Residual and Imbalance oscillating

Spookz · December 12, 2012, 05:49

Hello,

i hope you can help me.

I am currently simulating an autoclave, doing sensitivity analysis on mesh.
Its a simple transient flow simulation without heat transfer.
BCs are:

Reference Pressure: 5 bar
Air at 25°C
Inlet: Mass flow
Outlet: Opening (0Pa Opening Pressure)
Initial condition for Fluid: velocity 0 m/s, p=0 bar

I am simulating the first 3 secs of air flow into the autoclave.

1) I have set the residual to 10^-5 and the monitor show, that all equations converge. Anyway residual is still oscillating between 10^-5 and 10^-6.
What does that mean? Has convergence been reached?

2) The imbalance plot does also show oscillation between 10^-2 and 10^-4.
As this is a percentage value, is a value of 10^-2 sufficient for convergence?

3) Do the oscillations have influence on convergence?

Thanks in advance

ghorrocks · December 12, 2012, 16:19

See the FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria

December 12, 2012, 05:49	Residual and Imbalance oscillating	#1
Spookz New Member Felix Join Date: Nov 2012 Posts: 15 Rep Power: 13	Hello, i hope you can help me. I am currently simulating an autoclave, doing sensitivity analysis on mesh. Its a simple transient flow simulation without heat transfer. BCs are: Reference Pressure: 5 bar Air at 25°C Inlet: Mass flow Outlet: Opening (0Pa Opening Pressure) Initial condition for Fluid: velocity 0 m/s, p=0 bar I am simulating the first 3 secs of air flow into the autoclave. 1) I have set the residual to 10^-5 and the monitor show, that all equations converge. Anyway residual is still oscillating between 10^-5 and 10^-6. What does that mean? Has convergence been reached? 2) The imbalance plot does also show oscillation between 10^-2 and 10^-4. As this is a percentage value, is a value of 10^-2 sufficient for convergence? 3) Do the oscillations have influence on convergence? Thanks in advance

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December 12, 2012, 16:19		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,701 Rep Power: 143	See the FAQ: http://www.cfd-online.com/Wiki/Ansys...gence_criteria