I am doing transient simulation for what is called friction stir welding processes of Aluminium 6061, so far the model is facing a problem. The problem takes place when I use the UDF for defining Aluminium viscosity which is a temperature dependent property. Although, the UDF seemed successfully Interpreted, the next error appeared when running the model.
# Divergence detected in AMG solver: x-momentum -> Increasing relaxation sweeps!
# You may try the enhanced divergence recovery with (rpsetvar 'amg/protective-enhanced? #t)
Error: Divergence detected in AMG solver: x-momentum
Error: Divergence detected in AMG solver: x-momentum
Error Object: #f
Registering SurfaceMonitors, ("surf-mon-1.out")
Registering Udf, ("C:\Users\u1473797\Desktop\Deforming_files\dp0\FFF\Fluent\mu.c.C")
Hello! If the problem is your UDF, may be you should try to define the viscosity by piecewise-linear table instead of UDF. Another way is to check the ENERGY under-relaxation factor, solver often fails during start-up if factor=1, change to 0.9, then solve some iteration and let it back again to 1.
Good luck
I will side with Yury on that by decreasing the relaxation factors. One thing to also check is your time scale. The time scale should be carefully selected depending on the kind of process or problem u solving. Goodluck!
Several times I did face the same problems and I think relaxation factor is not only the prime factor, but we should also consider the model (laminar or turbulent) that might have a great influence in this problem..
- Badges
- Science topic