[Werl]

Hi Everyone,

I am new to this forum but I wanted to reach out as I have been working on this project for a while and have been having a lot of problems with this simulation. Essentially, I am using CFD (Fluent) to simulation a tube that is slowly being compressed. I am trying to determine the max possible flow rate going through the tube at the given pressure. I have used a CAD model with parameters and an ellipse relationship to mimic the tube being compressed.

I have set up the system with a pressure inlet and outlet as these are the only known real world conditions. However the problems come when I try to run the simulation.

- If I use a Quad mesh I find that the solution is unable to converge when the tube is half closed. The continuity variable will diverge. If I try to shrink the mesh it will crash and be unable to render the mesh.

- When I switch to a tetrahedral mesh the solution will start to converge and then the residuals will plateau at a specific number. However, the results will show issues with the pressure inlet. For example, the pressure given by the simulation for the inlet doesn't match the boundary condition.

I have tried running the simulation with both laminar and turbulent models as well as pressure and density based simulations. However I continue to get the same results. The inlet an outlet pressure are 4psi and 0psi respectively.

I was wondering if anyone had any tips regarding this issue. Any help would be appreciated.

Thanks everyone!

[duri]

Need more information to understand the problem.
Is the fluid through the pipe compressible or incompressible?
Where are you compressing the tube. Is it near outlet or mid or inlet?
When the tube is closed, does it result in choking?