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How to use the output (solution) of one boundary in a model as the input (initiation condition) of the other boundary in another model

Posted Apr 23, 2012, 4:15 p.m. EDT Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.2a 4 Replies

Rocksmida
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Hi, everybody!

I have a question about the boundary settings in the CFD module. I built an open channel and calculated the fully developed turbulent flow. Now I want to build another channel, which has the same cross section with the first one. The two channels are in fact connected, but I build the second one because it has an obstacle in it. And I want to use the solution at the outlet boundary in the first model as the input at the inlet boundary in the second model. Do anyone know how can I accomplish this? Any comments are welcomed and appreciated. Thank you!
4 Replies Last Post Jul 5, 2013, 8:19 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Apr 24, 2012, 2:57 p.m. EDT
Hi

I would suggest two posible ways. One is to export the relevant results, over the boundary to an interpolation data file and then import it into a function and use that as an explicit initial condition in your second run. But this is only practical for "small" simulatins as your file(s) might become very large and take a long time to process i this way.

THe second way is to model everything in the under the same model tree, add both geoemtries one after the other, set up two physics, one for each segment of the geometry, and add two studies, one for each and use the dependent variables intial condition to link the two. I believe this should work, but I must admit I havent tried it out like that before ;)

--
Good luck
Ivar
Hi I would suggest two posible ways. One is to export the relevant results, over the boundary to an interpolation data file and then import it into a function and use that as an explicit initial condition in your second run. But this is only practical for "small" simulatins as your file(s) might become very large and take a long time to process i this way. THe second way is to model everything in the under the same model tree, add both geoemtries one after the other, set up two physics, one for each segment of the geometry, and add two studies, one for each and use the dependent variables intial condition to link the two. I believe this should work, but I must admit I havent tried it out like that before ;) -- Good luck Ivar
Rocksmida
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Posted: 1 decade ago Apr 25, 2012, 12:53 p.m. EDT
Thank you very much Ivar. Actually I figured out the first approach, and I tried and the result is satisfying. For the second approach, I think it will make the simulations easier but I don't know how to apply it, either. I am also thinking about the "model couplings" function. If I build two models, can I couple the outlet of the first model to the inlet of the second one? I tried a simple example. And it doesn't work. Do you have any experience on the "model coupling" functions? Thank you
Thank you very much Ivar. Actually I figured out the first approach, and I tried and the result is satisfying. For the second approach, I think it will make the simulations easier but I don't know how to apply it, either. I am also thinking about the "model couplings" function. If I build two models, can I couple the outlet of the first model to the inlet of the second one? I tried a simple example. And it doesn't work. Do you have any experience on the "model coupling" functions? Thank you
Mustafa Koz
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Posted: 1 decade ago Jul 12, 2012, 4:33 p.m. EDT
May I ask how you achieved the first approach? I am also trying to export the data on a surface in a 3D geometry.

Thanks in advance!
May I ask how you achieved the first approach? I am also trying to export the data on a surface in a 3D geometry. Thanks in advance!
Maxime Cordova
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Posted: 1 decade ago Jul 5, 2013, 8:19 a.m. EDT
Dear M. Ruhl,

Thank's a lot for your answer, it is indeed very efficient to solve this way (successive studies) and and think I will use it in order not to have too many functions to define. I will also try to find out what was wrong with my first method but your solution seems to be well appropriated.

Thank you very much again

Maxime
Dear M. Ruhl, Thank's a lot for your answer, it is indeed very efficient to solve this way (successive studies) and and think I will use it in order not to have too many functions to define. I will also try to find out what was wrong with my first method but your solution seems to be well appropriated. Thank you very much again Maxime

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