How to set the outlet boundary condition which has two direction.
 

Hi OpenFoamers,
I am new in openFoam and when I try to make a model myself, I found that the boundary conditions can not satisfy the continious situation.
Attachment 70868
In this simple model, the inlet is v=0.1m/s p=zerogradient.
But when it comes to outlet, I tried to use freestream conditions but the flux changes every time and I am not able to calculate it.
I just do not want to calculate the outlet BC.
How should I set the boundary condition of outlet.....

Thanks in advance for any possible advices!

Chen

Without knowing the details of what you are trying to simulate, or the solver you are using, it's hard to give advice on boundary conditions.
For a simple inlet-outlet simulation, p is generally set as a fixed value (0 in incompressible solver, and 101325 in a compressible solver) and U set as zero gradient.