June 22-27, 2014
The effects of variable porosity and variable thermal conductivity of the medium and also the emission, absorption and scattering of radiation are studied in this paper. The comparative study has been made for three different situations, namely a) variable porosity b) constant porosity and c) absence of porous medium.In carrying out the solution, the momentum and energy equations are coupled and they are solved simultaneously by Runge-Kutta Gill method in conjunction with Newton-Raphson iterative scheme. The results of the analyses show that, in the cases of variable porosity and absence of porous medium the velocity profiles possess very small curvature at the wall, whereas, in the case of constant porosity situation the velocity profile is almost zero upto a certain distance and then increases. Nevertheless, it reaches unity asymptotically in all the three cases. The temperature profile becomes linear as the value of b (ratio of thermal conductivity of solid to fluid –λs/λf) increases. Another important result of the analysis is that the rise in temperature in variable porosity medium is about 25% more in comparison with absence of porous medium. Further, the results show that the total heat flux in the variable porosity medium is about 79% more as compared to constant porosity medium. And the variable conductivity enhances the total heat flux by about 33% as compared to constant conductivity of the medium.
Puttabasavsetty Nagaraju, "Effect of variable porosity on composite heat transfer in a boundary layer flow" in "5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry", Prof. Kambiz Vafai, University of California, Riverside; Prof. Adrian Bejan, Duke University; Prof. Akira Nakayama, Shizuoka University; Prof. Oronzio Manca, Seconda Università degli Studi Napoli Eds, ECI Symposium Series, (2014). http://dc.engconfintl.org/porous_media_V/28