Problem with complex eigenValues

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 July 13, 2015, 10:11 Problem with complex eigenValues #1 Member   Join Date: Dec 2014 Posts: 50 Rep Power: 4 Hey, Using the icoFsiElasticNonLinULSolidFoam solver to simulate beam deformation due to some kind of fluid (resin) I get the following problem with complex eigenValues. Code: ```Create time Create dynamic mesh for time = 0 Selecting dynamicFvMesh dynamicMotionSolverFvMesh Selecting motion solver: laplace Selecting motion diffusivity: quadratic Reading transportProperties Reading field p Reading field U Reading/calculating face flux field phi Reading incremental displacement field DU Patch consoleSolid Traction boundary field: DU nonLinear set to updated Lagrangian Reading incremental displacement field DV Reading accumulated velocity field V Reading accumulated stress field sigma Reading incremental stress field DSigma Selecting rheology model linearElastic Creating constitutive model Reading coupling properties Create fluid-to-solid and solid-to-fluid interpolators Check fluid-to-solid and solid-to-fluid interpolators Fluid-to-solid face interpolation error: 0.010148376 Solid-to-fluid face interpolation error: 0.01019123 Starting time loop Time = 0.001 Selecting coupling scheme Aitken Time = 0.001, iteration: 1 Current fsi under-relaxation factor: 0.01 Maximal accumulated displacement of interface points: 0 Courant Number mean: 0 max: 0 velocity magnitude: 0 DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 8.3132673e-07, No Iterations 18 DILUPBiCG: Solving for Uy, Initial residual = 0, Final residual = 0, No Iterations 0 DILUPBiCG: Solving for Uz, Initial residual = 0, Final residual = 0, No Iterations 0 GAMG: Solving for p, Initial residual = 1, Final residual = 8.4510406e-07, No Iterations 31 GAMG: Solving for p, Initial residual = 0.11197892, Final residual = 4.9492681e-07, No Iterations 23 GAMG: Solving for p, Initial residual = 0.019307684, Final residual = 5.7220616e-07, No Iterations 19 GAMG: Solving for p, Initial residual = 0.0051776203, Final residual = 8.4609257e-07, No Iterations 13 GAMG: Solving for p, Initial residual = 0.0018300923, Final residual = 9.1210219e-07, No Iterations 9 GAMG: Solving for p, Initial residual = 0.00066812399, Final residual = 6.8161564e-07, No Iterations 7 time step continuity errors : sum local = 1.2555142e-08, global = -2.3714846e-10, cumulative = -2.3714846e-10 GAMG: Solving for p, Initial residual = 0.53146611, Final residual = 5.978844e-07, No Iterations 29 GAMG: Solving for p, Initial residual = 0.20182154, Final residual = 9.9028612e-07, No Iterations 24 GAMG: Solving for p, Initial residual = 0.042800682, Final residual = 5.2895856e-07, No Iterations 21 GAMG: Solving for p, Initial residual = 0.011775962, Final residual = 9.6208771e-07, No Iterations 15 GAMG: Solving for p, Initial residual = 0.0041584696, Final residual = 4.5080195e-07, No Iterations 13 GAMG: Solving for p, Initial residual = 0.0015133582, Final residual = 7.2392118e-07, No Iterations 8 time step continuity errors : sum local = 5.5095195e-09, global = 2.1325662e-10, cumulative = -2.3891839e-11 GAMG: Solving for p, Initial residual = 0.29927741, Final residual = 9.4244826e-07, No Iterations 24 GAMG: Solving for p, Initial residual = 0.012474404, Final residual = 9.8173954e-07, No Iterations 16 GAMG: Solving for p, Initial residual = 0.0021021264, Final residual = 9.130113e-07, No Iterations 10 GAMG: Solving for p, Initial residual = 0.00060303569, Final residual = 7.4261747e-07, No Iterations 7 GAMG: Solving for p, Initial residual = 0.00022272133, Final residual = 5.699134e-07, No Iterations 6 GAMG: Solving for p, Initial residual = 8.4422059e-05, Final residual = 4.7794747e-07, No Iterations 5 time step continuity errors : sum local = 2.4638291e-09, global = 9.6306776e-11, cumulative = 7.2414937e-11 GAMG: Solving for p, Initial residual = 0.15397893, Final residual = 4.9561848e-07, No Iterations 21 GAMG: Solving for p, Initial residual = 0.0040461499, Final residual = 8.909345e-07, No Iterations 12 GAMG: Solving for p, Initial residual = 0.00060316435, Final residual = 7.2521584e-07, No Iterations 6 GAMG: Solving for p, Initial residual = 0.00015816922, Final residual = 8.635744e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 5.5933466e-05, Final residual = 6.7512527e-07, No Iterations 4 GAMG: Solving for p, Initial residual = 2.0009206e-05, Final residual = 7.0327084e-07, No Iterations 3 time step continuity errors : sum local = 3.0437577e-09, global = 5.0514774e-11, cumulative = 1.2292971e-10 GAMG: Solving for p, Initial residual = 0.09966961, Final residual = 7.9882574e-07, No Iterations 19 GAMG: Solving for p, Initial residual = 0.0021026035, Final residual = 7.7451051e-07, No Iterations 11 GAMG: Solving for p, Initial residual = 0.0003114969, Final residual = 8.0088546e-07, No Iterations 6 GAMG: Solving for p, Initial residual = 7.9168706e-05, Final residual = 4.1457659e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 2.7196661e-05, Final residual = 4.5421346e-07, No Iterations 4 GAMG: Solving for p, Initial residual = 9.7404879e-06, Final residual = 9.6395309e-07, No Iterations 2 time step continuity errors : sum local = 3.742613e-09, global = 3.7893867e-11, cumulative = 1.6082358e-10 GAMG: Solving for p, Initial residual = 0.067709768, Final residual = 3.3787923e-07, No Iterations 19 GAMG: Solving for p, Initial residual = 0.001238497, Final residual = 6.5694878e-07, No Iterations 9 GAMG: Solving for p, Initial residual = 0.00018346641, Final residual = 9.203233e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 4.7386527e-05, Final residual = 5.6317931e-07, No Iterations 4 GAMG: Solving for p, Initial residual = 1.6343804e-05, Final residual = 6.4763955e-07, No Iterations 3 GAMG: Solving for p, Initial residual = 6.0068916e-06, Final residual = 6.3302699e-07, No Iterations 2 time step continuity errors : sum local = 2.2796623e-09, global = 4.0342121e-11, cumulative = 2.011657e-10 GAMG: Solving for p, Initial residual = 0.049479011, Final residual = 4.0133808e-07, No Iterations 19 GAMG: Solving for p, Initial residual = 0.0008968961, Final residual = 9.4596208e-07, No Iterations 8 GAMG: Solving for p, Initial residual = 0.00014130527, Final residual = 8.4796864e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 3.7615407e-05, Final residual = 4.6315112e-07, No Iterations 4 GAMG: Solving for p, Initial residual = 1.3117843e-05, Final residual = 5.2243324e-07, No Iterations 3 GAMG: Solving for p, Initial residual = 4.9612375e-06, Final residual = 5.3065942e-07, No Iterations 2 time step continuity errors : sum local = 1.8024859e-09, global = 3.4321021e-11, cumulative = 2.3548672e-10 GAMG: Solving for p, Initial residual = 0.037470098, Final residual = 9.1049378e-07, No Iterations 17 GAMG: Solving for p, Initial residual = 0.00062369277, Final residual = 7.6589462e-07, No Iterations 7 GAMG: Solving for p, Initial residual = 9.851143e-05, Final residual = 5.9136462e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 2.55739e-05, Final residual = 7.3420652e-07, No Iterations 3 GAMG: Solving for p, Initial residual = 9.0831531e-06, Final residual = 8.9706984e-07, No Iterations 2 GAMG: Solving for p, Initial residual = 3.539342e-06, Final residual = 4.1343948e-07, No Iterations 2 time step continuity errors : sum local = 1.3410325e-09, global = 4.1947225e-11, cumulative = 2.7743395e-10 GAMG: Solving for p, Initial residual = 0.029567073, Final residual = 8.7894614e-07, No Iterations 17 GAMG: Solving for p, Initial residual = 0.00049695739, Final residual = 7.2217496e-07, No Iterations 7 GAMG: Solving for p, Initial residual = 8.0604414e-05, Final residual = 5.182067e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 2.2075999e-05, Final residual = 7.3302099e-07, No Iterations 3 GAMG: Solving for p, Initial residual = 7.8158024e-06, Final residual = 8.0647039e-07, No Iterations 2 GAMG: Solving for p, Initial residual = 3.162127e-06, Final residual = 9.8778579e-07, No Iterations 1 time step continuity errors : sum local = 3.0850137e-09, global = 3.9143509e-11, cumulative = 3.1657745e-10 GAMG: Solving for p, Initial residual = 0.02352783, Final residual = 7.2779874e-07, No Iterations 17 GAMG: Solving for p, Initial residual = 0.00037960579, Final residual = 7.6354505e-07, No Iterations 6 GAMG: Solving for p, Initial residual = 6.1634295e-05, Final residual = 4.0162528e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 1.630773e-05, Final residual = 4.8443595e-07, No Iterations 3 GAMG: Solving for p, Initial residual = 5.7762329e-06, Final residual = 5.7300479e-07, No Iterations 2 GAMG: Solving for p, Initial residual = 2.2465927e-06, Final residual = 6.8744055e-07, No Iterations 1 time step continuity errors : sum local = 2.0815317e-09, global = 3.8350853e-11, cumulative = 3.5492831e-10 Setting traction on solid patch Total traction force = (9.5242657e-11 -3.677489e-12 7.535462e-10) --> FOAM Warning : From function eigenValues(const tensor&) in file primitives/Tensor/tensor/tensor.C at line 170 complex eigenvalues detected for tensor: (-9177.5336 -1.619439e-05 0.012441039 94407.607 -82602.655 7.4239701e+08 -74434408 62320794 -5.8801867e+11) . . . . . --> FOAM Warning : From function eigenValues(const tensor&) in file primitives/Tensor/tensor/tensor.C at line 170 complex eigenvalues detected for tensor: (-5.5240793e+21 0 0 -5.9533364e+32 4.9617278e+32 -4.6815738e+36 -3.2393035e+35 2.6998181e+35 -2.5473779e+39) Floating point exception (core dumped)``` I'm using the default values of the HronTurekFsi tutorial for the icoFsiElasticNonLinULSolidFoam solver. So, I didn't change any setting for nor the fluid neither the solid domain. I already read the tensor.C file trying to understand it but I'm not that good in C++ :/ Maybe the solution for my problem is given there and I'm just incapable to get it ' Could you guys please help me? I'm stuck with this for days now Every suggestion is very welcomed

 July 14, 2015, 02:31 #2 Senior Member   Join Date: Jan 2015 Posts: 130 Rep Power: 4 I think that no one find a solution for this problem... I'm also searching for solution but without success. foam-extend is not well-supported by community.

July 20, 2015, 08:36
#3
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Join Date: Dec 2014
Posts: 50
Rep Power: 4
Quote:
 Originally Posted by Svensen I think that no one find a solution for this problem... I'm also searching for solution but without success. foam-extend is not well-supported by community.
Do you have this problem, too?

 July 21, 2015, 01:19 #4 Senior Member   Join Date: Jan 2015 Posts: 130 Rep Power: 4 Yes, I have this problem too and I don't find a solution for it... rasool_soofi likes this.

 August 3, 2015, 10:38 #5 New Member   rasool soofi nooghabi Join Date: Mar 2015 Posts: 16 Rep Power: 4 hi can you find a solution for this problem ? I have this problem, too thank you

August 4, 2015, 08:38
#6
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Join Date: Dec 2014
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Rep Power: 4
Quote:
 Originally Posted by rasool_soofi hi can you find a solution for this problem ? I have this problem, too thank you
Hey,

Yes, actually I found my problem. It was due to a false numbering of the blocks with hex ().
The User's Guide says:
Quote:
 Each block has a local coordinate system that must be right-handed. A right-handed set of axes is defined such that to an observer looking down the axis, with nearest them, the arc from a point on the axis to a point on the axis is in a clockwise sense.
I accidentally read over this part

Hope, it helps for you..

November 2, 2015, 11:18
#7
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Join Date: Dec 2014
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Svensen:
Quote:
 Yes, I have this problem too and I don't find a solution for it...
and rasool_sosfi:
Quote:
 hi can you find a solution for this problem ? I have this problem, too thank you
Do you guys still have this problem?

November 16, 2015, 02:36
#8
New Member

rasool soofi nooghabi
Join Date: Mar 2015
Posts: 16
Rep Power: 4
hi
yes ,i have this problem yet
i am using icofsinonlinulsolidfoam sover from foam-extend 3.1
when i run my case with geometry scale of 200 and time step of 0.01 i dont have this problem
but when i run my case with geometry scale of 1 and time step of 0.000001 this problem occur and stop my solution .
courant number during solution is low.

myfsi.log file
Attached Images
 fsi.jpg (114.2 KB, 14 views)

 November 17, 2015, 03:18 #9 New Member   rasool soofi nooghabi Join Date: Mar 2015 Posts: 16 Rep Power: 4 thank you harak ! my case geometery generated by gambit . what means (right handed coordinate ...) in gambit mesh ??

 November 21, 2015, 04:22 #10 Member   Join Date: Dec 2014 Posts: 50 Rep Power: 4 Hi Rasool, sorry for the late answer. However, I assume that this problem occurs at your case because you're using a third party mesh generation tool. The solver icofsinonlinulsolidfoam needs a 1:1 face match between the fluid and the solid patch. I'm pretty sure that your mesh isn't considering this fact. Try using blockMesh for your geometry I hope your geometry isn't that complicated And please let me know if this is working for you.

 November 24, 2015, 06:01 #11 Senior Member   Join Date: Jan 2015 Posts: 130 Rep Power: 4 Does anyone find a solution ?

 January 26, 2016, 02:48 #12 Senior Member   Join Date: Jan 2015 Posts: 130 Rep Power: 4 Does anyone found a solution ?

 Tags complex eigenvalues, fluid structure, fsi

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