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-   -   interPhaseChangeFoam bad results (https://www.cfd-online.com/Forums/openfoam-solving/174689-interphasechangefoam-bad-results.html)

brg_mohajer July 17, 2016 15:39

interPhaseChangeFoam bad results
 
2 Attachment(s)
I am trying to simulate a cavitating flow over 290C hydrofoil. I have to do it with interPhaseChangeFoam version 2.3.0. I was able to perform the simulation with cavitatingFoam with good results. however, for my project I need Schnerr-Sauer mass transfer equation with IPCF which is a big pain in my neck now.
the flow either never cavitates or diverges at some specific cells of my mesh with super high pressure.
I modified the mesh with different schemes and tried different boundary conditions; V-driven, P-driven, etc. and yet no acceptable result:-(
I am stuck and I have now idea what to do. any help is highly appreciated.

my project is modelling LN2 over this hydrofoil. therefore, I prepared a solver based on IPCF with the energy equation. if you think the problem can be the new solver itself it will be available within the attachments for anyone helping me. However, i tested my case with IPCF and I think the problem is not related to my code.

charitonas August 6, 2016 17:56

CavitatingFoam reflecting boundaries
 
Hi,

I would like to run a case of throttle with cavitation.I do have high pressures as an inlet and i was wondering what should be my boundary conditions since there is a reflection if a leave the case to run for a long time?Another question is where should that case stop since it does not converge because of the reflection?

Thank you in advance

Chariton

brg_mohajer August 16, 2016 06:33

1 Attachment(s)
Hi Charitonas,
I cab tell you what I did:
A pressure driven boundary condition is working well with cavitatingFoam even with high pressure values. The only case is when you have serious comprehensibility issues that this solver neglects while it must not. I don't think if it is your case.
I attached a zero folder to this message. it is related to Barış Biçer's nozzle.

For the convergence, it is only the matter of your experience. the eoncerging time varies strongly with the geometry and turbulence model.
I added a code to my own solver in order to write the mass flow rates of the outlet and the inlet. hence, I could see that the flow is converged or not. However, nothing can substituted the visual check of the time steps in paraFoam.
in conclusion I think it is better to set a long endTime and continue checking the results each and every while by yourself.

let me know if you also find any solution for my problem plz.

Regards,
Behrang

charitonas August 17, 2016 04:39

Hi Behrang,

Thank you for your reply. I have already tested these boundary conditions and i have seen that there is actually a reflection of pressure (and velocity) on the boundaries. Do you think that i should increase the computational domain? ie going from cm to m?

Thanks again,
Chariton

brg_mohajer August 18, 2016 14:07

I ask you some questions beside asserting my opinions within this message:
I do NOT think that the source of P reflection is due to the mesh resolution, unless you have a very irregular shapes on the refinement region boundaries; such as strange triangles. therefore you will see internal pressure swings and not close to the boundaries. in these cases you need to modify the mesh.
On the other hand, usually the sources of P reflections in are the outlets;is this issue beginning from your outlet? if yes, you need to modify the outlet BC on P and U OR to modify the dummy outlet. moreover, you can try interPhaseChangeFoam.

which version of openFoam are you using? mine is 2.3.0
are you working on the same RAS folder among the tutorials?
if not, can you send me your case with some animations?
brg_mohajer@yahoo.com


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