Discussion Forum

Hi Guys,
I am new to COMSOL and I need your help regarding the permeability estimation. I will describe my project below. (I have drew a simple picture that hopefully illustrate my project).
I have a metal support with 10,000 cylindrical holes and I want to test permeability of the metal support by flowing the air through the metal support, it is assumed to be laminar flow). I know it is unrealistic to draw all 10,000 holes, then do the simulation, therefore I decided to solve the problem by analyzing a unit cell since it is basically repetitive geometry. (I have attached my unit cell)
I did not use the porous media flow module, since it does not really reflect my geometry and my main purpose is to test the permeability of the metal support under the specific geometry I have.
My current problem is setting up the boundary condition. (I am basically using the Darcy's law which is k=porosity*viscosity*linear velocity*length/pressure differential, porosity, viscosity, L and delta P are known. I am using COMSOL to get linear velocity. In the laminar flow section, I applied the periodic flow condition so I can input the pressure differential and it asks me to specify the source and destination. However, since what I have is just a 2D cell which means only the entrance showed up, there is no way to specify them. (I know I must did something wrong)
Again, I am new to COMSOL, I really appreciate any guidance you could give to me and thanks for reading my question