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[solids4Foam] How to calculate drag coeff when using solids4Foam 

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July 9, 2019, 05:34 
How to calculate drag coeff when using solids4Foam

#1 
Senior Member
Ali Shayegh
Join Date: Oct 2015
Posts: 129
Rep Power: 9 
The question is: How to calculate drag coeff when using solids4Foam on foamextend 4.0? OR
Why execFlowFunctionObjects doesn't recognize regions in an FSI problem? I went thru these steps: 1 solving: Code:
user@linux$ solids4Foam Code:
forceCoeffs1 { type forceCoeffs; region fluid; libs ("libforces.so"); outputControl timeStep; outputInterval 1; patches (interface); pName p; UName U; rhoName rhoInf; log true; rhoInf 1000; CofR (0.5 0.1 0); dragDir (1 0.0 0); magUInf .2; lRef .2; Aref .04; } Code:
user@linux$ execFlowFunctionObjects Code:
Create time Create mesh for time = 0 > FOAM FATAL ERROR: Cannot find file "points" in directory "constant/polyMesh" From function Time::findInstance(const fileName&, const word&, const IOobject::readOption) in file db/Time/findInstance.C at line 148. FOAM exiting Why execFlowFunctionObjects doesn't recognize regions in an FSI problem? regards Ali 

July 9, 2019, 19:27 

#2 
Retired Super Moderator
Bruno Santos
Join Date: Mar 2009
Location: Lisbon, Portugal
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Quick answer: execFlowFunctionObjects was designed as a simply function objects execution application. It assumes that you used simpleFoam, pisoFoam or some other fluid flow solver.
Mmm... now that I think about it... inside which folder are you running that command?
__________________


July 11, 2019, 13:23 

#3  
Senior Member
Ali Shayegh
Join Date: Oct 2015
Posts: 129
Rep Power: 9 
Quote:


August 8, 2019, 05:58 

#4 
Super Moderator
Philip Cardiff
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 1,078
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Hi Ali,
The function objects should work correctly when the solids4foam solver is running. I do not have experience with execFlowFunctionObjects but possibly it does not work as expected when there are regions. So one solution is to run your simulation again with the function objects included. Philip 

September 23, 2019, 07:24 
Access to solids4foam solver!!

#5 
New Member
Hamed
Join Date: Dec 2013
Location: Istanbul
Posts: 16
Rep Power: 11 
Does anyone know how can i access to the solids4Foam solver ?


September 23, 2019, 15:20 

#7 
New Member
Hamed
Join Date: Dec 2013
Location: Istanbul
Posts: 16
Rep Power: 11 
Thank you Ali,
Dr Philip was very supportive in this field, 

October 25, 2019, 09:20 
solids4Foam for neoHookeanElastic model

#8 
New Member
Hamed
Join Date: Dec 2013
Location: Istanbul
Posts: 16
Rep Power: 11 
I am trying to use neoHookeanElastic model for FSI case of blood flow and living tissues interaction.
The FSI case consists of hyperelastic Venous valves inside a blood vessel which demands the poisson`s ratio ~0.49 and Young M ~ 2e6. The problem, however, is that for poisson`s ratio > 0.49, the solid part needs a very small time step (~1e6) with many FSI iteration numbers(~3540 iterations), and for higher time steps I got the following error : From function void Foam::neoHookeanElastic::correct(surfaceSymmTensor Field& sigma) in filematerialModels/mechanicalModel/mechanicalLaws/nonLinearGeometryLaws/neoHookeanElastic/neoHookeanElastic.C at line 401Material linearity enforced for stability! mesh and geometry are attached, thanks. 

October 25, 2019, 12:44 

#9  
Senior Member
Ali Shayegh
Join Date: Oct 2015
Posts: 129
Rep Power: 9 
Quote:
Are you sure that it is an error? Isn't it only a warning? Try these steps and see what happens:
Ali 

October 26, 2019, 11:14 

#10 
Super Moderator
Philip Cardiff
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 1,078
Rep Power: 33 
Hi Hamed,
Generally, the displacementbased approach taken by most of the solid models becomes very inefficient for large (>0.49) values of Poisson's ratio. Instead, a pressuredisplacement approach may work better e.g. see Tukovic et al presentation at the OpenFOAM Workshop in Duisburg. It may be sufficient for your work to assume a lower value. Philip 

November 3, 2019, 12:47 

#11 
New Member
Hamed
Join Date: Dec 2013
Location: Istanbul
Posts: 16
Rep Power: 11 
Hi Dr. Philip and Mr Ali;
Considering my case (FSI on Venous valves interaction with blood flow), I thought the problem was more about the wrong Poisson`s ratio and Young`s Modulus, but after trying many different values for mechanical properties, I have the same deviation around the interfaces even if I use a very fine mesh. I just made a few clarifying pictures to give you a better understanding of the problem. I would like to share my log file as well. I would also like to share my case in a private email. Thanks again for your kind supports.  Hamed Code:
Time = 0.01017 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (3.15809e06 1.50563e06 0.000304074) Total force (solid) = (3.15261e06 1.55435e06 0.000303831) Evolving solid solver Corr 0, relative residual = 1 Corr 176, relative residual = 0 PCG: Solving for D, Initial residual = 0.00892703, Final residual = 9.71689e10, No outer iterations = 176 Max relative residual = 1, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 1 Alternative fsi residual: 0.00905615 Time = 0.01017, iteration: 1 Modes before cleanup : 2, modes after cleanup : 0 Current fsi underrelaxation factor: 0.4 Maximal accumulated displacement of interface points: 0.0425372 GAMG: Solving for cellMotionUx, Initial residual = 0.222616, Final residual = 4.21496e07, No Iterations 5 GAMG: Solving for cellMotionUy, Initial residual = 0.270774, Final residual = 4.8607e07, No Iterations 5 GAMG: Solving for cellMotionUz, Initial residual = 0.264161, Final residual = 5.66204e07, No Iterations 4 GAMG: Solving for cellMotionUx, Initial residual = 0.000258033, Final residual = 4.30003e07, No Iterations 4 GAMG: Solving for cellMotionUy, Initial residual = 0.000296835, Final residual = 6.00212e07, No Iterations 3 GAMG: Solving for cellMotionUz, Initial residual = 0.000198566, Final residual = 6.33282e07, No Iterations 3 Evolving fluid model: pimpleFluid Courant Number mean: 9.5329e06 max: 0.0108989 velocity magnitude: 0.0104209 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 0.00371237, Final residual = 3.04198e09, No Iterations 3 DILUPBiCG: Solving for Uy, Initial residual = 0.00618749, Final residual = 1.04728e08, No Iterations 3 DILUPBiCG: Solving for Uz, Initial residual = 0.000905929, Final residual = 4.20485e08, No Iterations 2 DILUPBiCG: Solving for omega, Initial residual = 0.818183, Final residual = 2.64753e19, No Iterations 1 bounding omega, min: 9.23974e+15 max: 3.28545e+24 average: 1.19418e+18 DILUPBiCG: Solving for k, Initial residual = 0.00460888, Final residual = 5.78919e17, No Iterations 1 bounding k, min: 0.000151413 max: 0.015 average: 5.93991e06 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 9.75781e05, Final residual = 5.98661e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.000527519, Final residual = 1.15841e09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 2.24534e05, Final residual = 9.54317e09, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818183, Final residual = 3.29049e19, No Iterations 1 bounding omega, min: 2.72772e+23 max: 3.28545e+23 average: 3.25659e+16 DILUPBiCG: Solving for k, Initial residual = 0.000695647, Final residual = 1.98929e15, No Iterations 1 bounding k, min: 0.00010531 max: 0.015 average: 5.68596e06 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 4.75273e06, Final residual = 6.29318e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 4.45566e05, Final residual = 2.31057e08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 4.86859e07, Final residual = 6.83051e10, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.80484, Final residual = 3.6083e14, No Iterations 1 bounding omega, min: 2.72756e+23 max: 3.4008e+28 average: 4.77861e+22 DILUPBiCG: Solving for k, Initial residual = 0.00500811, Final residual = 9.96427e19, No Iterations 1 bounding k, min: 0.000209318 max: 0.015 average: 5.55772e06 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (1.98948e05 7.8638e06 0.000362569) Total force (solid) = (1.9937e05 7.83634e06 0.000362261) Evolving solid solver Corr 0, relative residual = 0.00919203 Corr 205, relative residual = 0 PCG: Solving for D, Initial residual = 1.87231e05, Final residual = 9.35021e10, No outer iterations = 205 Max relative residual = 0.00919203, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.583811 Alternative fsi residual: 0.00528709 Time = 0.01017, iteration: 2 Current fsi underrelaxation factor: 0.4 Maximal accumulated displacement of interface points: 0.0210691 GAMG: Solving for cellMotionUx, Initial residual = 0.315873, Final residual = 4.74294e07, No Iterations 5 GAMG: Solving for cellMotionUy, Initial residual = 0.270807, Final residual = 5.04984e07, No Iterations 5 GAMG: Solving for cellMotionUz, Initial residual = 0.354676, Final residual = 6.70532e07, No Iterations 4 GAMG: Solving for cellMotionUx, Initial residual = 0.000507906, Final residual = 8.95989e07, No Iterations 4 GAMG: Solving for cellMotionUy, Initial residual = 0.000569547, Final residual = 9.80743e07, No Iterations 3 GAMG: Solving for cellMotionUz, Initial residual = 0.000391171, Final residual = 4.48252e07, No Iterations 4 Evolving fluid model: pimpleFluid Courant Number mean: 4.31343e05 max: 0.0413164 velocity magnitude: 0.0435732 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 0.00158777, Final residual = 4.76985e09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00285384, Final residual = 7.03318e09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.000370663, Final residual = 1.23296e09, No Iterations 2 DILUPBiCG: Solving for omega, Initial residual = 0.818186, Final residual = 4.27636e17, No Iterations 1 bounding omega, min: 4.08304e+21 max: 1.01271e+31 average: 3.65249e+24 DILUPBiCG: Solving for k, Initial residual = 0.00586598, Final residual = 1.50905e19, No Iterations 1 bounding k, min: 8.97979e05 max: 0.015 average: 5.56469e06 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 8.59655e05, Final residual = 3.79946e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00022598, Final residual = 3.3595e10, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 1.53249e05, Final residual = 5.1753e09, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 5.44098e18, No Iterations 1 bounding omega, min: 3.61419e+21 max: 1.57421e+32 average: 4.37714e+25 DILUPBiCG: Solving for k, Initial residual = 0.0103825, Final residual = 5.63978e19, No Iterations 1 bounding k, min: 0.000190138 max: 0.015 average: 5.64058e06 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 1.67418e06, Final residual = 2.62571e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 1.59293e05, Final residual = 1.18784e08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 1.81971e07, Final residual = 1.48228e10, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 3.2336e24, No Iterations 1 bounding omega, min: 6.09275e+19 max: 1.57421e+31 average: 4.37718e+24 DILUPBiCG: Solving for k, Initial residual = 0.0010865, Final residual = 1.08661e20, No Iterations 1 bounding k, min: 8.54083e05 max: 0.015 average: 5.72519e06 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (1.15638e05 6.02827e06 0.000108811) Total force (solid) = (1.15939e05 6.02873e06 0.000108703) Evolving solid solver Corr 0, relative residual = 0.00322152 Corr 181, relative residual = 0 PCG: Solving for D, Initial residual = 7.02616e06, Final residual = 9.29248e10, No outer iterations = 181 Max relative residual = 0.00322152, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.355936 Alternative fsi residual: 0.00322341 Time = 0.01017, iteration: 3 Current fsi underrelaxation factor: 0.4 Maximal accumulated displacement of interface points: 0.0140569 GAMG: Solving for cellMotionUx, Initial residual = 0.216827, Final residual = 4.26478e07, No Iterations 5 GAMG: Solving for cellMotionUy, Initial residual = 0.233153, Final residual = 4.05695e07, No Iterations 5 GAMG: Solving for cellMotionUz, Initial residual = 0.262137, Final residual = 6.55199e07, No Iterations 4 GAMG: Solving for cellMotionUx, Initial residual = 0.00039729, Final residual = 6.83797e07, No Iterations 4 GAMG: Solving for cellMotionUy, Initial residual = 0.000435475, Final residual = 9.13487e07, No Iterations 3 GAMG: Solving for cellMotionUz, Initial residual = 0.000298678, Final residual = 9.80874e07, No Iterations 3 Evolving fluid model: pimpleFluid Courant Number mean: 6.52255e05 max: 0.0624469 velocity magnitude: 0.0644917 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 0.00102315, Final residual = 3.06738e09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00181026, Final residual = 4.56335e09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.000236891, Final residual = 8.55743e10, No Iterations 2 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 5.52221e21, No Iterations 1 bounding omega, min: 2.11844e+19 max: 1.57421e+30 average: 4.37749e+23 DILUPBiCG: Solving for k, Initial residual = 0.000107267, Final residual = 7.97726e21, No Iterations 1 bounding k, min: 0.000184072 max: 0.015 average: 5.79673e06 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 6.79402e05, Final residual = 2.47819e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.000167144, Final residual = 7.40024e08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 1.62238e05, Final residual = 5.02729e09, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 2.56549e22, No Iterations 1 bounding omega, min: 7.13393e+16 max: 1.57421e+29 average: 4.37756e+22 DILUPBiCG: Solving for k, Initial residual = 1.05613e05, Final residual = 5.23528e19, No Iterations 1 bounding k, min: 8.35123e05 max: 0.015 average: 5.85367e06 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 1.46828e06, Final residual = 1.7557e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 1.04925e05, Final residual = 8.30899e09, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 1.54619e07, Final residual = 1.43036e10, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 1.9311e25, No Iterations 1 bounding omega, min: 1.12498e+17 max: 1.57421e+28 average: 4.37757e+21 DILUPBiCG: Solving for k, Initial residual = 1.06261e06, Final residual = 1.94168e19, No Iterations 1 bounding k, min: 0.000181998 max: 0.015 average: 5.85814e06 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (6.03001e06 4.56216e06 5.01522e05) Total force (solid) = (6.05143e06 4.58066e06 5.01309e05) Evolving solid solver Corr 0, relative residual = 0.00210744 Corr 165, relative residual = 0 PCG: Solving for D, Initial residual = 4.53395e06, Final residual = 9.37221e10, No outer iterations = 165 Max relative residual = 0.00210744, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.21737 Alternative fsi residual: 0.00196853 Time = 0.01017, iteration: 4 Maximal accumulated displacement of interface points: 0.0287208 GAMG: Solving for cellMotionUx, Initial residual = 0.314755, Final residual = 4.90975e07, No Iterations 5 GAMG: Solving for cellMotionUy, Initial residual = 0.241241, Final residual = 4.9491e07, No Iterations 5 GAMG: Solving for cellMotionUz, Initial residual = 0.311435, Final residual = 6.78914e07, No Iterations 4 GAMG: Solving for cellMotionUx, Initial residual = 0.0002758, Final residual = 4.3074e07, No Iterations 4 GAMG: Solving for cellMotionUy, Initial residual = 0.000364454, Final residual = 5.55956e07, No Iterations 3 GAMG: Solving for cellMotionUz, Initial residual = 0.000200587, Final residual = 5.72831e07, No Iterations 3 Evolving fluid model: pimpleFluid Courant Number mean: 9.72781e05 max: 0.10969 velocity magnitude: 0.103467 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 0.0016107, Final residual = 5.23428e09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00291538, Final residual = 7.58568e09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.000372498, Final residual = 1.40193e09, No Iterations 2 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 1.08359e20, No Iterations 1 bounding omega, min: 1.1239e+17 max: 1.57421e+27 average: 4.37759e+20 DILUPBiCG: Solving for k, Initial residual = 1.24894e07, Final residual = 4.15435e19, No Iterations 1 bounding k, min: 8.22965e05 max: 0.015 average: 5.85003e06 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 8.99254e05, Final residual = 3.57822e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00025004, Final residual = 3.48847e10, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 2.16671e05, Final residual = 7.66342e09, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 4.82041e22, No Iterations 1 bounding omega, min: 5.78925e+19 max: 1.57421e+26 average: 4.37772e+19 DILUPBiCG: Solving for k, Initial residual = 3.04347e07, Final residual = 4.40905e19, No Iterations 1 bounding k, min: 0.000181325 max: 0.015 average: 5.84395e06 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 2.12102e06, Final residual = 2.63592e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 1.45785e05, Final residual = 1.23879e08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 2.14644e07, Final residual = 3.48884e10, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 0.818182, Final residual = 6.59323e24, No Iterations 1 bounding omega, min: 8.06657e+18 max: 1.57421e+25 average: 8.07092e+18 DILUPBiCG: Solving for k, Initial residual = 0.000808425, Final residual = 1.79874e17, No Iterations 1 bounding k, min: 8.15315e05 max: 0.015 average: 5.79382e06 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (3.08443e06 9.89652e07 0.000301391) Total force (solid) = (3.07871e06 1.03661e06 0.000301147) Evolving solid solver Corr 0, relative residual = 0.0040934 Corr 181, relative residual = 0 PCG: Solving for D, Initial residual = 7.08595e06, Final residual = 9.98638e10, No outer iterations = 181 Max relative residual = 0.0040934, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.000747883 Alternative fsi residual: 6.77294e06 ExecutionTime = 114663 s ClockTime = 114673 s forces output: forces(pressure, viscous)((0 0 0) (2.92363e07 9.41523e08 2.84259e05)) moment(pressure, viscous)((0 0 0) (2.8342e06 1.40024e05 1.36377e08)) Time = 0.01018 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (3.08443e06 9.89652e07 0.000301391) Total force (solid) = (3.07871e06 1.03661e06 0.000301147) Evolving solid solver Corr 0, relative residual = 1 Corr 178, relative residual = 0 PCG: Solving for D, Initial residual = 0.008752, Final residual = 9.17236e10, No outer iterations = 178 Max relative residual = 1, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 1 Alternative fsi residual: 0.00907011 

November 4, 2019, 12:09 

#12 
Super Moderator
Philip Cardiff
Join Date: Mar 2009
Location: Dublin, Ireland
Posts: 1,078
Rep Power: 33 
Hi Hamed,
Does the gap become smaller as the FSI tolerance is tightened? Or alternatively, does it become larger as the FSI tolerance is loosened? It looks like your mesh is conformal; is that true? In that case, you can use the directMap approached instead of the GGI; you could also try RBF. Both are implemented in solids4foam. Philip 

November 5, 2019, 14:33 

#13  
Senior Member
Ali Shayegh
Join Date: Oct 2015
Posts: 129
Rep Power: 9 
Quote:
As I see infinity values in your omega field, it seems that your fluid flow is not solved properly. What do you think? I suggest trying this simulation to solve only fluid and not interaction first. You can do this by turning off fsi in : Code:
constant/fsiProperties 

November 6, 2019, 11:26 

#14 
New Member
Hamed
Join Date: Dec 2013
Location: Istanbul
Posts: 16
Rep Power: 11 
Dear Ali,
First, you’re right. The solver is getting problem with the omega field, that’s why the bounding term came in. This problem can be solved if I use fixed value velocity through inlet instead of being required to use time series velocity. Second, following your suggestions, I just reduce the Tolerance for the FSI loop within each timestep from 1e6 to 1e3, and the solver takes a few quick iterations for convergence, and that’s much better right now. But, the deviation in between the interfaces is getting larger, and I hope that would be its maximum value. Dear Philip, If you mean the interfaces deviation gap, the time series velocity profile seems to be related problem as well. I don’t have that much deviation gap when I use fixed value velocity at the inlet patch. I feel that the solver doesn’t work fine with some time series velocity BC. Regarding the Method for transferring information between the interfaces, direct map approach doesn’t work well even if use a very fined conformal mesh created by ICEM CFD block structured approach. Plus, RBF works much better than GGI. In sum, as I mentioned before, the procedure sounds to be much better now, but the deviation gap is widening over time, and I think this is becuase the FSI tolerance (1e3) is too much. Lower FSI tolerance (1e6), however, demands many iterations. The other confusing point is that the current time step is 1e5 with 0.0034 Co number, but if I take it 23 times bigger, the solver simply crashes. Furthermore, the inlet patch is far from the FSI interface at the beginning, and it should take some time for flow field to reach there. But, the interface starts to move short after the start time. Regards Hamed Code:
Time = 0.00718 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (2.33377e08 3.01451e07 1.21318e05) Total force (solid) = (2.15632e08 3.02419e07 1.21189e05) Evolving solid solver Corr 0, relative residual = 1 Corr 242, relative residual = 0 PCG: Solving for D, Initial residual = 0.00284558, Final residual = 9.3859e10, No outer iterations = 242 Max relative residual = 1, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 1 Alternative fsi residual: 0.00234895 Time = 0.00718, iteration: 1 Modes before cleanup : 2, modes after cleanup : 0 Current fsi underrelaxation factor: 0.05 Maximal accumulated displacement of interface points: 4.10358e05 GAMG: Solving for cellMotionUx, Initial residual = 0.840076, Final residual = 2.39959e07, No Iterations 7 GAMG: Solving for cellMotionUy, Initial residual = 0.846326, Final residual = 8.91448e07, No Iterations 7 GAMG: Solving for cellMotionUz, Initial residual = 0.888646, Final residual = 9.87733e07, No Iterations 6 GAMG: Solving for cellMotionUx, Initial residual = 0.320706, Final residual = 7.29239e07, No Iterations 8 GAMG: Solving for cellMotionUy, Initial residual = 0.483341, Final residual = 9.35381e07, No Iterations 9 GAMG: Solving for cellMotionUz, Initial residual = 0.329802, Final residual = 5.32541e07, No Iterations 8 Evolving fluid model: pimpleFluid Courant Number mean: 1.1378e06 max: 0.0038489 velocity magnitude: 0.100049 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 0.000822067, Final residual = 2.49849e10, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.000776971, Final residual = 3.60458e09, No Iterations 2 DILUPBiCG: Solving for Uz, Initial residual = 0.000224024, Final residual = 1.25943e09, No Iterations 2 DILUPBiCG: Solving for omega, Initial residual = 1.05632e05, Final residual = 3.48389e09, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 0.000398424, Final residual = 2.46952e07, No Iterations 1 bounding k, min: 8.52414e10 max: 0.0152085 average: 0.00947244 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 1.07711e05, Final residual = 4.34146e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 1.41384e05, Final residual = 8.04891e09, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 3.48485e07, Final residual = 3.49716e10, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 1.06643e06, Final residual = 4.72058e10, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 4.08304e05, Final residual = 2.89133e08, No Iterations 1 bounding k, min: 3.43264e11 max: 0.0152085 average: 0.00947211 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 4.595e08, Final residual = 3.15598e11, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 5.08656e08, Final residual = 4.0114e11, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 3.0592e09, Final residual = 3.30954e12, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 1.0566e07, Final residual = 5.76603e11, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 4.18618e06, Final residual = 3.45449e09, No Iterations 1 bounding k, min: 8.51751e10 max: 0.0152085 average: 0.00947208 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (9.58789e09 2.0536e07 2.23259e06) Total force (solid) = (9.05041e09 2.07311e07 2.22094e06) Evolving solid solver Corr 0, relative residual = 0.00108072 Corr 177, relative residual = 0 PCG: Solving for D, Initial residual = 4.66104e06, Final residual = 9.87664e10, No outer iterations = 177 Max relative residual = 0.00108072, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.946871 Alternative fsi residual: 0.00222415 Time = 0.00718, iteration: 2 Current fsi underrelaxation factor: 0.05 Maximal accumulated displacement of interface points: 3.88777e05 GAMG: Solving for cellMotionUx, Initial residual = 0.0600702, Final residual = 3.16851e07, No Iterations 7 GAMG: Solving for cellMotionUy, Initial residual = 0.0923394, Final residual = 7.79415e07, No Iterations 8 GAMG: Solving for cellMotionUz, Initial residual = 0.0666684, Final residual = 4.59348e07, No Iterations 7 GAMG: Solving for cellMotionUx, Initial residual = 0.0131503, Final residual = 4.48109e07, No Iterations 6 GAMG: Solving for cellMotionUy, Initial residual = 0.0288351, Final residual = 7.12569e07, No Iterations 7 GAMG: Solving for cellMotionUz, Initial residual = 0.0169817, Final residual = 7.17113e07, No Iterations 6 Evolving fluid model: pimpleFluid Courant Number mean: 9.25785e07 max: 0.0038489 velocity magnitude: 0.100049 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 8.36956e06, Final residual = 2.43038e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 7.197e06, Final residual = 3.83537e09, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 9.13025e08, Final residual = 7.72385e11, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 3.10613e07, Final residual = 1.17103e10, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 4.74007e07, Final residual = 3.76998e10, No Iterations 1 bounding k, min: 2.57545e12 max: 0.0152085 average: 0.00947207 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 1.29491e06, Final residual = 6.6442e10, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 1.76408e06, Final residual = 9.90313e10, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 3.96689e08, Final residual = 4.08151e11, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 3.33405e08, Final residual = 1.82678e11, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 4.8677e08, Final residual = 5.0997e11, No Iterations 1 bounding k, min: 8.52066e10 max: 0.0152085 average: 0.00947207 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 2.60354e09, Final residual = 3.21151e12, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 2.9883e09, Final residual = 3.31592e12, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 7.88369e11, Final residual = 7.39832e14, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 3.23573e09, Final residual = 2.22854e12, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 5.07204e09, Final residual = 6.06171e12, No Iterations 1 bounding k, min: 5.67284e12 max: 0.0152085 average: 0.00947207 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (6.91648e09 1.89368e07 2.83362e06) Total force (solid) = (6.47144e09 1.91187e07 2.82192e06) Evolving solid solver Corr 0, relative residual = 6.13304e05 Corr 83, relative residual = 0 PCG: Solving for D, Initial residual = 2.70202e07, Final residual = 9.67325e10, No outer iterations = 83 Max relative residual = 6.13304e05, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.899692 Alternative fsi residual: 0.00211333 Time = 0.00718, iteration: 3 Current fsi underrelaxation factor: 0.05 Maximal accumulated displacement of interface points: 3.69388e05 GAMG: Solving for cellMotionUx, Initial residual = 0.0275252, Final residual = 7.98234e07, No Iterations 5 GAMG: Solving for cellMotionUy, Initial residual = 0.0292615, Final residual = 7.50964e07, No Iterations 6 GAMG: Solving for cellMotionUz, Initial residual = 0.0303498, Final residual = 4.56572e07, No Iterations 6 GAMG: Solving for cellMotionUx, Initial residual = 0.0027185, Final residual = 4.0568e07, No Iterations 5 GAMG: Solving for cellMotionUy, Initial residual = 0.00533021, Final residual = 4.11815e07, No Iterations 6 GAMG: Solving for cellMotionUz, Initial residual = 0.00351797, Final residual = 5.2661e07, No Iterations 5 Evolving fluid model: pimpleFluid Courant Number mean: 7.32008e07 max: 0.0038489 velocity magnitude: 0.100049 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 8.14705e06, Final residual = 2.29806e09, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 6.91261e06, Final residual = 3.6221e09, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 8.75404e08, Final residual = 7.03357e11, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 2.81286e07, Final residual = 1.2101e10, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 6.49217e08, Final residual = 4.47831e11, No Iterations 1 bounding k, min: 7.58949e10 max: 0.0152085 average: 0.00947207 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 1.367e06, Final residual = 5.53742e10, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 1.57508e06, Final residual = 9.00186e10, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 3.50923e08, Final residual = 3.10754e11, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 2.99862e08, Final residual = 1.82564e11, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 6.73838e09, Final residual = 5.65891e12, No Iterations 1 bounding k, min: 8.51795e10 max: 0.0152085 average: 0.00947207 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 2.16595e09, Final residual = 2.18187e12, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 2.64342e09, Final residual = 3.20919e12, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 5.99663e11, Final residual = 1.36567e13, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 2.9135e09, Final residual = 2.17967e12, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 6.94569e10, Final residual = 6.58861e13, No Iterations 1 bounding k, min: 7.58995e10 max: 0.0152085 average: 0.00947207 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (3.96849e09 1.69376e07 3.41162e06) Total force (solid) = (3.61189e09 1.71066e07 3.3999e06) Evolving solid solver Corr 0, relative residual = 6.18627e05 Corr 86, relative residual = 0 PCG: Solving for D, Initial residual = 2.65482e07, Final residual = 9.24092e10, No outer iterations = 86 Max relative residual = 6.18627e05, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.854873 Alternative fsi residual: 0.00200806 Time = 0.00718, iteration: 4 Maximal accumulated displacement of interface points: 0.000703515 GAMG: Solving for cellMotionUx, Initial residual = 0.899139, Final residual = 3.14282e07, No Iterations 7 GAMG: Solving for cellMotionUy, Initial residual = 0.899561, Final residual = 7.76862e07, No Iterations 7 GAMG: Solving for cellMotionUz, Initial residual = 0.908687, Final residual = 2.81354e07, No Iterations 7 GAMG: Solving for cellMotionUx, Initial residual = 0.0274633, Final residual = 8.09574e07, No Iterations 6 GAMG: Solving for cellMotionUy, Initial residual = 0.0409861, Final residual = 6.12213e07, No Iterations 7 GAMG: Solving for cellMotionUz, Initial residual = 0.026483, Final residual = 4.1743e07, No Iterations 6 Evolving fluid model: pimpleFluid Courant Number mean: 3.48986e06 max: 0.0038489 velocity magnitude: 0.100049 PIMPLE: iteration 1 DILUPBiCG: Solving for Ux, Initial residual = 0.000164904, Final residual = 4.44584e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.000137998, Final residual = 6.90704e08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 1.68687e06, Final residual = 1.2523e09, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 2.7701e06, Final residual = 8.76416e10, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 7.9778e07, Final residual = 5.9646e10, No Iterations 1 bounding k, min: 5.29395e12 max: 0.0152085 average: 0.00947207 PIMPLE: iteration 2 DILUPBiCG: Solving for Ux, Initial residual = 4.63699e05, Final residual = 1.05237e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 3.83718e05, Final residual = 1.58858e08, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 5.43873e07, Final residual = 2.87303e10, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 2.97631e07, Final residual = 1.42784e10, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 8.22545e08, Final residual = 6.35442e11, No Iterations 1 bounding k, min: 8.51511e10 max: 0.0152085 average: 0.00947207 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 3.5925e08, Final residual = 2.57546e11, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 4.12395e08, Final residual = 3.52182e11, No Iterations 1 DILUPBiCG: Solving for Uz, Initial residual = 6.36586e10, Final residual = 4.37736e12, No Iterations 1 DILUPBiCG: Solving for omega, Initial residual = 2.89809e08, Final residual = 1.54184e11, No Iterations 1 DILUPBiCG: Solving for k, Initial residual = 8.56864e09, Final residual = 7.18223e12, No Iterations 1 bounding k, min: 6.90639e13 max: 0.0152085 average: 0.00947207 Setting traction on solid patch Interpolating from fluid to solid using GGI/AMI interpolation Total force (fluid) = (2.53231e08 2.77636e07 1.28999e05) Total force (solid) = (2.35382e08 2.78443e07 1.28879e05) Evolving solid solver Corr 0, relative residual = 0.00101833 Corr 175, relative residual = 0 PCG: Solving for D, Initial residual = 4.27465e06, Final residual = 9.68254e10, No outer iterations = 175 Max relative residual = 0.00101833, Relative residual = 0, enforceLinear = false Interpolating from solid to fluid using GGI/AMI interpolation Interpolating from solid to fluid using GGI/AMI interpolation Current fsi relative residual norm: 0.000862285 Alternative fsi residual: 2.02547e06 ExecutionTime = 10730.1 s ClockTime = 10731 s forces output: forces(pressure, viscous)((0 0 0) (2.39268e09 2.61921e08 1.21742e06)) moment(pressure, viscous)((0 0 0) (1.20252e07 5.99465e07 1.26537e08)) 

November 7, 2019, 08:40 

#15  
Senior Member
Ali Shayegh
Join Date: Oct 2015
Posts: 129
Rep Power: 9 
Hi Hamed,
Are you sure that it is not only a visualization problem? (Read this post.) Quote:
Quote:
Regards Ali 

November 7, 2019, 12:50 

#16  
Senior Member
Daniel
Join Date: Mar 2013
Location: Noshahr, Iran
Posts: 348
Rep Power: 20 
Quote:
Does your case run properly when you solve for the fluid only case? How this so called time dependent velocity is formulated for inlet? Is the velocity variation smooth enough to prevent velocity jump during simulation? If you are not sure the fluid part is producing stable and accurate solution, then heading directly to the fsi case can drastically increase time to diagnose the actual reason behind this behavior. From past I recall that one should use combined pulsatile pressure/velocity boundary condition at inlet and outlet to obtain physically correct results. Quote:
You can do this when you are trying to determine the cause of instabilities but set it back to a tighter value when you are ready to run the final case. As you have already observed, loosening the fsi tolerance may provide faster simulation but it also results in large gap between interfaces and your simulation will probably crash do the accumulation of errors. Specially in these cases as the simulation is strongly coupled with a low elastic modulus and density ratio ~ O(1). Quote:
Quote:
One more thing, try setting pimple outer loop correction to 1 and see what happens. Quote:
What is the forces values being transferred to solid side at the beginning of the simulation before solving the fluid region? I strongly suggest providing better initial condition for fluid region before starting a coupled solution. If the velocity is pulsatile then run the fluid region for a single cycle before turning the coupled switch on. Finally, why I don't see pressure equation getting solved in your log file? It is just missing from the log or you are some how managed not to solve for it? Regards, D. Khazaei 

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