{"id":51930,"date":"2021-02-04T23:02:23","date_gmt":"2021-02-04T23:02:23","guid":{"rendered":"\/forum\/forums\/topic\/floating-point-exception-and-sigsegv-error-with-vof-model\/"},"modified":"2021-02-04T23:02:23","modified_gmt":"2021-02-04T23:02:23","slug":"floating-point-exception-and-sigsegv-error-with-vof-model","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/floating-point-exception-and-sigsegv-error-with-vof-model\/","title":{"rendered":"Floating point exception and SIGSEGV error with VOF model"},"content":{"rendered":"
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Hello all,<\/p>\n

I am looking at the fuel slosh in an automotive fuel tank using the VOF model with SST k-omega turbulence to track the surface of the fuel to ensure constant fuel delivery to the output. I am not using any UDF (time constraint left it for 'further work') and instead am using gravity to model the lateral acceleration in a worse case scenario.<\/p>\n

I ran the original design through and the simulation worked fine with results gathered. However after adding an additional baffle with 4mm holes, re-meshing and running it through with identical solver settings I am now getting a floating point error after 2 time steps.<\/p>\n

\/\/<\/p>\n

Flow time = 0.01999999955296516s, time step = 2<\/p>\n

168 more time steps<\/p>\n

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

Updating solution at time level N…<\/p>\n

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

Global Courant Number [Explicit VOF Criteria] : 4.80402<\/p>\n

done.<\/p>\n

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

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

100 1.0984e-02 4.3675e-03 8.3489e-04 3.3093e-04 4.3467e-04 1.5751e-03 0:00:23 50<\/p>\n

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

Error at Node 0: floating point exception<\/p>\n

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

Error at Node 1: floating point exception<\/p>\n

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

Error at Node 2: floating point exception<\/p>\n

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

Error at Node 3: floating point exception<\/p>\n

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

Error at Node 4: floating point exception<\/p>\n

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

Error at Node 5: floating point exception<\/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 z-momentum to enhance linear solver robustness.<\/p>\n

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

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

Divergence detected in AMG solver: z-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 k to enhance linear solver robustness.<\/p>\n

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

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

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

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

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

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

Divergence detected in AMG solver: x-momentum<\/p>\n

Divergence detected in AMG solver: y-momentum<\/p>\n

Divergence detected in AMG solver: z-momentum<\/p>\n

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

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

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

Divergence detected in AMG solver: x-momentum<\/p>\n

Divergence detected in AMG solver: y-momentum<\/p>\n

Divergence detected in AMG solver: z-momentum<\/p>\n

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

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

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

Divergence detected in AMG solver: x-momentum<\/p>\n

Divergence detected in AMG solver: y-momentum<\/p>\n

Divergence detected in AMG solver: z-momentum<\/p>\n

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

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

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

Divergence detected in AMG solver: x-momentum<\/p>\n

Divergence detected in AMG solver: y-momentum<\/p>\n

Divergence detected in AMG solver: z-momentum<\/p>\n

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

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

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

Divergence detected in AMG solver: x-momentum<\/p>\n

Divergence detected in AMG solver: y-momentum<\/p>\n

Divergence detected in AMG solver: z-momentum<\/p>\n

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

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

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

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

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

===============Message from the Cortex Process================================<\/p>\n

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

Compute processes interrupted. Processing can be resumed.<\/p>\n

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

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

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

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

Error Object: #f<\/p>\n

Registering ReportDefFiles, (*removed*)<\/p>\n

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

Calculation complete.<\/p>\n

\/\/<\/p>\n

I have tried a variety of suggestions in the forums but to no avail. I increased the time step from 0.01 to 0.001 but instead I get an instant SIGSEGV error before calculations start. When I've been troubleshooting this SIGSEGV error comes up whenever its not a floating point. I have tried reducing the momentum and turbulent kinetic energy under-relaxation factors but I either get no change or an instant SIGSEGV error again if I drop them low. I tried using double precision and got the same floating point error after 2 time steps.<\/p>\n

My mesh quality is: orthogonal quality avg=0.762 min=0.153 ,skewness avg=0.236 max=0.847. This is slightly worse than my first model but it should be acceptable from what I've read?<\/p>\n

I'm not using any inlets or outlets; I saw research projects\/papers in the past do it that way and it worked fine for me first time, could this be causing any problems?<\/p>\n

Here's a pic of the model for reference, sorry for the not optimal view can include more. The baffles are modelled as infinitely thin.<\/p>\n

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