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-   -   Pressure divergence with interTrackFoam (http://www.cfd-online.com/Forums/openfoam-solving/57861-pressure-divergence-intertrackfoam.html)

virginie_e March 2, 2009 08:11

Hello, I am using interTra
 
Hello,

I am using interTrackFoam to simulate the flow of a fluid which first slides along a slope and then falls freely in a basin. The simulation runs fine until a while. The pressure of the fluid at the point where the slope stops and the fluid falls freely begins to diverge. Could someone give me some advice about how I could fix this problem?

I am using laplaceFaceDecomposition solver for the mesh motion and I did not change the coefficients for the solving of U and p from the hydrofoil tutorial.

If you need some more information, just tell me.

Thank you a lot in advance

Virginie

deepsterblue March 2, 2009 14:04

Could you post a few pictures?
 
Could you post a few pictures? Preferably wire-frame images.

virginie_e March 3, 2009 03:46

Hello Sandeep, Here are a
 
Hello Sandeep,

Here are a few pictures. There are the pressure plot, the velocity plot and a zoom on the part where the pressure diverges.
The inlet is the upper left corner, the outlet is the lower right corner. The fluid flows down the "spout" then falls freely over a bath of liquid tin. I simulated the tin with a boundary pressure condition over the free surface.


http://www.cfd-online.com/OpenFOAM_D...es/1/11457.jpg




http://www.cfd-online.com/OpenFOAM_D...es/1/11458.jpg



http://www.cfd-online.com/OpenFOAM_D...es/1/11459.jpg


As you can see the pressure diverges right at the point where the fluid leaves the slope and falls freely. And there does not seem to be any mesh problems… They only come after a while. I wonder if I choose a wrong pressure solver… Could you please give me some advice about it? Thanks a lot.

Virginie

virginie_e March 3, 2009 04:39

Here is my case directory if y
 
Here is my case directory if you want to have a look.

Here is what I do:
fluentMeshToFoam tinpressure.mah
makeFaMesh
interTrackFoam



Thank you for your help!

Virginie

virginie_e March 3, 2009 04:49

Oups, sorry I did not atta
 
Oups,

sorry I did not attach the files correctly

http://www.cfd-online.com/OpenFOAM_D...s/mime_zip.gif tinpressurecopy.zip

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif tinpressure.msh.gz

virginie_e March 3, 2009 04:58

Sorry I also forgot my library
 
Sorry I also forgot my library for the pressure condition on the free surface (p=0 above the tin level, otherwise p = rho*g*z basically)

http://www.cfd-online.com/OpenFOAM_D...s/mime_zip.gif linearTinPressurePerso.zip

deepsterblue March 3, 2009 14:53

I only see an entry for SIMPLE
 
I only see an entry for SIMPLE in fvSolution - is this a steady-state type of simulation? You might want to have a time step restriction using the Courant number too. For bad meshes, you might want to increase the number of nonOrthogonal correctors.

Also, the mesh looks like it was obtained from a previous calculation. Surface tension might behave erratically if the surface normals are ill-behaved.

virginie_e March 4, 2009 03:20

Thank you Sandeep for your qui
 
Thank you Sandeep for your quick answer.

I have alreday tried to increase the number of nonOrthogonal correctors but I had the same divergence.
I will try though the time step restriction using the Courant number. That is a good idea.

Yes it is indeed a steady-state type of simulation. Is there a kind of option which I should set? If yes, what kind of option?

Anyway, thanks for your help.

virginie_e March 4, 2009 05:07

Hello, I have tried to set
 
Hello,

I have tried to set a time step restriction using the Courant number and to increase teh number of nonOrthogonal correctors (30) but I still get the same kind of error. Have you got some other ideas about what I should do?

Otherwise, do you know where I could find some documentation about all the available options that are implemented for SIMPLE? I have tried to search for it but I could not find anything.

Thank you for your time.


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