[Francesca Tedeschi]

Hello,

I have recently started using OpenFoam for internal fluid dynamics simulations. Specifically, I am simulating the flow of compressed air through a convergent-divergent nozzle by imposing a pressure difference (6 bar) between the primary inlet and the outlet, see link https://imgur.com/TEfdhyb.png

From theory, I know that this is not the correct field. I can also compare it with the solution obtained from a very reliable commercial software, which I am sharing the link to here https://imgur.com/YvQNi8S.png

I would be very grateful if any expert could help me improve this solution. If needed, I can attach excerpts from the 0, constant, and system folders.

[rocketLauncher]

Could you post those files? It's important to see what boundary conditions you are imposing in OF and in the commercial software to determine whether they are comparable

[CFD_with_Skill-Lync]

If you can provide insight into the setup, it would be helpful. We'd need to check the boundary conditions to provide resolution. Compressible solvers might be inducing diffusion, we would advise you check the mesh as well.

[Francesca Tedeschi]

Originally Posted by rocketLauncher

Could you post those files? It's important to see what boundary conditions you are imposing in OF and in the commercial software to determine whether they are comparable

Originally Posted by CFD_with_Skill-Lync

If you can provide insight into the setup, it would be helpful. We'd need to check the boundary conditions to provide resolution. Compressible solvers might be inducing diffusion, we would advise you check the mesh as well.

When you say "check the mesh", what do you mean, precisely?
I usually check the minumum orthogonal quality. In this case is, effectively, quite low (<0.1) and I know that could be a problem. But:
1- the region affected by problematic mesh cells was little
2-the simulation ran the same
thus, I proceeded. Do you think this has been such a drastic impact on the final result? I think that this is not the point and that there is some setting (initialization of fields or solvers) wrong. But I don't know what. If you could help me I would be very grateful


I attach the files (BC and setup of both Ansys and OF) you asked for.