Help with pressure boundary conditions
Hi everybody.
I need a bit of help with boundary conditions. I am performing a 1-way fsi in fluent. I have a balloon-like structure that contracts, expelling fluid out of an opening. This balloon then expands, drawing fluid back into the balloon through the same opening. I am currently modelling this opening as a pressure-outlet boundary condition. My model is converged but at the transition between contraction and expansion there is a discontinuity in the flow and pressure fields (i am assuming that the discontinuity in the flow is produced because of the pressure discontinuity). I do not really understand how the pressure-outlet works I assumed it just set a 0 gauge pressure at the boundary and so was effectively and 'opening' condition like what is offered in CFX. Does the pressure-outlet boundary have difficulty with revered flow? Can anyone think of a boundary condition that would be better for my model? I wanted to try pressure far-field but the option does not seems to be there. Any help is greatly appreciated. I am using a coupled solver scheme, PRESTO! for the pressure interpolation and a second order upwind scheme for momentum. Cheers Stephen Waite |
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