Discussion Forum

Hello,

My geometry consists of two explicit domains (fluid domain, cell domain) and one explicit boundary (cell walls). I'm solving for the shear induced velocity field in the fluid domain using the Fluid & Porous Media Flow Interface in steady state. Since, my fluid is a water soluble drug that is transferred through convection and diffusion inside the cell domains, I have setup 2 Mass Transport Equations. The 1st one is for the fluid domain, where the velocity field solution is used in the convective term and the 2nd one is for the cell domains, where the drug is transferred through diffusion and there is metabolized through a Reaction BC applied inside the cells.

There is an empirical relation that describes that effect of the Average Wall Shear Stress on the Cell Boundaries AVG WSS = avg (sqrt (fp.Tstressx^2+fp.Tstressy^2)) versus the Reaction Term R and has the form R = k* AVG_WSS, where k could be for example equal to 3.

Thus, I want to implement a Reaction BC for the 2nd Mass Transfer Equation (cell domains), which is going to use the average solution of WSS around each cell coming form the Fluid & Porous Media Flow Interface.
R = 3*AVG_WSS

I tried to do that, by creating a local variable WSS and then incorporate in the Reaction BC.
However, I'm receiving the error shown in the attached file together with my model.

Is it possible somehow to connect the WSS around each cell with the Reaction Boundary Node?
Or in other words is possible to use the solution values on an explicit boundary coming from the physics of one domain, as an argument of an expression used as BC for another domain. The two domains (fluid domain, cell domains) are distinguished by this common boundary (cell boundary).

Can this be done with a General Extrusion?
Can this e done with a Global Equation somehow?
I've seen some posts, where people try to transmit solutions between 2 different models, but they are not so informative.

Any help will be greatly appreciated!!!

Best,
Filippos