This study simulates natural convection flow resulting from heat partitions in an H-shaped enclosure filled with a nanofluid using an incompressible smoothed particle hydrodynamics(ISPH)method.The right area of the H-...This study simulates natural convection flow resulting from heat partitions in an H-shaped enclosure filled with a nanofluid using an incompressible smoothed particle hydrodynamics(ISPH)method.The right area of the H-shaped enclosure is saturated with non-Darcy porous media.The center variable partitions of the H-shaped enclosure walls are kept at a high-temperature Th.The left and right walls of the H-shaped enclosure are positioned at a low temperature Tc and the other walls are adiabatic.In ISPH method,the source term in pressure Poisson equation(PPE)is modified.The influences of the controlling parameters on the temperature distributions,the velocity field and average Nusselt number are discussed.The performed simulations proofed that the length of the heated partitions augments the velocity field and temperature distributions in an H-shaped enclosure.Rayleigh number rises the fluid velocity and heat transfer in an H-shaped enclosure.The porous layer on the right side of the H-shaped enclosure at a lower Darcy parameter causes a high resistance force for the fluid flow and heat transfer characteristic inside an H-shaped enclosure.Added nanoparticles reduces the velocity field and enhances the heat transfer inside an H-shaped enclosure.展开更多
A numerical study has been carried out to investigate the temperature distribution and the natural convection heat transfer in axisymmetric two-dimensional vertical saturated porous cylinder with steady state laminar ...A numerical study has been carried out to investigate the temperature distribution and the natural convection heat transfer in axisymmetric two-dimensional vertical saturated porous cylinder with steady state laminar flow. A comparison between two situations is done under the effect of MHD （magnetohydrodynamics） and radiation. In the two situations, the vertical walls of the cylinder are cooled with constant wall temperature and a constant heat generation subjected along the centerline of the cylinder. The first case for cylinder with insulated upper surface and cooled bottom surface while the second case for cylinder with cooled upper surface and insulated bottom surface. The governing equations used are continuity, momentum and energy equations which are transformed to dimensionless equations. The finite difference approach is used to obtain all the computational results using the MATLAB-7 programming. The parameters affected the system are Rayleigh number ranging within （102≤ Ra ≤104）, radiation parameter （0≤ Rd ≤ 2） and magnetohydrodynamics MHD （Mn） （0 ≤ Mn≤ 2）.The results show that the temperature of Case 1 is more than that in Case 2 at constant Ra, Mn and Rd while the value of the stream in Case 2 is greater than that in Case 1. Nu increase with the increase of Rd and increasing Mn caused the temperature to increase and the streamline dropped while Nu decreased. A correlation has been set up to give the average Nusselt number variation with Ra, Rd and Mn for which the results are found to be in good agreement with previously published researches.展开更多
Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is a...Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the H boundary condition in the terminology of Kays and Crawford [12], is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. Having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio （width to height ratio）. These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case by Ratts and Rant [14].展开更多
基金The authors would like to extend their appreciations to the Deanship of Scientific Research at King Khalid University,Abha,Saudi Arabia,for funding this work through the Research Group Project under Grant Number(R.G.P 2/70/41).
文摘This study simulates natural convection flow resulting from heat partitions in an H-shaped enclosure filled with a nanofluid using an incompressible smoothed particle hydrodynamics(ISPH)method.The right area of the H-shaped enclosure is saturated with non-Darcy porous media.The center variable partitions of the H-shaped enclosure walls are kept at a high-temperature Th.The left and right walls of the H-shaped enclosure are positioned at a low temperature Tc and the other walls are adiabatic.In ISPH method,the source term in pressure Poisson equation(PPE)is modified.The influences of the controlling parameters on the temperature distributions,the velocity field and average Nusselt number are discussed.The performed simulations proofed that the length of the heated partitions augments the velocity field and temperature distributions in an H-shaped enclosure.Rayleigh number rises the fluid velocity and heat transfer in an H-shaped enclosure.The porous layer on the right side of the H-shaped enclosure at a lower Darcy parameter causes a high resistance force for the fluid flow and heat transfer characteristic inside an H-shaped enclosure.Added nanoparticles reduces the velocity field and enhances the heat transfer inside an H-shaped enclosure.
文摘A numerical study has been carried out to investigate the temperature distribution and the natural convection heat transfer in axisymmetric two-dimensional vertical saturated porous cylinder with steady state laminar flow. A comparison between two situations is done under the effect of MHD （magnetohydrodynamics） and radiation. In the two situations, the vertical walls of the cylinder are cooled with constant wall temperature and a constant heat generation subjected along the centerline of the cylinder. The first case for cylinder with insulated upper surface and cooled bottom surface while the second case for cylinder with cooled upper surface and insulated bottom surface. The governing equations used are continuity, momentum and energy equations which are transformed to dimensionless equations. The finite difference approach is used to obtain all the computational results using the MATLAB-7 programming. The parameters affected the system are Rayleigh number ranging within （102≤ Ra ≤104）, radiation parameter （0≤ Rd ≤ 2） and magnetohydrodynamics MHD （Mn） （0 ≤ Mn≤ 2）.The results show that the temperature of Case 1 is more than that in Case 2 at constant Ra, Mn and Rd while the value of the stream in Case 2 is greater than that in Case 1. Nu increase with the increase of Rd and increasing Mn caused the temperature to increase and the streamline dropped while Nu decreased. A correlation has been set up to give the average Nusselt number variation with Ra, Rd and Mn for which the results are found to be in good agreement with previously published researches.
文摘Effect of temperature-dependent viscosity on fully developed forced convection in a duct of rectangular cross-section occupied by a fluid-saturated porous medium is investigated analytically. The Darcy flow model is applied and the viscosity-temperature relation is assumed to be an inverse-linear one. The case of uniform heat flux on the walls, i.e. the H boundary condition in the terminology of Kays and Crawford [12], is treated. For the case of a fluid whose viscosity decreases with temperature, it is found that the effect of the variation is to increase the Nusselt number for heated walls. Having found the velocity and the temperature distribution, the second law of thermodynamics is invoked to find the local and average entropy generation rate. Expressions for the entropy generation rate, the Bejan number, the heat transfer irreversibility, and the fluid flow irreversibility are presented in terms of the Brinkman number, the Péclet number, the viscosity variation number, the dimensionless wall heat flux, and the aspect ratio （width to height ratio）. These expressions let a parametric study of the problem based on which it is observed that the entropy generated due to flow in a duct of square cross-section is more than those of rectangular counterparts while increasing the aspect ratio decreases the entropy generation rate similar to what previously reported for the clear flow case by Ratts and Rant [14].
