2 domains - 2 physical timesteps? How to?

flattie · March 30, 2009, 13:36

I have 2 fluid domains with a solid between them. How can I set two different physical timesteps, without resorting to autotimestepping, which I don't want to use? The size of my domains is vastly different and the timescale needed to get the small domain to converge leads to very slow convergence on the large domain.

Thanks!

Craig Hildreth

rikio · March 30, 2009, 21:42

Local Timescale Factor can be used to set different timescales for different domains automatically. Please refer to section of "Steady State Time Scale Control" in HELP.
Wish it helps.

flattie · March 31, 2009, 12:31

Thanks, but doesn't Localtimescale factor have a different timestep on an element basis rather than a domain one? I want to set the timestep for the domain as a whole.

stumpy · April 4, 2009, 21:44

You can do this, but it's CCL only. Essentially copy the entire SOLVER CONTROL section and paste it under the DOMAIN section. Delete all the parameter except the timescale control parameters.
Mike

rikio · April 5, 2009, 05:01

Stumpy,

Does it work? I will have a try on this to check this "new" feature...hehe

stumpy · April 5, 2009, 20:27

Yeh, it works, I've used it before. You can do phase-specific timescales too in a similar way by pasting into the FLUID object of a domain. If you know how to read the RULES file (<install dir>/etc/RULES) you can see that SOLVER CONTROL is a valid child of a DOMAIN object.

March 30, 2009, 13:36	2 domains - 2 physical timesteps? How to?	#1
flattie New Member Craig Hildreth Join Date: Mar 2009 Posts: 22 Rep Power: 17	I have 2 fluid domains with a solid between them. How can I set two different physical timesteps, without resorting to autotimestepping, which I don't want to use? The size of my domains is vastly different and the timescale needed to get the small domain to converge leads to very slow convergence on the large domain. Thanks! Craig Hildreth

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March 30, 2009, 21:42		#2
rikio Senior Member Rikio Join Date: Mar 2009 Location: SH, China Posts: 182 Blog Entries: 1 Rep Power: 17	Local Timescale Factor can be used to set different timescales for different domains automatically. Please refer to section of "Steady State Time Scale Control" in HELP. Wish it helps.

March 31, 2009, 12:31		#3
flattie New Member Craig Hildreth Join Date: Mar 2009 Posts: 22 Rep Power: 17	Thanks, but doesn't Localtimescale factor have a different timestep on an element basis rather than a domain one? I want to set the timestep for the domain as a whole.

April 4, 2009, 21:44		#4
stumpy Senior Member Join Date: Apr 2009 Posts: 531 Rep Power: 21	You can do this, but it's CCL only. Essentially copy the entire SOLVER CONTROL section and paste it under the DOMAIN section. Delete all the parameter except the timescale control parameters. Mike

April 5, 2009, 05:01		#5
rikio Senior Member Rikio Join Date: Mar 2009 Location: SH, China Posts: 182 Blog Entries: 1 Rep Power: 17	Stumpy, Does it work? I will have a try on this to check this "new" feature...hehe

April 5, 2009, 20:27		#6
stumpy Senior Member Join Date: Apr 2009 Posts: 531 Rep Power: 21	Yeh, it works, I've used it before. You can do phase-specific timescales too in a similar way by pasting into the FLUID object of a domain. If you know how to read the RULES file (<install dir>/etc/RULES) you can see that SOLVER CONTROL is a valid child of a DOMAIN object.