Numerical study of heat transfer in an optically thick semi-transparent spherical porous medium

2005 ◽  
Vol 91 (3) ◽  
pp. 363-372 ◽  
Author(s):  
B. Chérif ◽  
M.S. Sifaoui
2020 ◽  
Vol 7 ◽  

This paper studies the effects of Hall and ion slip on two dimensional incompressible flow and heat transfer of an electrically conducting viscous fluid in a porous medium between two parallel plates, generated due to periodic suction and injection at the plates. The flow field, temperature and pressure are assumed to be periodic functions in ti e ω and the plates are kept at different but constant temperatures. A numerical solution for the governing nonlinear ordinary differential equations is obtained using quasilinearization method. The graphs for velocity, temperature distribution and skin friction are presented for different values of the fluid and geometric parameters.


2002 ◽  
Vol 27 (4) ◽  
pp. 543-560 ◽  
Author(s):  
C. Ben Kheder ◽  
B. Cherif ◽  
M.S. Sifaoui

2019 ◽  
Vol 9 (2) ◽  
pp. 211 ◽  
Author(s):  
Filiz Ozgen ◽  
Yasin Varol

The heat transfer of mixed convection in a horizontal channel filled with a porous medium has been studied in this article, given that it plays an extensive role in various technical applications, such as flow of fluid in geothermal resources, formations in chemical industries, the storage of radioactive nuclear waste material, and cooling. Those equations written in a dimensionless form have been solved using the finite difference method for different values of the parameters. The results obtained from the study have been presented through streamlines, isotherms, and both local and average Nusselt numbers. It has been observed that parameters such as the Rayleigh and Peclet numbers have an effect on flow and temperature fields.


1994 ◽  
Vol 116 (2) ◽  
pp. 465-472 ◽  
Author(s):  
A. Hadim

A numerical study is performed to analyze steady laminar forced convection in a channel filled with a fluid-saturated porous medium and containing discrete heat sources on the bottom wall. Hydrodynamic and heat transfer results are reported for two configurations: (1) a fully porous channel, and (2) a partially porous channel, which contains porous layers above the heat sources and is nonporous elsewhere. The flow in the porous medium is modeled using the Brinkman-Forchheimer extended Darcy model. Heat transfer rates and pressure drop are evaluated for wide ranges of Darcy and Reynolds numbers. Detailed results of the evolution of the hydrodynamic and thermal boundary layers are also provided. The results indicate that as the Darcy number decreases, a significant increase in heat transfer is obtained, especially at the leading edge of each heat source. For fixed Reynolds number, the length-averaged Nusselt number reaches an asymptotic value in the Darcian regime. In the partially porous channel, it is found that when the width of the heat source and the spacing between the porous layers are of the same magnitude as the channel height, the heat transfer enhancement is almost the same as in the fully porous channel while the pressure drop is significantly lower. These results suggest that the partially porous channel configuration is a potentially attractive heat transfer augmentation technique for electronic equipment cooling, an end that motivated this study.


2019 ◽  
Vol 23 (3 Part B) ◽  
pp. 1861-1873
Author(s):  
Thangavelu Mahalakshmi ◽  
Nagarajan Nithyadevi ◽  
Hakan Oztop

This present numerical study explores the MHD mixed convective flow and heat transfer analysis in a square porous enclosure filled with nanofluid having center thin heater. The left and right walls of the enclosure are maintained at temperature T . The bottom wall is c considered with a constant heat source whereas the remaining part of bottom wall and top wall are kept adiabatic. The finite volume method based on SIMPLE algorithm is used to solve the governing equations in order to investigate the effect of heater length, Hartmann, Richardson, and Darcy numbers on the fluid-flow and heat transfer characteristics inside the enclosure. A set of graphical results are presented in terms of streamlines, isotherms, mid height velocity profiles and average Nusselt numbers. The results reveal that heat transfer rate increases as heater length increases for increasing Darcy and Richardson numbers. Among the two positions of heaters, larger enhancement of heat transfer is obtained for horizontal heater of maximum length. It is observed that, Hartmann number is a good control parameter for heat transfer in fluid-flow through porous medium in enclosure. Moreover, Ag-water nanofluid has greater merit to be used for heat transfer enhancement. This problem may be occurred in designing cooling system for electronic equipment to maximize the efficiency with active and secured operational conditions.


Author(s):  
Ali Mokhtari Nahal ◽  
Mohammad Hassan Nobakhti ◽  
Cyrus Aghanajafi ◽  
Morteza Khayat

In this study, a numerical study is performed on the cooling phenomenon of three heat source electronic devices. The electronic devices are cooled in the form of natural heat transfer by the airflow in a porous medium. Electronic devices are installed on the boundary walls of a square environment. Cooling simulations are performed by drawing flow lines and constant temperature lines. Our main goal is to find the highest cooling rate in different Darcy numbers and different Rayleigh numbers in our investigation. The range of Darcy numbers and Rayleigh numbers is between 0.0001 to 0.01 and 1000 to 100,000, respectively. Our investigation showed the maximum cooling is obtained at the Darcy number of about 0.01. And also, by decreasing the value of Darcy number, a higher cooling rate for the hot boundary walls is achieved.


Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hamid Shafiee ◽  
Elaheh NikzadehAbbasi ◽  
Majid Soltani

The magnetic field can act as a suitable control parameter for heat transfer and fluid flow. It can also be used to maximize thermodynamic efficiency in a variety of fields. Nanofluids and porous media are common methods to increase heat transfer. In addition to improving heat transfer, porous media can increase pressure drop. This research is a computational simulation of the impacts of a magnetic field induced into a cylinder in a porous medium for a volume fraction of 0.2 water/Al2O3 nanofluid with a diameter of 10 μm inside the cylinder. For a wide variety of controlling parameters, simulations have been made. The fluid flow in the porous medium is explained using the Darcy-Brinkman-Forchheimer equation, and the nanofluid flow is represented utilizing a two-phase mixed approach as a two-phase flow. In addition, simulations were run in a slow flow state using the finite volume method. The mean Nusselt number and performance evaluation criteria (PEC) were studied for different Darcy and Hartmann numbers. The results show that the amount of heat transfer coefficient increases with increasing the number of Hartmann and Darcy. In addition, the composition of the nanofluid in the base fluid enhanced the PEC in all instances. Furthermore, the PEC has gained its highest value at the conditions relating to the permeable porous medium.


2020 ◽  
pp. 332-332 ◽  
Author(s):  
Sohail Ahmad ◽  
Muhammad Ashraf ◽  
Kashif Ali

Researchers have significantly contributed to heat transfer field and always made out much effort to find new solutions of heat transfer augmentation. In the concerned work, we have presented a novel study regarding heat and mass transfer flow of nanofluid in the presence of gyrotactic microbes through a porous medium past a stretching sheet. The nonlinear coupled ODEs are obtained after applying the persuasive tool of similarity transformation on governing model PDEs and then tackled numerically by exploiting the SOR (Successive over Relaxation) parameter method. The outcomes of assorted parameters for the flow are surveyed and discussed through graphs and tables. A graphical comparison is correlated with previously accomplished study and examined to be in an exceptional agreement. The culminations designate that the bioconvection Peclet number and microorganism concentration difference parameter enhance density of the motile microorganisms. Moreover, porosity parameter substantially increases shear stress on sheet surface. The addition of nanoparticles in microorganisms is beneficial to improvise the thermal efficiency of many systems like bacteria powered micro-mixers, microfluidics devices like micro-volumes and enzyme biosensor, microbial fuel cells and bio-microsystems like chip-shaped microdevices.


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