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3.5a and 4.2
Posted Nov 21, 2013, 10:59 a.m. EST Version 3.5a, Version 4.2 2 Replies
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Hi to all,
I am trying for the first time the new version of COMSOL, while until now i could work only on 3.5a.
I have to do a multiphysics simulation including heat transfer and fluidodynamics.
The phenomenon I have to model is a metal box including some heat sources, and crossed by a pipe through which flows fresh water.
In 3.5a I used htgh and chns.
In chns i decided the pressure of ater at inlet and at outlet, and the properties of the liquid.
Now I have to perform the same simulation with the new version of COMSOL.
With the first try, I opened with the 4.2 the same file created in 3.5a, and clicked on 'compute'.
It worked (and the simulation is faster and more accurate), but the results are different (for example i find higher temperature, around 10 °C more, in the output of the simulation... what is the reason of this?
Now I'm trying to start a model from zero in 4.2, I see that there are more physics available, and I'm not sure wich are the ones I should use... at the moment I'm using ht and nitf... i succeded to do the simulation, and setting the same parameters that I used in the previous simulations i have again different results, with output temperature further higher...
When I simulate just heat transfer, without considering fluidodynamics, I have more consistent results with all the solver... why there is this problem with fluidodynamics?
thanks to anybody who could help
Francesco
I am trying for the first time the new version of COMSOL, while until now i could work only on 3.5a.
I have to do a multiphysics simulation including heat transfer and fluidodynamics.
The phenomenon I have to model is a metal box including some heat sources, and crossed by a pipe through which flows fresh water.
In 3.5a I used htgh and chns.
In chns i decided the pressure of ater at inlet and at outlet, and the properties of the liquid.
Now I have to perform the same simulation with the new version of COMSOL.
With the first try, I opened with the 4.2 the same file created in 3.5a, and clicked on 'compute'.
It worked (and the simulation is faster and more accurate), but the results are different (for example i find higher temperature, around 10 °C more, in the output of the simulation... what is the reason of this?
Now I'm trying to start a model from zero in 4.2, I see that there are more physics available, and I'm not sure wich are the ones I should use... at the moment I'm using ht and nitf... i succeded to do the simulation, and setting the same parameters that I used in the previous simulations i have again different results, with output temperature further higher...
When I simulate just heat transfer, without considering fluidodynamics, I have more consistent results with all the solver... why there is this problem with fluidodynamics?
thanks to anybody who could help
Francesco
2 Replies Last Post Nov 26, 2013, 9:36 a.m. EST
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Posted:
1 decade ago
If i wasn't clear enough, please ask.
I still can't undestand how it is possible that two versions of the same simulator can converge on different solutions.
I still can't undestand how it is possible that two versions of the same simulator can converge on different solutions.
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Posted:
1 decade ago
I find out that that surely the simulation done in 4.2 with ht and nitf is not consistent (varying some parameters has not the trend I expect), I think that there is some meshing issue.
But I still don't understand how it is possible that the same model (with the same meshing) can give different results if opened with 2 different versions of comsol... it is possible that with different versions there is a different mesh required?
But I still don't understand how it is possible that the same model (with the same meshing) can give different results if opened with 2 different versions of comsol... it is possible that with different versions there is a different mesh required?