# velocity BC for pourous wall (pressure dependendend darcy law)

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 May 19, 2017, 10:40 velocity BC for pourous wall (pressure dependendend darcy law) #1 New Member   Stefan Join Date: Oct 2015 Posts: 24 Rep Power: 10 Dear FOAMers, i wanna investigate a dead end pipe with some porous areas at the wall. The porosity variates along the axis, so I will divide the wall in different parts and each part sould get an individual BC depending on the local porosity. At the inlet of the pipe I will define a pressure BC. Simulation will be steady-state. My goal is to analyze the averaged leakage for each part of the wall. I don't wanna simulate the outside of the pipe. I just wanan look at the massflow through the porous wall(s) (which will be treated like an outlet patch). The fluid is incompressible so i get the massflow with u*rho*area of the wall. Therefore I'm looking for a velocity BC for porous walls which follows darcys law. I thought of setting atm pressure at the wall as p-BC. The velocity BC should calculate the preassure drop between in and outside the pipe (according to the results of the flow field inside) and use a manually given permeability factor k, to calculate the velocity. Simplified u=deltaP*k (normal to the wall) u=0 (not normal to the wall => there should be shearing) in the end it is the exact oppposite of the slip condition: There, the normal component is zero (sliding). It would be a wall (no fluxes can pass) but there is finally no shearing based on the fact that we assume that there are no viscous effect. I had a look through the provided BC of OpenFOAM but could not find a suitable one for my problem. I also searched in the forum - no success. May some of you could help me out which one i have to use, or, in case there isn't such a BC, which one shound be suitable for start programming by myself. Thanks a lot Stefan

 May 29, 2017, 07:53 BC pourous wall #2 New Member   Stefan Join Date: Oct 2015 Posts: 24 Rep Power: 10 Hi again, nobody got an idea according this problem? It would help a lot. Thank you.

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