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Subdomain or Boundary Conditions?
Posted 11.08.2011, 08:24 GMT-4 Version 3.5a, Version 4.1, Version 4.2 1 Reply
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Hi,
I'm using the heat transfer module to simulate the Temperature distribution over a substrate, but i don't get the expected results unless i apply the heat source on all boundaries and i get different results when i apply it on the subdomain as a whole.
My question is : if i ignore th Sub-Domain Settings and put the Q = 0 does using the boundary settings tells the sovler to Ignore the general heat equation and solve only according to that equation shown in the boundary settings?
Because then i don't think my simulation will be valid as i'm supposed to simulating for the general heat transfer PDE.
Thanks
I'm using the heat transfer module to simulate the Temperature distribution over a substrate, but i don't get the expected results unless i apply the heat source on all boundaries and i get different results when i apply it on the subdomain as a whole.
My question is : if i ignore th Sub-Domain Settings and put the Q = 0 does using the boundary settings tells the sovler to Ignore the general heat equation and solve only according to that equation shown in the boundary settings?
Because then i don't think my simulation will be valid as i'm supposed to simulating for the general heat transfer PDE.
Thanks
1 Reply Last Post 14.08.2011, 04:08 GMT-4
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Posted:
1 decade ago
Hi
It is not obvious to understand fully your issue there, if you apply a heat source (positive or negative) to ALL boundaries, for me you have a system "running away", except if your balance of heat in/out is perfectly balanced AND there is no numrical noise (with is only a theoretical possibility). For me you need at leas one defind "constant" temperature boundary, so that the system might adapt the heat flux to get the system to an energy equilibrium
It's like in structural, you need to fix 6 DoF (in 3D) to have the structure stable somewhere, then you can see the deformations. This means that COMSOL might adapt the reaction forces and moments on these boundaries to get a stable energy balance
But I might have misunderstod your explanations too ;)
Another suggestion: use if possible v4.2, latest patch: it is far more stable than the early 4 versions, and is now far more advanced than 3.5, "mais j'admet que les goûts et les couleurs sont des sujet délicats" ;)
--
Good luck
Ivar
It is not obvious to understand fully your issue there, if you apply a heat source (positive or negative) to ALL boundaries, for me you have a system "running away", except if your balance of heat in/out is perfectly balanced AND there is no numrical noise (with is only a theoretical possibility). For me you need at leas one defind "constant" temperature boundary, so that the system might adapt the heat flux to get the system to an energy equilibrium
It's like in structural, you need to fix 6 DoF (in 3D) to have the structure stable somewhere, then you can see the deformations. This means that COMSOL might adapt the reaction forces and moments on these boundaries to get a stable energy balance
But I might have misunderstod your explanations too ;)
Another suggestion: use if possible v4.2, latest patch: it is far more stable than the early 4 versions, and is now far more advanced than 3.5, "mais j'admet que les goûts et les couleurs sont des sujet délicats" ;)
--
Good luck
Ivar