June 15, 2023 at 10:47 amabhnv_01SubscriberI am trying to simulate a heat pipe in (3D) which has three sections:Evaporator - Constant heat flux (boundary conditions)
Condensor - Constant temperature (boundary conditions)
Adiabatic section - Zero heat flux (boundary conditions)
I am using VOF multiphase model -> Evaporation - condensation model -> Lee model.
Transient simulation with gravity and implicit body force formulation.
Time step size = 0.0001 (1E-04).The simulation runs well for about 10-12 seconds of flow time but then it stops due to this error"Divergence detected in AMG solver: pressure correction Stabilizing temperature to enhance linear solver robustness.
Stabilizing temperature using GMRES to enhance linear solver robustness.
Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: pressure correction"
Even though the simulation was running well for 10-12 seconds (100,000 time steps). What can be the possible reason for this error?
June 15, 2023 at 12:25 pmSRPAnsys Employee
This error message is an indication that equation is diverging. The most likely cause is that the under-relaxation factor (URF) for that equation is too large. Reduce the URF by 10%.
June 15, 2023 at 12:43 pmabhnv_01Subscriber
I had already changed the URFs.
Following are the URFs I have kept in my case:
Pressure - 0.5
Density - 1
Body forces - 1
Momentum - 0.2
Vaporazation of mass - 1
Energy - 0.8
June 15, 2023 at 1:11 pmRobAnsys Employee
Phase change and VOF currently don't always work well. If you look at the flow field a bit before divergence what is happening?
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