[dewey]

Hi, I am trying to simulate cerebral aneurysm with solids4Foam. First, I am trying to simulate a straight tube (artery) with the pulsatile signal, but still without success. I don't know if the problem is my set up or the mesh, because I already tried different meshes. Could you take a look at my set up?

Time = 1e-05, iteration: 2
Current fsi under-relaxation factor: 0.005
Maximal accumulated displacement of interface points: 0.135975
GAMG: Solving for cellMotionUx, Initial residual = 1, Final residual = 2.49757e-05, No Iterations 1
GAMG: Solving for cellMotionUy, Initial residual = 1, Final residual = 2.49445e-05, No Iterations 1
GAMG: Solving for cellMotionUz, Initial residual = 1, Final residual = 0.000559924, No Iterations 1
GAMG: Solving for cellMotionUx, Initial residual = 0.000580099, Final residual = 5.1123e-07, No Iterations 2
GAMG: Solving for cellMotionUy, Initial residual = 0.000557116, Final residual = 5.33271e-07, No Iterations 2
GAMG: Solving for cellMotionUz, Initial residual = 0.0026944, Final residual = 1.24359e-06, No Iterations 3
Evolving fluid model: icoFluid
Courant Number mean: 0.00753524 max: 0.135313 velocity magnitude: 0.259254
DILUPBiCG: Solving for Ux, Initial residual = 0.781496, Final residual = 1.09359e-11, No Iterations 3
DILUPBiCG: Solving for Uy, Initial residual = 0.784925, Final residual = 1.12075e-11, No Iterations 3
DILUPBiCG: Solving for Uz, Initial residual = 0.265502, Final residual = 6.2571e-12, No Iterations 3
GAMG: Solving for p, Initial residual = 0.0691549, Final residual = 6.58201e-07, No Iterations 28
GAMG: Solving for p, Initial residual = 0.121831, Final residual = 6.5816e-07, No Iterations 9
time step continuity errors : sum local = 1.04807e-06, global = 1.94758e-07, cumulative = 1.92987e-07
GAMG: Solving for p, Initial residual = 0.0167711, Final residual = 8.49387e-07, No Iterations 10
GAMG: Solving for p, Initial residual = 0.00363235, Final residual = 6.80705e-07, No Iterations 7
time step continuity errors : sum local = 1.24623e-06, global = 1.67559e-07, cumulative = 3.60546e-07
GAMG: Solving for p, Initial residual = 0.00116513, Final residual = 6.23309e-07, No Iterations 5
GAMG: Solving for p, Initial residual = 0.00037712, Final residual = 5.6651e-07, No Iterations 4
time step continuity errors : sum local = 1.04224e-06, global = -7.89613e-09, cumulative = 3.5265e-07
Setting traction on solid patch
Interpolating from fluid to solid using GGI/AMI interpolation
Total force (fluid) = (0.00181898 0.000254895 0.857794)
Total force (solid) = (0.0232158 0.0188301 -0.858651)
Evolving solid solver
Solving the momentum equation for D
Corr, res, relRes, matRes, iters
100, 6.22106e-05, 0.00011885, 0, 1
200, 6.97175e-07, 1.44222e-06, 0, 1
Both residuals have converged
209, 4.7143e-07, 9.79024e-07, 0, 1

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: 1.00004

Time = 1e-05, iteration: 3
Current fsi under-relaxation factor: 0.005
Maximal accumulated displacement of interface points: 15.0728
GAMG: Solving for cellMotionUx, Initial residual = 0.999999, Final residual = 2.44677e-05, No Iterations 1
GAMG: Solving for cellMotionUy, Initial residual = 0.999999, Final residual = 2.44333e-05, No Iterations 1
GAMG: Solving for cellMotionUz, Initial residual = 0.999935, Final residual = 0.000561837, No Iterations 1
GAMG: Solving for cellMotionUx, Initial residual = 0.000579899, Final residual = 5.08622e-07, No Iterations 2
GAMG: Solving for cellMotionUy, Initial residual = 0.000550867, Final residual = 5.30257e-07, No Iterations 2
GAMG: Solving for cellMotionUz, Initial residual = 0.00262411, Final residual = 1.22228e-06, No Iterations 3
Evolving fluid model: icoFluid
Courant Number mean: 1.11791 max: 36.2455 velocity magnitude: 30.468
DILUPBiCG: Solving for Ux, Initial residual = 0.956559, Final residual = 4.00994e-09, No Iterations 10
DILUPBiCG: Solving for Uy, Initial residual = 0.956539, Final residual = 8.31678e-09, No Iterations 10
DILUPBiCG: Solving for Uz, Initial residual = 0.226699, Final residual = 3.29184e-09, No Iterations 12

https://drive.google.com/open?id=1RC...P84ymIZ3mZMbAc

[Daniel_Khazaei]

I have not checked your setup yet but please consider the following general approach when dealing with any FSI problem:

1- Run fluid only case to ensure everything is behave as expected!

• Try to stabilize the solution as much as possible.

2- Run solid only case with an approximate force that will act on the
coupled boundary!

• Check for any unexpected behavior in numerical solution.

3- Now start to run a FSI case!

• If you are still facing convergence problem, you may try setting a couplingStartTime with coupled switch set to no which will allow the fluidModel to converge before transferring the forces to the solidModel.

I will take a look at your case when I'm free.