Mesh and Simulation Convergence

hellsblade.91 · February 19, 2018, 04:38

For the same mesh and geometry at a lower pressure my simulation runs and for a higher pressure I get floating point exception

Divergence detected in AMG solver: temperature
turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 2136 cells

reversed flow in 44 faces on pressure-outlet 7.

Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature
Divergence detected in AMG solver: temperature
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

Why do I get such an error at higher pressure(4bar) with the exact same mesh whereas it runs with a lower pressure (2 bar)

raghulvr · February 19, 2018, 05:09

It means that solver is not able to capture the turbulence occurring in the flow due to high pressure for your coarse mesh.
You should refine the mesh.

LuckyTran · February 19, 2018, 16:05

Probably it is due to a poor initial guess or inconsistent boundary conditions. Check your case setup and try to give it a really good initial guess. I.e. when you changed the pressure, did you change the initial temperature (&density?), k, epsilon and so on also?

February 19, 2018, 04:38	Mesh and Simulation Convergence	#1
hellsblade.91 Member Hells Blade Join Date: Nov 2017 Posts: 61 Rep Power: 8	For the same mesh and geometry at a lower pressure my simulation runs and for a higher pressure I get floating point exception Divergence detected in AMG solver: temperature turbulent viscosity limited to viscosity ratio of 1.000000e+05 in 2136 cells reversed flow in 44 faces on pressure-outlet 7. Divergence detected in AMG solver: temperature Divergence detected in AMG solver: temperature Divergence detected in AMG solver: temperature 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 Why do I get such an error at higher pressure(4bar) with the exact same mesh whereas it runs with a lower pressure (2 bar)

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February 19, 2018, 05:09		#2
raghulvr Member Rahul Join Date: Sep 2015 Posts: 39 Rep Power: 10	It means that solver is not able to capture the turbulence occurring in the flow due to high pressure for your coarse mesh. You should refine the mesh.

February 19, 2018, 16:05		#3
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	Probably it is due to a poor initial guess or inconsistent boundary conditions. Check your case setup and try to give it a really good initial guess. I.e. when you changed the pressure, did you change the initial temperature (&density?), k, epsilon and so on also?