control number iterations per equation

CeesH · March 2, 2016, 08:27

Hi all,

When I'm running a transient simulation of a gas-liquid flow (with population balance), it seems the population balance equations cannot 'keep up' with the volume fraction equation.

Things tend to get much better if I disable volume fraction eq. for a while (under solution controls), converge the pop. balance variables, enable volume fraction for a few steps again, and so on. But of course, it's not really viable to keep on doing this by hand. Is there anyway to automate this? so say, execute 10 population balance iterations for every volume fraction iteration?

Best,
Cees

LuckyTran · March 2, 2016, 12:05

Can this be done through under relaxation factor instead? It doesn't disable the equation but does slow its changes.

CeesH · March 2, 2016, 12:25

hm, maybe if I go really low. with UR for vol. frac. around 0.1 it doesn't seem to be helping a lot yet, but I'll play with it a bit more

March 2, 2016, 08:27	control number iterations per equation	#1
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	Hi all, When I'm running a transient simulation of a gas-liquid flow (with population balance), it seems the population balance equations cannot 'keep up' with the volume fraction equation. Things tend to get much better if I disable volume fraction eq. for a while (under solution controls), converge the pop. balance variables, enable volume fraction for a few steps again, and so on. But of course, it's not really viable to keep on doing this by hand. Is there anyway to automate this? so say, execute 10 population balance iterations for every volume fraction iteration? Best, Cees

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March 2, 2016, 12:05		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,672 Rep Power: 65	Can this be done through under relaxation factor instead? It doesn't disable the equation but does slow its changes.

March 2, 2016, 12:25		#3
CeesH Senior Member Cees Haringa Join Date: May 2013 Location: Delft Posts: 607 Rep Power: 0	hm, maybe if I go really low. with UR for vol. frac. around 0.1 it doesn't seem to be helping a lot yet, but I'll play with it a bit more