Pressure or body force for porous media

Lattice Boltzmann Method LBM: Theory
#1

Dear Friends,

I tried to use LBGK and MRT model to simulate the permeability of 3D porous media respectively. I read some relative publications and found that most popular implementation of inlet/outlet boundary were Zou/He pressure BC, Martin Hecht pressure BC and body force instead of pressure BC. I implemented them to simulate the fluid flow in 3D porous meida obtained from X-ray CT test. The calculated premeability was much higher than the experiments when I used the former two pressure BC with bounce-back BC. When I used the body force with bounce-back BC, the average flow velocity was turned to be minus (opposite to the flow direction). It think it may be attributed to the low porosity just about 15%. It should be pointed out that I mirrior the porous media to make it really periodic.

Is there anyone have the similar experience and finding? Any suggests and comments are welcom. Thank you.

Regards,

Jack

#2

Hi Jack,

It might be a problem with BB for porous media. The good way is to use TRT/MRT models with BB, otherwise the accuracy of BB boundary depends on the relaxation parameter tau, which can influence your simulations a lot.

Hopefully it will help,
Alex

#3

I am simulating flow of an incompressible fluid between two parallel surfaces. I am using body force driving the flow. When I see the output results, density at all the points is 1. I was wondering how can calculate dynamic pressure at different points. Velocity fields have correct value though.

I am using Palabos and my simulation is 2D.

Thanks,