Interpolate solution onto only some target domains

gotang · August 15, 2016, 08:29

Hi all,

I'm running a simulation in CFX with fluid domains [Domain1,Domain2,Domain3]. I would like to interpolate some of the solution onto a new simulation with fluid domains [Domain1,Domain2,Domain4] - in other words, the first two fluid domains are identical to my previous simulation, but the third is changed completely. The trouble is that Domain 3 and Domain 4 do not overlap at all (these domains represent cooling holes, and so I am effectively changing the location of the cooling feeds entirely), so the Interpolator gives the error: "There are no mapped nodes in the domain."

Is there any way that I can tell CFX to initialise Domain4 from scratch, while still interpolating the previous results onto Domain1 and Domain2? I know that in Fluent this is possible (by first initialising the whole solution, then interpolating just the required domains), but I haven't been able to find a way of doing this in CFX.

Thanks!

ghorrocks · August 15, 2016, 08:47

You can set initial condition values by domain. So if you set an initial condition on domain 4 it will hopefully use that instead of interpolated values which don't give you anything.

gotang · August 15, 2016, 09:27

The trouble with that is that the interpolator refuses to run at all unless all target domains have an "Interpolation Mapping" set to them, and if I try to map Domain3 onto Domain4 (intending to override the interpolation using the "Initial Values" setting), the interpolator gives the "no mapped nodes" error.

gotang · March 6, 2017, 08:12

Resurrecting an old thread and answering my own question, I've finally found the solution so I thought I'd post it here for the next person who faces this problem!

The answer is essentially what ghorrocks was suggesting (Thanks!), but I'd got the specifics of how to initialise it incorrect (definitely my fault, not his). You need to set up the "Initial Values Specification" under "Execution Control", but without specifying anything under "Interpolation Mapping". CFX will then do its best effort at working out which domains to map onto from the source domain. Additionally, you specify "Domain Initialisation" for the domain that you don't want to interpolate/is not available in your previous solution (double-click on the domain name in the tree, look for the "Initialisation" tab), and set up an initialisation there. Don't include a "Global initialisation" entry in your tree.

With this setup, CFX will first attempt to initialise the domain from your Initial Values specification(s) (you can specify multiple previous runs to start from, and CFX will take its best guess on the appropriate mapping), but will then reinitialise the domain(s) you have specified manually.

August 15, 2016, 08:29	Interpolate solution onto only some target domains	#1
gotang New Member Brian Join Date: Mar 2009 Posts: 17 Rep Power: 17	Hi all, I'm running a simulation in CFX with fluid domains [Domain1,Domain2,Domain3]. I would like to interpolate some of the solution onto a new simulation with fluid domains [Domain1,Domain2,Domain4] - in other words, the first two fluid domains are identical to my previous simulation, but the third is changed completely. The trouble is that Domain 3 and Domain 4 do not overlap at all (these domains represent cooling holes, and so I am effectively changing the location of the cooling feeds entirely), so the Interpolator gives the error: "There are no mapped nodes in the domain." Is there any way that I can tell CFX to initialise Domain4 from scratch, while still interpolating the previous results onto Domain1 and Domain2? I know that in Fluent this is possible (by first initialising the whole solution, then interpolating just the required domains), but I haven't been able to find a way of doing this in CFX. Thanks!

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August 15, 2016, 08:47		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	You can set initial condition values by domain. So if you set an initial condition on domain 4 it will hopefully use that instead of interpolated values which don't give you anything.

August 15, 2016, 09:27		#3
gotang New Member Brian Join Date: Mar 2009 Posts: 17 Rep Power: 17	The trouble with that is that the interpolator refuses to run at all unless all target domains have an "Interpolation Mapping" set to them, and if I try to map Domain3 onto Domain4 (intending to override the interpolation using the "Initial Values" setting), the interpolator gives the "no mapped nodes" error.

March 6, 2017, 08:12		#4
gotang New Member Brian Join Date: Mar 2009 Posts: 17 Rep Power: 17	Resurrecting an old thread and answering my own question, I've finally found the solution so I thought I'd post it here for the next person who faces this problem! The answer is essentially what ghorrocks was suggesting (Thanks!), but I'd got the specifics of how to initialise it incorrect (definitely my fault, not his). You need to set up the "Initial Values Specification" under "Execution Control", but without specifying anything under "Interpolation Mapping". CFX will then do its best effort at working out which domains to map onto from the source domain. Additionally, you specify "Domain Initialisation" for the domain that you don't want to interpolate/is not available in your previous solution (double-click on the domain name in the tree, look for the "Initialisation" tab), and set up an initialisation there. Don't include a "Global initialisation" entry in your tree. With this setup, CFX will first attempt to initialise the domain from your Initial Values specification(s) (you can specify multiple previous runs to start from, and CFX will take its best guess on the appropriate mapping), but will then reinitialise the domain(s) you have specified manually.