Documents disponibles écrits par cet auteur

Fluid flow in an annular microchannel subjected to uniform wall injections / Mohammad Layeghi in Transactions of the ASME . Journal of fluids engineering, Vol. 130 N° 5 (Mai 2008) 

Public ISBD [article]  in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 5 (Mai 2008) . - 5 p. Titre : Fluid flow in an annular microchannel subjected to uniform wall injections Type de document : texte imprimé Auteurs : Mohammad Layeghi, Auteur ; Hamid Reza Seyf, Auteur Année de publication : 2009 Article en page(s) : 5 p. Note générale : Fluids engineering Langues : Anglais (eng) Mots-clés : Fluid  dynamics;  Reynolds  number;  equations;  microchannels;  Navier-Stokes  equations;  pressure;  differential  equations Résumé : Analytical analysis of fluid flow in an annular microchannel subjected to uniform wall injection at various Reynolds numbers is presented. The classical Navier–Stokes equations are used in the present study. Mathematically, using an appropriate change of variable, Navier–Stokes equations are transformed to a set of nonlinear ordinary differential equations. The governing equations are analytically solved using series solution method. Some analytical results are given for the prediction of velocity profiles and pressure distributions in annular microchannels. The agreement between the computational fluid dynamics and the analytical predictions is very good. However, the analytical results are valid in a limited range of radius ratios and needs more study. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...] [article] Fluid flow in an annular microchannel subjected to uniform wall injections [texte imprimé] / Mohammad Layeghi, Auteur ; Hamid Reza Seyf, Auteur . - 2009 . - 5 p. Fluids engineering Langues : Anglais (eng) in Transactions of the ASME . Journal of fluids engineering > Vol. 130 N° 5 (Mai 2008) . - 5 p. Mots-clés : Fluid  dynamics;  Reynolds  number;  equations;  microchannels;  Navier-Stokes  equations;  pressure;  differential  equations Résumé : Analytical analysis of fluid flow in an annular microchannel subjected to uniform wall injection at various Reynolds numbers is presented. The classical Navier–Stokes equations are used in the present study. Mathematically, using an appropriate change of variable, Navier–Stokes equations are transformed to a set of nonlinear ordinary differential equations. The governing equations are analytically solved using series solution method. Some analytical results are given for the prediction of velocity profiles and pressure distributions in annular microchannels. The agreement between the computational fluid dynamics and the analytical predictions is very good. However, the analytical results are valid in a limited range of radius ratios and needs more study. En ligne : http://fluidsengineering.asmedigitalcollection.asme.org/issue.aspx?journalid=122 [...]

Numerical analysis of convective heat transfer from an elliptic pin fin heat sink with and without metal foam insert / Hamid Reza Seyf in Journal of heat transfer, Vol. 132 N° 7 (Juillet 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 7 (Juillet 2010) . - pp. [071401-1/9] Titre : Numerical analysis of convective heat transfer from an elliptic pin fin heat sink with and without metal foam insert Type de document : texte imprimé Auteurs : Hamid Reza Seyf, Auteur ; Mohammad Layeghi, Auteur Article en page(s) : pp. [071401-1/9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Heat  sink  Porous  media  Mettalic  foam  Numerical  method  Finite  volume Index. décimale : 536 Chaleur. Thermodynamique Résumé : A numerical analysis of forced convective heat transfer from an elliptical pin fin heat sink with and without metal foam inserts is conducted using three-dimensional conjugate heat transfer model. The pin fin heat sink model consists of six elliptical pin rows with 3 mm major diameter, 2 mm minor diameter, and 20 mm height. The Darcy–Brinkman–Forchheimer and classical Navier–Stokes equations, together with corresponding energy equations are used in the numerical analysis of flow field and heat transfer in the heat sink with and without metal foam inserts, respectively. A finite volume code with point implicit Gauss–Seidel solver in conjunction with algebraic multigrid method is used to solve the governing equations. The code is validated by comparing the numerical results with available experimental results for a pin fin heat sink without porous metal foam insert. Different metallic foams with various porosities and permeabilities are used in the numerical analysis. The effects of air flow Reynolds number and metal foam porosity and permeability on the overall Nusselt number, pressure drop, and the efficiency of heat sink are investigated. The results indicate that structural properties of metal foam insert can significantly influence on both flow and heat transfer in a pin fin heat sink. The Nusselt number is shown to increase more than 400% in some cases with a decrease in porosity and an increase in Reynolds number. However, the pressure drop increases with decreasing permeability and increasing Reynolds number. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Numerical analysis of convective heat transfer from an elliptic pin fin heat sink with and without metal foam insert [texte imprimé] / Hamid Reza Seyf, Auteur ; Mohammad Layeghi, Auteur . - pp. [071401-1/9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 7 (Juillet 2010) . - pp. [071401-1/9] Mots-clés : Heat  sink  Porous  media  Mettalic  foam  Numerical  method  Finite  volume Index. décimale : 536 Chaleur. Thermodynamique Résumé : A numerical analysis of forced convective heat transfer from an elliptical pin fin heat sink with and without metal foam inserts is conducted using three-dimensional conjugate heat transfer model. The pin fin heat sink model consists of six elliptical pin rows with 3 mm major diameter, 2 mm minor diameter, and 20 mm height. The Darcy–Brinkman–Forchheimer and classical Navier–Stokes equations, together with corresponding energy equations are used in the numerical analysis of flow field and heat transfer in the heat sink with and without metal foam inserts, respectively. A finite volume code with point implicit Gauss–Seidel solver in conjunction with algebraic multigrid method is used to solve the governing equations. The code is validated by comparing the numerical results with available experimental results for a pin fin heat sink without porous metal foam insert. Different metallic foams with various porosities and permeabilities are used in the numerical analysis. The effects of air flow Reynolds number and metal foam porosity and permeability on the overall Nusselt number, pressure drop, and the efficiency of heat sink are investigated. The results indicate that structural properties of metal foam insert can significantly influence on both flow and heat transfer in a pin fin heat sink. The Nusselt number is shown to increase more than 400% in some cases with a decrease in porosity and an increase in Reynolds number. However, the pressure drop increases with decreasing permeability and increasing Reynolds number. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]

Thermal and hydraulic performance of counterflow microchannel heat exchangers with and without nanofluids / Hamid Reza Seyf in Journal of heat transfer, Vol. 133 N° 8 (Août 2011) 

Public ISBD [article]  in Journal of heat transfer > Vol. 133 N° 8 (Août 2011) . - pp. [081801/1-9] Titre : Thermal and hydraulic performance of counterflow microchannel heat exchangers with and without nanofluids Type de document : texte imprimé Auteurs : Hamid Reza Seyf, Auteur ; Shahabeddin Keshavarz Mohammadian, Auteur Année de publication : 2011 Article en page(s) : pp. [081801/1-9] Note générale : Physique Langues : Anglais (eng) Mots-clés : Numerical  simulation  Nanofluid  Brownian  motion  Effectiveness  Thermal  performance Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper analyzes the thermal and hydraulic performance of a counterflow microchannel heat exchanger (CFMCHE) with and without nanofluid as working fluid. A 3D conjugate heat transfer simulation is carried out using a finite volume approach to evaluate the effects of inlet Reynolds number, Brownian motion, and volume fraction of nanoparticles on the pumping power, effectiveness, and performance index of CFMCHE. The accuracy of the code has been verified by comparing the results with those available in the literature. A single phase approach is used for the nanofluid modeling. The base fluid used in the analyses as a basis for comparison was pure water. Two types of nanofluids, namely, water-Al2O3 with a mean diameter of 47 nm and water-CuO with a mean diameter of 29 nm, each one with three different volume fractions, are utilized. In addition, two temperature dependent models for the thermal conductivity and viscosity of nanofluids that account for the fundamental role of Brownian motion are used. Calculated results demonstrate that the effectiveness and performance index of CFMCHE decrease with increasing Reynolds number. Moreover, it is observed that the relative enhancements in the pumping power become more prominent for higher values of Reynolds numbers. It was also found that the performance index and pumping power are not sensitive to volume fraction at higher and lower Reynolds numbers, respectively. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO00013300 [...] [article] Thermal and hydraulic performance of counterflow microchannel heat exchangers with and without nanofluids [texte imprimé] / Hamid Reza Seyf, Auteur ; Shahabeddin Keshavarz Mohammadian, Auteur . - 2011 . - pp. [081801/1-9]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 133 N° 8 (Août 2011) . - pp. [081801/1-9] Mots-clés : Numerical  simulation  Nanofluid  Brownian  motion  Effectiveness  Thermal  performance Index. décimale : 536 Chaleur. Thermodynamique Résumé : This paper analyzes the thermal and hydraulic performance of a counterflow microchannel heat exchanger (CFMCHE) with and without nanofluid as working fluid. A 3D conjugate heat transfer simulation is carried out using a finite volume approach to evaluate the effects of inlet Reynolds number, Brownian motion, and volume fraction of nanoparticles on the pumping power, effectiveness, and performance index of CFMCHE. The accuracy of the code has been verified by comparing the results with those available in the literature. A single phase approach is used for the nanofluid modeling. The base fluid used in the analyses as a basis for comparison was pure water. Two types of nanofluids, namely, water-Al2O3 with a mean diameter of 47 nm and water-CuO with a mean diameter of 29 nm, each one with three different volume fractions, are utilized. In addition, two temperature dependent models for the thermal conductivity and viscosity of nanofluids that account for the fundamental role of Brownian motion are used. Calculated results demonstrate that the effectiveness and performance index of CFMCHE decrease with increasing Reynolds number. Moreover, it is observed that the relative enhancements in the pumping power become more prominent for higher values of Reynolds numbers. It was also found that the performance index and pumping power are not sensitive to volume fraction at higher and lower Reynolds numbers, respectively. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JHTRAO00013300 [...]

Vapor flow analysis in flat plate heat pipes using homotopy perturbation method / Hamid Reza Seyf in Journal of heat transfer, Vol. 132 N° 5 (Mai 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [054502-1/4] Titre : Vapor flow analysis in flat plate heat pipes using homotopy perturbation method Type de document : texte imprimé Auteurs : Hamid Reza Seyf, Auteur ; Mohammad Layeghi, Auteur Article en page(s) : pp. [054502-1/4] Note générale : Physique Langues : Anglais (eng) Mots-clés : Flat  plate  heat  pipe  Vapor  flow  Laminar  and  incompressible  Homotopy  perturbation  method  Numerical  method Index. décimale : 536 Chaleur. Thermodynamique Résumé : In the present study, an analytical solution for 2D vapor flow in flat plate heat pipes is presented. The governing equations are solved analytically using the homotopy perturbation method, and numerically using the finite volume method, based on collocated grids. The analytical results are obtained for nondimensional velocity profiles and axial pressures distribution along the entire length of the heat pipe, and compared with the numerical ones. It is shown that there is a relatively small difference of about 1% in the worst case between the analytical and numerical results. Furthermore, the effects of the Reynolds number and the ratio of condenser to evaporator lengths on the flow variables are discussed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...] [article] Vapor flow analysis in flat plate heat pipes using homotopy perturbation method [texte imprimé] / Hamid Reza Seyf, Auteur ; Mohammad Layeghi, Auteur . - pp. [054502-1/4]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 5 (Mai 2010) . - pp. [054502-1/4] Mots-clés : Flat  plate  heat  pipe  Vapor  flow  Laminar  and  incompressible  Homotopy  perturbation  method  Numerical  method Index. décimale : 536 Chaleur. Thermodynamique Résumé : In the present study, an analytical solution for 2D vapor flow in flat plate heat pipes is presented. The governing equations are solved analytically using the homotopy perturbation method, and numerically using the finite volume method, based on collocated grids. The analytical results are obtained for nondimensional velocity profiles and axial pressures distribution along the entire length of the heat pipe, and compared with the numerical ones. It is shown that there is a relatively small difference of about 1% in the worst case between the analytical and numerical results. Furthermore, the effects of the Reynolds number and the ratio of condenser to evaporator lengths on the flow variables are discussed. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&smode=strresults& [...]