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problem for centrifugal pump transient simulation |
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May 11, 2013, 12:02 |
problem for centrifugal pump transient simulation
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#1 |
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Hi, all,
Recently, I try to simulate the transient inner flow of centrifugal pump by PimpleDyMFoam on OpenFOAM-2.1.0. But it always ended with the floating point exception error after some steps. I looked into the internal Field of my case by Ensight software and I found that there was a wrong pressure distribution in this centrifugal pump, although the directions of both velocity at inlet and velocity at outlet are right and the direction of impeller rotation is also right. I don't know why it was this? Can someone give me some hints? I will be very appreciated it! In order to explain my questions better, I give the pressure distributions of this pump with steadystate and transient simulation at the first output time step, respectively. Here are: Attachment 21641,Attachment 21642 The boundary file: boundary.txt The fvSchemes file: fvSchemes.txt The fvSolution file: fvSolution.txt The controlDict file: controlDict.txt The initial BCs: Code:
FoamFile { version 2.0; format ascii; class volVectorField; location "3500"; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField nonuniform List<vector> 1196068 ( (0.716798 0.840057 -7.4744) (0.638485 0.861783 -7.48279) (0.681562 0.835391 -7.58056) ... ... wall { type fixedValue; value nonuniform List<vector> 88020 ( (0 0 0) (0 0 0) (0 0 0) ... ... wallimp4 { type movingWallVelocity; value uniform (0 0 0); } wallimp3 { type movingWallVelocity; value uniform (0 0 0); } wallimp2 { type movingWallVelocity; value uniform (0 0 0); } wallimp1 { type movingWallVelocity; value uniform (0 0 0); } outlet { type zeroGradient; } inlet { type fixedValue; value uniform (0 -2.708 0); } } Code:
FoamFile { version 2.0; format ascii; class volScalarField; location "3500"; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField nonuniform List<scalar> 1196068 ( 0.38443 0.248261 0.21847 ... ... wall { type zeroGradient; } wallhgb { type zeroGradient; } wallqgb { type zeroGradient; } interafcevol1 { type cyclicAMI; value nonuniform List<scalar> 1446 ( 5.50122 5.60699 5.11278 ... ... interfacevol { type cyclicAMI; value nonuniform List<scalar> 22196 ( -92.0152 -109.644 -123.262 ... ... interfacesuc { type cyclicAMI; value nonuniform List<scalar> 2368 ( -675.839 -676.411 -675.763 ... ... interfaceimp1 { type cyclicAMI; value nonuniform List<scalar> 1120 ( -676.74 -675.488 -676.987 ... ... interfaceimp { type cyclicAMI; value nonuniform List<scalar> 8680 ( -105.911 -104.788 -102.254 ... ... interfaceckyc { type cyclicAMI; value nonuniform List<scalar> 748 ( -6.02945 -7.33232 -6.99204 ... ... outlet { type fixedValue; value uniform 0; } inlet { type zeroGradient; } } Yun Ren Last edited by renyun0511; May 11, 2013 at 12:23. |
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May 11, 2013, 12:15 |
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#2 |
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Some description for the above attached pictures:
the pressure distribution by steady-state simulation, that is, Time=0s: Attachment 21641 the pressure distribution by transient simulation, that is, Time=0.00005s: Attachment 21642 |
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May 11, 2013, 14:40 |
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#3 |
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Niels Nielsen
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Try with these
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Linnemann PS. I do not do personal support, so please post in the forums. |
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May 11, 2013, 23:50 |
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#4 |
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Hi, Linnemann,
Thank you very much for your reply, but I'm afraid I can only open the fvSolution.txt file. There is something wrong with fvSchemes.txt. Can you uploaded it again? Regards, Yun Ren |
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May 12, 2013, 04:02 |
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#5 |
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Niels Nielsen
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Here we go again
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Linnemann PS. I do not do personal support, so please post in the forums. |
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May 12, 2013, 08:11 |
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#6 |
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Hi, Linnemann,
I'm afraid that " Gauss faceMDLimited 1" is not a valid scheme in Version-2.1.0. When I added it in my original fvSchemes file, there is an error occured: Code:
[0] --> FOAM FATAL IO ERROR: [0] Unknown discretisation scheme faceMDLimited Valid schemes are : 59 ( Gamma GammaV LUST MUSCL MUSCLV Minmod MinmodV OSPRE OSPREV Phi QUICK QUICKV SFCD SFCDV SuperBee SuperBeeV UMIST UMISTV biLinearFit blended clippedLinear cubic cubicUpwindFit downwind filteredLinear filteredLinear2 filteredLinear2V filteredLinear3 filteredLinear3V fixedBlended limitWith limitedCubic limitedCubicV limitedLinear limitedLinearV limiterBlended linear linearFit linearPureUpwindFit linearUpwind linearUpwindV localBlended localMax localMin midPoint outletStabilised pointLinear quadraticFit quadraticLinearFit quadraticLinearUpwindFit quadraticUpwindFit reverseLinear skewCorrected upwind vanAlbada vanAlbadaV vanLeer vanLeerV weighted ) Regards, Yun Ren |
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May 13, 2013, 02:37 |
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#7 |
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Niels Nielsen
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Hi
Im sorry was writing based on memory and the memory was wrong :-) here is the correct syntax Code:
faceMDLimited Gauss linear 1;
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May 13, 2013, 11:13 |
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#8 |
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Hi, Linnemann,
I changed the fvSchemes and fvSolution as you uploaded, but there is error about "mpi". So, I changed little by little, and finally, I found that it is wrong with the relaxationFactors: Here is yours: Code:
relaxationFactors { fields { "p.*" 0.3; } equations { "U.*" 0.7; "k.*" 0.5; "omega.*" 0.5; } } Code:
relaxationFactors { fields { } equations { "U.*" 1; } } At last, when I use your fvSchemes instead of mine and my fvSolution, the result didn't changed a little. Regards, Yun Ren |
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January 15, 2014, 05:55 |
Why only few timesteps in transient simulation
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#9 |
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Bitte56
Join Date: Mar 2013
Location: India
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Dear all,
I am having fundamental question regarding steady and transient simulation. In steady sim, it takes around 100 to 150 iterations to solve a perticular problem. any problm for instance. But while doing transient sim, we give maximum coefficient loops i.e max iterns per timestep as 5 or 6.. How it is possible for computer to get soln at that timestep in such small no of iterns.? thanks in advance. |
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