resistance b.c.'s in FEM
 

Consider the following: geometry is a bifurcation (Y) inlet: velocity prescribed. 2 outlets: where different resistances are applied R1 smaller than R2. The resistance b.c. is a simple P = Q * R condition where R is a representation for what happens downstream.

I can't get this converged. I get inflow on the outflow.

The resistance b.c. is just the simplest of lumped parameter models that I can think of, and it has a nice electrical analogy.

Can anyone shed some light as to why this is not converging, or give me an idea what to apply instead?

Re: resistance b.c.'s in FEM
 

(1). Install two positive displacement pumps at each outlet. Then you can control the exact flow rate. And the outlet is always the outlet. This is a test setup. (2). With the flow rate specified, you can specify the outlet velocity as boundary conditions. The solution should converge. It is like having a faucet at the end of each outlet, you control the flow rate there.