Learning Forum

[quanhh.ineep]

Dear Forum,nI have my simple fluent without inlet and outlet as shown in the picture below.nI would like to have some questions regarding the setup of the boundary conditions:n- How to set up material properties for air and helium, should I set constant-density or incompressible-ideal-gas or another one?n- How to set the pressure for air and helium because as you can see that the helium pressure is 0.75MPa while air pressure is 0.1Mpa.nThank you in advance for your kind helps,n

[Amine Ben Hadj Ali]

If it is closed: Use Ideal Gas Law for both. Boussinesq will also conserve mass but I do not recommend it here (unless if you have small temperature differences)nRun transient and patch the pressure field in the Helium Zone. Say define the operating pressure to be 1 Atm and patch the pressure in helium zone to to 0.65MPa.n

[quanhh.ineep]

Dear Sir,nThank you a lot for your kind help,nI have tried to patch the pressure in the Helium Zone as you said as follow:nHowever, when I checked the pressure of the Helium zone, it seems the pressure does not change.nCould you please tell me how to fix this problem?nBtw, regarding the viscosity, please suggest to me which model is suitable for my problem? Laminar or k-epsilon?nThank you,

[Amine Ben Hadj Ali]

You said have 0.65 MPa and you are patching few Pascals...nIf you do not know if your flow is laminar or turbulent or on his way to transition from laminar to turbulent it is always safe to rely on SST Model.n

[quanhh.ineep]

Thank you for your quick response,nI set few Pascals just an example, the other value gave the same results in which the pressure did not change. Could you please help me to fix this problem?nI will modify the viscous model to SST Model as your suggestion.nn

[Amine Ben Hadj Ali]

1/Model both as Ideal Gas GAsn2/Use Transient SolvernBoth points I have written from beginning. After that check the pressure field (the static pressure and not the Absolute)n

[quanhh.ineep]

I have tried to set the B.C as you said but still cannot patch the pressure. I would like to upload my case file, I am very much appreciated if you could check it. I compress the file to 7z to be able to upload. So please extract to .gz.nThank you very much!nn

[Amine Ben Hadj Ali]

I apologize but as Ansys Employee I won't check your attachment. Can you copy paste the screenshots of the steps you are following? n

[Amine Ben Hadj Ali]

Closed domain to maintain mass conservation please use the suggested density definitions.n