An example of such a phenomenon is the flow of species (both gas phase and liquid phase) through GDL (Gas Diffusion Layer) in PEM fuel cells. You can find corresponding governing equations in simulation/modeling papers in this record.

Mr. Vivek Kumar

with my greeting

Mr. Mohammad Hafttananian send to you a perfect answer,

you can find the governing equations and empirical and experimental equations that represent the heat transfer coefficient for the composite porous media in the Manuel guide of fluent,

for the composite porous media you need at first to define and calculate the thermal conductivity for the composite material.

Dear Vivek Kumar,

I don't really understand your question. Please tell us more in detail...

There are quite a few papers which consider the onset of convection in layered porous media. The authors of these papers include McKibbin, Tyvand, Riley, Rees, Georghitza, O'Sullivan, Masuoka. Others have considered cavity convection with heating from the side and with a vertical interface between two different media. It should be quite straightforward to do the literature survey.