Learning Forum

[snr1]

The VOF multiphase simulation ran without any error without any interphase mass transfer modelling. After loading the Multiphase interphase mass transfer UDF, the following error has been poped up. How to resolve this issue?

iter continuity x-velocity y-velocity o2-liq o2-gas vf-gas time/iter! 7639 solution is converged

7639 2.4544e-09 8.1801e-08 6.7103e-07 3.7238e-12 6.1584e-13 4.6369e-12 0:00:00 20

7640 1.4359e-02 1.8698e-04 9.2498e-04 5.2407e-05 1.1423e-02 1.1812e-02 0:00:00 19

7641 1.0450e+00 6.1819e-04 4.6209e-02 9.8945e-05 5.7200e-02 1.3164e+00 0:00:00 18

7642 6.1544e-01 9.7490e-02 9.3726e-02 1.8780e-02 2.9245e-03 2.5495e-02 0:00:00 17

7643 8.7324e+00 9.1611e-02 2.7645e-01 3.4739e-03 1.6859e-03 1.8404e+00 0:00:00 16

7644 7.0514e+00 7.6750e-02 8.0123e-02 7.8086e-03 3.0575e-02 1.9519e-02 0:00:00 15

Stabilizing liq-species-0 to enhance linear solver robustness.

7645 2.8414e+02 7.8766e-02 9.1858e-02 4.7772e-03 3.7671e-02 5.3241e-01 0:00:14 14

Stabilizing pressure coupled to enhance linear solver robustness.

Stabilizing pressure coupled using GMRES to enhance linear solver robustness.

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Experiencing convergence difficulties - temporarily relaxing and trying again...

Stabilizing pressure coupled to enhance linear solver robustness.

Stabilizing liq-species-0 to enhance linear solver robustness.

7646 2.5768e+02 4.2969e-02 4.9648e-02 4.4019e-03 6.7443e-03 4.0959e-02 0:00:10 13

7647 5.5790e+08 1.6041e-01 1.4770e-01 1.0774e-02 5.8977e-02 6.1154e-02 0:00:08 12

7648 2.0670e+09 2.8865e-02 2.0620e-02 1.5658e+02 2.9449e-02 1.9834e-02 0:00:06 11

Stabilizing gas-species-0 to enhance linear solver robustness.

Stabilizing gas-species-0 using GMRES to enhance linear solver robustness.

Divergence detected in AMG solver: gas-species-0

Divergence detected in AMG solver: gas-species-0

Divergence detected in AMG solver: gas-species-0

Divergence detected in AMG solver: gas-species-0

Error at host: floating point exception

Error at Node 0: floating point exception

Error at Node 1: floating point exception

Error at Node 2: floating point exception

Error at Node 3: floating point exception

Error: floating point exception

Error Object: #f

[Rob]

Can you revert to running without the mass transfer but monitor what mass the UDF thinks should be transferred? Ie dump the UDF output into a UDM. The error is showing the solver isn't happy, and it's probably linked to too much mass being transferred: you may have made an error or it may mean you need a smaller time step.

[snr1]

I simulated the case without UDF, and it ran without any errors. After loading the UDF, only the above error has popped up.

[Rob]

Which is the solver showing it's very unhappy. As it's only when the UDF is used it suggests the UDF is to blame: the typical cause is excessive mass transfer or rather excessive rate of mass transfer.