{"id":163446,"date":"2021-10-27T13:59:04","date_gmt":"2021-10-27T13:59:04","guid":{"rendered":"\/forum\/forums\/topic\/axisymmetric-problem-divergence-detected-in-amg-solver\/"},"modified":"2021-10-29T11:28:56","modified_gmt":"2021-10-29T11:28:56","slug":"axisymmetric-problem-divergence-detected-in-amg-solver","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/axisymmetric-problem-divergence-detected-in-amg-solver\/","title":{"rendered":"Axisymmetric Problem: Divergence detected in AMG solver?"},"content":{"rendered":"
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Hello,<\/p>\n

<\/p>\n<\/p>\n

I am trying to simulate a bottle with a hand pump from which glycerin is being discharged. I wanted to model this using the "axisymmetric model". However, the axisymmetric option never worked for me. I checked my mesh, tried a variety of meshes with different skewness, orthogonality, etc. I have also made sure that my symmetry axis is on the x-axis, but the result was always the same.  The simulation crashes even before the first iteration and I am getting the following error (note that when I use planar model, everything works perfectly):<\/p>\n

<\/p>\n<\/p>\n

—————————–<\/p>\n

Global Courant Number [Explicit VOF Criteria] : 0.16369<\/p>\n

 done.<\/p>\n

<\/p>\n<\/p>\n

 iter continuity x-velocity y-velocity  time\/iter<\/p>\n

    Stabilizing x-momentum to enhance linear solver robustness.<\/p>\n

    Stabilizing x-momentum using GMRES to enhance linear solver robustness.<\/p>\n

<\/p>\n<\/p>\n

Divergence detected in AMG solver: x-momentum    Stabilizing y-momentum to enhance linear solver robustness.<\/p>\n

    Stabilizing y-momentum using GMRES to enhance linear solver robustness.<\/p>\n

<\/p>\n<\/p>\n

Divergence detected in AMG solver: y-momentum    Stabilizing pressure correction to enhance linear solver robustness.<\/p>\n

    Stabilizing pressure correction using GMRES to enhance linear solver robustness.<\/p>\n

<\/p>\n<\/p>\n

Divergence detected in AMG solver: pressure correction    Stabilizing pressure correction to enhance linear solver robustness.<\/p>\n

    Stabilizing pressure correction using GMRES to enhance linear solver robustness.<\/p>\n

<\/p>\n<\/p>\n

Divergence detected in AMG solver: pressure correction<\/p>\n

Error at host: floating point exception<\/p>\n

<\/p>\n<\/p>\n

——————————-<\/p>\n

<\/p>\n<\/p>\n

The details of my model are as follows:<\/p>\n

-Transient, pressure-based, axisymmetric<\/p>\n

-VoF – glycerin and air<\/p>\n

-Boundary conditions: <\/p>\n

       -inlet: velocity inlet 0.243 mm\/sec<\/p>\n

       -outlet: pressure outlet 0 gauge pressure<\/p>\n

       -wall-slip boundary conditions everywhere else<\/p>\n

Methods: PISO<\/p>\n

Controls: Pressure-0.3, density-1, body forces-1, momentum-07<\/p>\n

Residuals: 0.001<\/p>\n

Initialization: standard – glycerin volume fraction:1<\/p>\n

Calculations: Adaptive – Time step size 0.00001, 20000 time steps, 20 iterations\/time-step<\/p>\n

<\/p>\n<\/p>\n

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