation whenever possible. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Assessment measures for engineering LES applications [texte imprimé] / I. Celik, Auteur ; M. Klein, Auteur ; J. Janicka, Auteur . - 2009 . - 10 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 10 p. Mots-clés : large  eddy  simulation;  turbulent  scale Résumé : Anticipating that large eddy simulations will increasingly become the future engineering tool for research, development, and design, it is deemed necessary to formulate some quality assessment measures that can be used to judge the resolution of turbulent scales and the accuracy of predictions. In this context some new and refined measures are proposed and compared with those already published by the authors in the common literature. These measures involve (a) fraction of the total turbulent kinetic energy, (b) relative grid size with respect to Kolmogorov or Taylor scales, and (c) relative effective subgrid/numerical viscosity with respect to molecular viscosity. In addition, an attempt is made to segregate the contributions from numerical and modeling errors. Proposed measures are applied to various test cases and validated against fully resolved large eddy simulation and/or direct numerical simulation whenever possible. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Slip-flow pressure drop in microchannels of general cross section / M. Bahrami in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 08 p. Titre : Slip-flow pressure drop in microchannels of general cross section Type de document : texte imprimé Auteurs : M. Bahrami, Auteur ; A. Tamayol, Auteur ; P. Taheri, Auteur Année de publication : 2009 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : compact  analytical  model;  pressure  drop Résumé : In the present study, a compact analytical model is developed to determine the pressure drop of fully-developed, incompressible, and constant properties slip-flow through arbitrary cross section microchannels. An averaged first-order Maxwell slip boundary condition is considered. Introducing a relative velocity, the difference between the bulk flow and the boundary velocities, the axial momentum reduces to Poisson’s equation with homogeneous boundary condition. Square root of area is selected as the characteristic length scale. The model of (2006, “ Pressure Drop of Laminar, Fully Developed Flow in Microchannels of Arbitrary Cross Section,” ASME J. Fluids Eng., 128, pp. 1036–1044), which was developed for no-slip boundary condition, is extended to cover the slip-flow regime in this study. The proposed model for pressure drop is a function of geometrical parameters of the channel: cross sectional area, perimeter, polar moment of inertia, and the Knudsen number. The model is successfully validated against existing numerical and experimental data collected from different sources in literature for several shapes, including circular, rectangular, trapezoidal, and double-trapezoidal cross sections and a variety of gases such as nitrogen, argon, and helium. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Slip-flow pressure drop in microchannels of general cross section [texte imprimé] / M. Bahrami, Auteur ; A. Tamayol, Auteur ; P. Taheri, Auteur . - 2009 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 08 p. Mots-clés : compact  analytical  model;  pressure  drop Résumé : In the present study, a compact analytical model is developed to determine the pressure drop of fully-developed, incompressible, and constant properties slip-flow through arbitrary cross section microchannels. An averaged first-order Maxwell slip boundary condition is considered. Introducing a relative velocity, the difference between the bulk flow and the boundary velocities, the axial momentum reduces to Poisson’s equation with homogeneous boundary condition. Square root of area is selected as the characteristic length scale. The model of (2006, “ Pressure Drop of Laminar, Fully Developed Flow in Microchannels of Arbitrary Cross Section,” ASME J. Fluids Eng., 128, pp. 1036–1044), which was developed for no-slip boundary condition, is extended to cover the slip-flow regime in this study. The proposed model for pressure drop is a function of geometrical parameters of the channel: cross sectional area, perimeter, polar moment of inertia, and the Knudsen number. The model is successfully validated against existing numerical and experimental data collected from different sources in literature for several shapes, including circular, rectangular, trapezoidal, and double-trapezoidal cross sections and a variety of gases such as nitrogen, argon, and helium. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Long-wave instabilities in a non-newtonian film on a nonuniformly heated inclined plane / I. Mohammed Rizwan Sadiq in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 17 p. Titre : Long-wave instabilities in a non-newtonian film on a nonuniformly heated inclined plane Type de document : texte imprimé Auteurs : I. Mohammed Rizwan Sadiq, Auteur ; R. Usha, Auteur Année de publication : 2009 Article en page(s) : 17 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : non-Newtonian  film;  thermocapillary  instability;  surface-wave  instabilities Résumé : A thin liquid layer of a non-Newtonian film falling down an inclined plane that is subjected to nonuniform heating has been considered. The temperature of the inclined plane is assumed to be linearly distributed and the case when the temperature gradient is positive or negative is investigated. The film flow is influenced by gravity, mean surface tension, and thermocapillary forces acting along the free surface. The coupling of thermocapillary instability and surface-wave instabilities is studied for two-dimensional disturbances. A nonlinear evolution equation is derived by applying the long-wave theory, and the equation governs the evolution of a power-law film flowing down a nonuniformly heated inclined plane. The linear stability analysis shows that the film flow system is stable when the plate temperature decreases in the downstream direction while it is less stable for increasing temperature along the plate. Weakly nonlinear stability analysis using the method of multiple scales has been investigated and this leads to a secular equation of the Ginzburg–Landau type. The analysis shows that both supercritical stability and subcritical instability are possible for the film flow system. The results indicate the existence of finite-amplitude waves, and the threshold amplitude and nonlinear speed of these waves are influenced by thermocapillarity. The nonlinear evolution equation for the film thickness is solved numerically in a periodic domain in the supercritical stable region, and the results show that the shape of the wave is influenced by the choice of wave number, non-Newtonian rheology, and nonuniform heating. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Long-wave instabilities in a non-newtonian film on a nonuniformly heated inclined plane [texte imprimé] / I. Mohammed Rizwan Sadiq, Auteur ; R. Usha, Auteur . - 2009 . - 17 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 17 p. Mots-clés : non-Newtonian  film;  thermocapillary  instability;  surface-wave  instabilities Résumé : A thin liquid layer of a non-Newtonian film falling down an inclined plane that is subjected to nonuniform heating has been considered. The temperature of the inclined plane is assumed to be linearly distributed and the case when the temperature gradient is positive or negative is investigated. The film flow is influenced by gravity, mean surface tension, and thermocapillary forces acting along the free surface. The coupling of thermocapillary instability and surface-wave instabilities is studied for two-dimensional disturbances. A nonlinear evolution equation is derived by applying the long-wave theory, and the equation governs the evolution of a power-law film flowing down a nonuniformly heated inclined plane. The linear stability analysis shows that the film flow system is stable when the plate temperature decreases in the downstream direction while it is less stable for increasing temperature along the plate. Weakly nonlinear stability analysis using the method of multiple scales has been investigated and this leads to a secular equation of the Ginzburg–Landau type. The analysis shows that both supercritical stability and subcritical instability are possible for the film flow system. The results indicate the existence of finite-amplitude waves, and the threshold amplitude and nonlinear speed of these waves are influenced by thermocapillarity. The nonlinear evolution equation for the film thickness is solved numerically in a periodic domain in the supercritical stable region, and the results show that the shape of the wave is influenced by the choice of wave number, non-Newtonian rheology, and nonuniform heating. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Effect of geometrical parameters on vortex-induced vibration of a splitter plate / T. Pärssinen in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 09 p. Titre : Effect of geometrical parameters on vortex-induced vibration of a splitter plate Type de document : texte imprimé Auteurs : T. Pärssinen, Auteur ; H. Eloranta, Auteur ; P. Saarenrinne, Auteur Année de publication : 2009 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : vortex-induced  vibration;  splitter  plate;  geometrical  parameters Résumé : An experimental study on the effects of various geometrical parameters to the characteristics of vortex-induced vibration (VIV) of a splitter plate is presented. The dynamic response of the fluid-structure system was measured using particle image velocimetry and laser telemetry simultaneously. Combined data of these techniques allow the assessment of the variation in the VIV response due to geometrical parameters, such as channel geometry, aspect ratio (AR), and trailing-edge thickness (d) as well as the imprint of the excited vibration mode on the flow. The effects of AR and d were both investigated with three different plate geometries and the effect of channel convergence was studied with a single plate geometry. Measurements were performed over a range of Reynolds numbers (Re). The results show that the vibrational response of the combined fluid-structure system is affected by the VIV instability in all cases. Within the measured Re range, a characteristic stepwise behavior of the frequency of the dominant vibration mode is observed. This behavior is explained by the synchronization between the vortex shedding frequency (f0) and a natural frequency (fN) of the fluid-structure system. The results further indicate that this response is modified by geometrical parameters. Channel convergence, i.e., flow acceleration, enhances the vortex shedding, which, in turn, increases the excitation level leading to stronger VIV. Channel convergence does not have a significant effect on f0 or on the dimensionless vibration amplitude (A∕d). An increase of both the number of excited fN’s and the level of synchronization was observed with the lowest AR case. The results also suggest that d is the dominant geometrical parameter. It reduces both the A∕d of the plate and the number of synchronization regions. This stronger effect on the response of the VIV system is due to the direct effect of d on the excitation mechanism. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Effect of geometrical parameters on vortex-induced vibration of a splitter plate [texte imprimé] / T. Pärssinen, Auteur ; H. Eloranta, Auteur ; P. Saarenrinne, Auteur . - 2009 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 09 p. Mots-clés : vortex-induced  vibration;  splitter  plate;  geometrical  parameters Résumé : An experimental study on the effects of various geometrical parameters to the characteristics of vortex-induced vibration (VIV) of a splitter plate is presented. The dynamic response of the fluid-structure system was measured using particle image velocimetry and laser telemetry simultaneously. Combined data of these techniques allow the assessment of the variation in the VIV response due to geometrical parameters, such as channel geometry, aspect ratio (AR), and trailing-edge thickness (d) as well as the imprint of the excited vibration mode on the flow. The effects of AR and d were both investigated with three different plate geometries and the effect of channel convergence was studied with a single plate geometry. Measurements were performed over a range of Reynolds numbers (Re). The results show that the vibrational response of the combined fluid-structure system is affected by the VIV instability in all cases. Within the measured Re range, a characteristic stepwise behavior of the frequency of the dominant vibration mode is observed. This behavior is explained by the synchronization between the vortex shedding frequency (f0) and a natural frequency (fN) of the fluid-structure system. The results further indicate that this response is modified by geometrical parameters. Channel convergence, i.e., flow acceleration, enhances the vortex shedding, which, in turn, increases the excitation level leading to stronger VIV. Channel convergence does not have a significant effect on f0 or on the dimensionless vibration amplitude (A∕d). An increase of both the number of excited fN’s and the level of synchronization was observed with the lowest AR case. The results also suggest that d is the dominant geometrical parameter. It reduces both the A∕d of the plate and the number of synchronization regions. This stronger effect on the response of the VIV system is due to the direct effect of d on the excitation mechanism. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Modeling of cavitation bubble dynamics in multicomponent mixtures / Si Huang in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 05 p. Titre : Modeling of cavitation bubble dynamics in multicomponent mixtures Type de document : texte imprimé Auteurs : Si Huang, Auteur ; A. A. Mohamad, Auteur Année de publication : 2009 Article en page(s) : 05 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : multicomponent  mixtures;  first-order  bubble-wall  Mach  number Résumé : Investigation on cavitation in multicomponent (solid-liquid and liquid-liquid) mixtures has many applications in the industries and engineering. In this paper, for simulation of multicomponent mixtures, a set of equations with first-order bubble-wall Mach number is derived for a single spherical bubble in quasihomogeneous mixtures. Cavitation bubble behaviors in several kinds of liquid-liquid and solid-liquid mixtures are numerically calculated based on the current model, including the temporal variations in the bubble radius, pressure, and temperature inside the bubble. Specifically, the analysis is focused on the impact of pressure and temperature, while the bubble collapses in the mixtures. The computed results are compared with the previously reported experimental ones to demonstrate the validity of the current model and the numerical procedures. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Modeling of cavitation bubble dynamics in multicomponent mixtures [texte imprimé] / Si Huang, Auteur ; A. A. Mohamad, Auteur . - 2009 . - 05 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 05 p. Mots-clés : multicomponent  mixtures;  first-order  bubble-wall  Mach  number Résumé : Investigation on cavitation in multicomponent (solid-liquid and liquid-liquid) mixtures has many applications in the industries and engineering. In this paper, for simulation of multicomponent mixtures, a set of equations with first-order bubble-wall Mach number is derived for a single spherical bubble in quasihomogeneous mixtures. Cavitation bubble behaviors in several kinds of liquid-liquid and solid-liquid mixtures are numerically calculated based on the current model, including the temporal variations in the bubble radius, pressure, and temperature inside the bubble. Specifically, the analysis is focused on the impact of pressure and temperature, while the bubble collapses in the mixtures. The computed results are compared with the previously reported experimental ones to demonstrate the validity of the current model and the numerical procedures. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Parameters for assessing oil reservoir water flooding additives / Nico Reuvers in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 06 p. Titre : Parameters for assessing oil reservoir water flooding additives Type de document : texte imprimé Auteurs : Nico Reuvers, Auteur ; Michael Golombok, Auteur Année de publication : 2009 Article en page(s) : 06 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : fluid  additives;  water  flooding;  oil  reservoir Résumé : This paper is concerned with deriving parameters for assessing the effectiveness of fluid additives to improve water flooding during enhanced oil recovery. We focus particularly on the use of rheological modifiers, which do not show monotonic behavior with the shear rate within the rock pores. We derive figures of merit based on (1) relative retardation in high and low permeability rock, (2) profile flattening, and (3) injectivity index. Only the last of these provides a measure of water flood profile improvement while maintaining sufficient fluid flow and production levels. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Parameters for assessing oil reservoir water flooding additives [texte imprimé] / Nico Reuvers, Auteur ; Michael Golombok, Auteur . - 2009 . - 06 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 06 p. Mots-clés : fluid  additives;  water  flooding;  oil  reservoir Résumé : This paper is concerned with deriving parameters for assessing the effectiveness of fluid additives to improve water flooding during enhanced oil recovery. We focus particularly on the use of rheological modifiers, which do not show monotonic behavior with the shear rate within the rock pores. We derive figures of merit based on (1) relative retardation in high and low permeability rock, (2) profile flattening, and (3) injectivity index. Only the last of these provides a measure of water flood profile improvement while maintaining sufficient fluid flow and production levels. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Improvements of particle near-wall velocity and erosion predictions using a commercial CFD code / Yongli Zhang in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 09 p. Titre : Improvements of particle near-wall velocity and erosion predictions using a commercial CFD code Type de document : texte imprimé Auteurs : Yongli Zhang, Auteur ; Brenton S. McLaury, Auteur ; Siamack A. Shirazi, Auteur Année de publication : 2009 Article en page(s) : 09 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : CFD  codes;  pipe  walls;  velocity;  near-wall  modifications Résumé : The determination of a representative particle impacting velocity is an important component in calculating solid particle erosion inside pipe geometry. Currently, most commercial computational fluid dynamics (CFD) codes allow the user to calculate particle trajectories using a Lagrangian approach. Additionally, the CFD codes calculate particle impact velocities with the pipe walls. However, these commercial CFD codes normally use a wall function to simulate the turbulent velocity field in the near-wall region. This wall-function velocity field near the wall can affect the small particle motion in the near-wall region. Furthermore, the CFD codes assume that particles have zero volume when particle impact information is being calculated. In this investigation, particle motions that are simulated using a commercially available CFD code are examined in the near-wall region. Calculated solid particle erosion patterns are compared with experimental data to investigate the accuracy of the models that are being used to calculate particle impacting velocities. While not considered in particle tracking routines in most CFD codes, the turbulent velocity profile in the near-wall region is taken into account in this investigation, and the effect on particle impact velocity is investigated. The simulation results show that the particle impact velocity is affected significantly when near-wall velocity profile is implemented. In addition, the effects of particle size are investigated in the near-wall region of a turbulent flow in a 90 deg sharp bend. A CFD code is modified to account for particle size effects in the near-wall region before and after the particle impact. It is found from the simulations that accounting for the rebound at the particle radius helps avoid nonphysical impacts and reduces the number of impacts by more than one order-of-magnitude for small particles (25 μm) due to turbulent velocity fluctuations. For large particles (256 μm), however, nonphysical impacts are not observed in the simulations. Solid particle erosion is predicted before and after introducing these modifications, and the results are compared with experimental data. It is shown that the near-wall modification and turbulent particle interactions significantly affect the simulation results. Modifications can significantly improve the current CFD-based solid particle erosion modeling. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Improvements of particle near-wall velocity and erosion predictions using a commercial CFD code [texte imprimé] / Yongli Zhang, Auteur ; Brenton S. McLaury, Auteur ; Siamack A. Shirazi, Auteur . - 2009 . - 09 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 09 p. Mots-clés : CFD  codes;  pipe  walls;  velocity;  near-wall  modifications Résumé : The determination of a representative particle impacting velocity is an important component in calculating solid particle erosion inside pipe geometry. Currently, most commercial computational fluid dynamics (CFD) codes allow the user to calculate particle trajectories using a Lagrangian approach. Additionally, the CFD codes calculate particle impact velocities with the pipe walls. However, these commercial CFD codes normally use a wall function to simulate the turbulent velocity field in the near-wall region. This wall-function velocity field near the wall can affect the small particle motion in the near-wall region. Furthermore, the CFD codes assume that particles have zero volume when particle impact information is being calculated. In this investigation, particle motions that are simulated using a commercially available CFD code are examined in the near-wall region. Calculated solid particle erosion patterns are compared with experimental data to investigate the accuracy of the models that are being used to calculate particle impacting velocities. While not considered in particle tracking routines in most CFD codes, the turbulent velocity profile in the near-wall region is taken into account in this investigation, and the effect on particle impact velocity is investigated. The simulation results show that the particle impact velocity is affected significantly when near-wall velocity profile is implemented. In addition, the effects of particle size are investigated in the near-wall region of a turbulent flow in a 90 deg sharp bend. A CFD code is modified to account for particle size effects in the near-wall region before and after the particle impact. It is found from the simulations that accounting for the rebound at the particle radius helps avoid nonphysical impacts and reduces the number of impacts by more than one order-of-magnitude for small particles (25 μm) due to turbulent velocity fluctuations. For large particles (256 μm), however, nonphysical impacts are not observed in the simulations. Solid particle erosion is predicted before and after introducing these modifications, and the results are compared with experimental data. It is shown that the near-wall modification and turbulent particle interactions significantly affect the simulation results. Modifications can significantly improve the current CFD-based solid particle erosion modeling. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Modeling the onset of gas entrainment in a single downward discharge from a stratified gas-liquid region with liquid crossflow / R. C. Bowden in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 08 p. Titre : Modeling the onset of gas entrainment in a single downward discharge from a stratified gas-liquid region with liquid crossflow Type de document : texte imprimé Auteurs : R. C. Bowden, Auteur ; I. G. Hassan, Auteur Année de publication : 2009 Article en page(s) : 08 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  equations Résumé : The critical height at the onset of gas entrainment, in a single downward oriented discharge from a stratified gas-liquid region with liquid crossflow, was modeled. The assumptions made in the development of the model reduced the problem to that of a potential flow. The discharge was modeled as a point-sink while the crossflow was said to be uniform at the main pipe inlet. The potential function was determined from a superposition of known solutions for a point-sink and uniform flow. The resulting system of three equations demonstrated that the flow field was dominated by the discharge and crossflow Froude numbers. The system was solved numerically and provided a relationship between the geometry, flow conditions, dip location, and critical height. The model predicted that the critical height increased with the discharge Froude number and decreased with the crossflow Froude number. With no imposed crossflow, the model prediction demonstrated agreement with transient and quasisteady experimental data to within ±30%. Existing experimental correlations showed inconsistent crossflow effects on the critical height and disagreed with the model predictions at high discharge Froude numbers. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Modeling the onset of gas entrainment in a single downward discharge from a stratified gas-liquid region with liquid crossflow [texte imprimé] / R. C. Bowden, Auteur ; I. G. Hassan, Auteur . - 2009 . - 08 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 08 p. Mots-clés : flow  (dynamics);  equations Résumé : The critical height at the onset of gas entrainment, in a single downward oriented discharge from a stratified gas-liquid region with liquid crossflow, was modeled. The assumptions made in the development of the model reduced the problem to that of a potential flow. The discharge was modeled as a point-sink while the crossflow was said to be uniform at the main pipe inlet. The potential function was determined from a superposition of known solutions for a point-sink and uniform flow. The resulting system of three equations demonstrated that the flow field was dominated by the discharge and crossflow Froude numbers. The system was solved numerically and provided a relationship between the geometry, flow conditions, dip location, and critical height. The model predicted that the critical height increased with the discharge Froude number and decreased with the crossflow Froude number. With no imposed crossflow, the model prediction demonstrated agreement with transient and quasisteady experimental data to within ±30%. Existing experimental correlations showed inconsistent crossflow effects on the critical height and disagreed with the model predictions at high discharge Froude numbers. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Hot-wire anemometry for velocity measurements in nanopowder flows / Sergey P. Bardakhanov in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 04 p. Titre : Hot-wire anemometry for velocity measurements in nanopowder flows Type de document : texte imprimé Auteurs : Sergey P. Bardakhanov, Auteur ; Sang W. Joo, Auteur Année de publication : 2009 Article en page(s) : 04 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : velocity-field  measurements;  hot-wire  anemometry Résumé : A new technique for velocity-field measurements in fine granular systems is introduced. The hot-wire anemometry, mainly used for gaseous flows, is applied to nanopowders and is found to be a viable experimental method for flow measurements. A generic chute flow of aluminum oxide C and Aerosil A-90 and A-380 powders through a vertical channel is chosen as a test platform, and the results suggest that the hot-wire anemometry is a favorable option for nanopowder measurements. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Hot-wire anemometry for velocity measurements in nanopowder flows [texte imprimé] / Sergey P. Bardakhanov, Auteur ; Sang W. Joo, Auteur . - 2009 . - 04 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 04 p. Mots-clés : velocity-field  measurements;  hot-wire  anemometry Résumé : A new technique for velocity-field measurements in fine granular systems is introduced. The hot-wire anemometry, mainly used for gaseous flows, is applied to nanopowders and is found to be a viable experimental method for flow measurements. A generic chute flow of aluminum oxide C and Aerosil A-90 and A-380 powders through a vertical channel is chosen as a test platform, and the results suggest that the hot-wire anemometry is a favorable option for nanopowder measurements. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Effects of jet obliquity on hydraulic jumps formed by impinging circular liquid jets on a moving horizontal plate / R. P. Kate in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 05 p. Titre : Effects of jet obliquity on hydraulic jumps formed by impinging circular liquid jets on a moving horizontal plate Type de document : texte imprimé Auteurs : R. P. Kate, Auteur ; P. K. Das, Auteur ; Suman Chakraborty, Auteur Année de publication : 2009 Article en page(s) : 05 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : spatial  patterns  formed;  jet  obliquity;  hydraulic  jumps Résumé : The present work attempts to investigate the effects of jet obliquity on the spatial patterns formed as a consequence of hydraulic jumps due to the impingement of circular liquid jets on continuously moving but nonaccelerating horizontal flat plates. Both the normal and the oblique impinging jets are considered, in order to characterize the contrasting features of the associated hydraulic jump mechanisms. Theoretical calculations are executed to obtain the locations of the jump, for different jet and plate velocities and jet inclination angles, using a depth-averaged momentum integral equation for shallow-free surface flows. Comparisons are subsequently made between the theoretical predictions and experimental observations reported in the literature, and a good agreement between these two can be observed. Special cases of a circular hydraulic jump when the target plate is stationary and the impinging jet is vertical, and elliptic hydraulic jumps when the target plate is stationary and the impinging jet is obliquely inclined, are also discussed. It is conjectured that flow due to impinging jets on a horizontal moving plate can be modeled as an equivalent flow due to an inclined impinging jet on stationary horizontal flat plates, with appropriate alterations in the jet velocity and the jet inclination angles. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Effects of jet obliquity on hydraulic jumps formed by impinging circular liquid jets on a moving horizontal plate [texte imprimé] / R. P. Kate, Auteur ; P. K. Das, Auteur ; Suman Chakraborty, Auteur . - 2009 . - 05 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 05 p. Mots-clés : spatial  patterns  formed;  jet  obliquity;  hydraulic  jumps Résumé : The present work attempts to investigate the effects of jet obliquity on the spatial patterns formed as a consequence of hydraulic jumps due to the impingement of circular liquid jets on continuously moving but nonaccelerating horizontal flat plates. Both the normal and the oblique impinging jets are considered, in order to characterize the contrasting features of the associated hydraulic jump mechanisms. Theoretical calculations are executed to obtain the locations of the jump, for different jet and plate velocities and jet inclination angles, using a depth-averaged momentum integral equation for shallow-free surface flows. Comparisons are subsequently made between the theoretical predictions and experimental observations reported in the literature, and a good agreement between these two can be observed. Special cases of a circular hydraulic jump when the target plate is stationary and the impinging jet is vertical, and elliptic hydraulic jumps when the target plate is stationary and the impinging jet is obliquely inclined, are also discussed. It is conjectured that flow due to impinging jets on a horizontal moving plate can be modeled as an equivalent flow due to an inclined impinging jet on stationary horizontal flat plates, with appropriate alterations in the jet velocity and the jet inclination angles. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Validation / Patrick J. Roache in Transactions of the ASME . Journal of fluids engineering, Vol. 131 N° 3 (Mars 2009) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 04 p. Titre : Validation : what does it mean? Type de document : texte imprimé Auteurs : Patrick J. Roache, Auteur Année de publication : 2009 Article en page(s) : 04 p. Note générale : fluids engineering Langues : Anglais (eng) Mots-clés : flow  (dynamics);  turbulence;  engineers;  accreditation;  computational  fluid  dynamics;  design;  modeling;  calibration;  model  validation;  regulations;  Reynolds-averaged  Navier–Stokes  equations Résumé : Ambiguities, inconsistencies, and recommended interpretations of the commonly cited definition of validation for computational fluid dynamics codes/models are examined. It is shown that the definition-deduction approach is prone to misinterpretation, and that bottom-up descriptions rather than top-down legalistic definitions are to be preferred for science-based engineering and journal policies, though legalistic definitions are necessary for contracts. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Validation : what does it mean? [texte imprimé] / Patrick J. Roache, Auteur . - 2009 . - 04 p. fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 131 N° 3 (Mars 2009) . - 04 p. Mots-clés : flow  (dynamics);  turbulence;  engineers;  accreditation;  computational  fluid  dynamics;  design;  modeling;  calibration;  model  validation;  regulations;  Reynolds-averaged  Navier–Stokes  equations Résumé : Ambiguities, inconsistencies, and recommended interpretations of the commonly cited definition of validation for computational fluid dynamics codes/models are examined. It is shown that the definition-deduction approach is prone to misinterpretation, and that bottom-up descriptions rather than top-down legalistic definitions are to be preferred for science-based engineering and journal policies, though legalistic definitions are necessary for contracts. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

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