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problem with mesh after some timesteps in icoFsiElasticNonLinULSolidFoam solver 

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January 17, 2019, 09:56 
problem with mesh after some timesteps in icoFsiElasticNonLinULSolidFoam solver

#1 
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Hojatollah Gholami
Join Date: Jan 2019
Posts: 133
Rep Power: 4 
Dear
I try to solve FSI problem with two or more elastic beams in flow channel. First, I generate mesh with ansys mechanical and import to openFoamext4.0, then checkMesh and it OK. uses createPatch to merge some boundary and still mesh OK. after running after some timesteps, appear errors "Floating point exception (core dumped)". I checkMesh and found "Failed 1 mesh checks" with this statement Checking geometry... This is a 2D mesh Overall domain bounding box (0.3 0.025 0) (0.5 0.025 0.0002) Mesh (nonempty, nonwedge) directions (1 1 0) Mesh (nonempty) directions (1 1 0) Mesh (nonempty, nonwedge) dimensions 2 ***Number of edges not aligned with or perpendicular to nonempty directions: 153 Writing 306 points on nonaligned edges to set nonAlignedEdges Boundary openness (1.17707e20 7.90055e19 7.14214e19) Threshold = 1e06 OK. Max cell openness = 2.04795e16 OK. Max aspect ratio = 170.202 OK. Minumum face area = 1.29252e08. Maximum face area = 6.80809e05. Face area magnitudes OK. Min volume = 2.58504e12. Max volume = 1.36162e08. Total volume = 7.88827e06. Cell volumes OK. Mesh nonorthogonality Max: 50.0436 average: 12.3892 Threshold = 70 Nonorthogonality check OK. Face pyramids OK. Max skewness = 2.49004 OK. Failed 1 mesh checks.  Maybe it's due to dynamicMesh. My dynamicMeshDict is as: dynamicFvMesh dynamicMotionSolverFvMesh; twoDMotion yes; solver refVelocityLaplacian; diffusivity quadratic inverseDistance 2(elastic fix); nNonOrthogonalCorrectors 2; leastSquaresVolPoint yes;  I can't recognize why the error appear? Anyone Can help me? thanks a lot. 

January 17, 2019, 11:02 

#2 
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anonymous
Join Date: Jan 2016
Posts: 405
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Hi!
I'm not so familiar with icoFsiElasticNonLinULSolidFoam, but based on your description it is seems like you have a 2D mesh, and i think the structure is moving out of the plane. ("***Number of edges not aligned with or perpendicular to nonempty directions: 153") Try to constrain it in order to stay in the plane. And you can visualize the bad points in paraview ("Writing 306 points on nonaligned edges to set nonAlignedEdges"), so you can check the location of the error. And try to use planeStrain to avoid the Poisson effect. (Maybe this won't be a good modelling approach for you but you can try to find the problem) 

January 18, 2019, 01:08 

#3 
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Hojatollah Gholami
Join Date: Jan 2019
Posts: 133
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Dear simrego
I use flattenMesh to fix the problem. again I run the solver, but in first time step after some iteration give error. Now the checkMesh is OK. Time = 0.0001, iteration: 5 Maximal accumulated displacement of interface points: 0.00229892 Courant Number mean: 0.00785269 max: 4.97262 velocity magnitude: 14.1465 BiCGStab: Solving for Ux, Initial residual = 0.00175064, Final residual = 1.186e07, No Iterations 3 BiCGStab: Solving for Uy, Initial residual = 0.00818076, Final residual = 7.47515e07, No Iterations 3 Floating point exception (core dumped)  is Anybody fix this error? 

January 18, 2019, 12:58 

#4 
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Hojatollah Gholami
Join Date: Jan 2019
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I change the parameters of fvscheme and the problem solved.


January 20, 2019, 23:12 

#5 
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wulonglong
Join Date: Jan 2018
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May i ask a question,
what is the difference between icoFsiElasticNonLinULSolidFoam and fsiFoam? 

January 21, 2019, 01:12 

#6 
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Hojatollah Gholami
Join Date: Jan 2019
Posts: 133
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Dear wulonglong
I thinks the two solver have the same algorithm to solve FSI problem. The only reason that I use icoFsiElasticNonLinULSolidFoam, is due to separated files in the solver. I want to modify the fluid solver to add thermal equation. In my opinion, icoFsiElasticNonLinULSolidFoam is understandable than fsiFoam and easily we can add extra equation to it. 

March 21, 2019, 07:45 
Dear Hgholami

#7 
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Could you explain the specific details?Here i need the parameters to continue the case,once i run the case and it stopped without other reminds but "Floating point exception (core dumped)".
Thank you in advance. 

March 21, 2019, 08:10 
Dear Nexfast

#8  
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Quote:
Also, i used Openfoam4.1 and i run the same case.But i can't see the solid to swing up and down,so i change the E of the solid,but it went wrong ,and give the information "Floating point exception (core dumped)". Can you explain the ways to tun the case in detail?I have spent much time in this problem,thank you in advance. 

March 21, 2019, 09:13 

#9  
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Hojatollah Gholami
Join Date: Jan 2019
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check this first fvscheme
Quote:
Quote:
Quote:


March 21, 2019, 22:56 
Dear Hgholami

#10  
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Quote:
Except this,did you change some other parameters,such as the E of the solid (compare to the basic case,because in another thread,you also saied you use some tools and use the solver of fsiFoam,then get the result.) Thank you in advance. 

March 22, 2019, 00:41 

#11 
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Hojatollah Gholami
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which solver do you want to use? fsiFoam or icoFsiElasticNonLinULSolidFoam


March 22, 2019, 04:11 
Dear Hgholami

#12 
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March 22, 2019, 05:37 

#13  
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Hojatollah Gholami
Join Date: Jan 2019
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you can also use fsiFoam by installing FSI toolkits.
my configuration in icoFsiElasticNonLinULSolidFoam was Quote:


March 22, 2019, 06:34 
Dear Hgholami

#14 
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February 2, 2020, 10:53 
problem with mesh after some timesteps in icoFsiElasticNonLinULSolidFoam solver

#15 
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DouglasFreds
Join Date: Jan 2020
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Hi, Looks ok in my current ElmerGUI version. Maybe you have quite on old ElmerGUI? You could also try to translate it manually ElmerGrid 14 2 mymesh.msh autoclean and the open the mesh in ElmerGUI. Peter


Tags 
dynamicmeshdict, fsi, fsi 2way 
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