Purpose of FindGapIndexes and AddHeatGap..applying drichlet BC

Numerical methods and mathematical models of Elmer
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abasak123
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Purpose of FindGapIndexes and AddHeatGap..applying drichlet BC

Post by abasak123 »

Hello,
What is the purpose of FindGapIndexes subroutine, between line numbers 2045 to 2082) in HeatSolver? As far as I can understand, it is meant to find the nodes of the discontinous boundary that are coincident with the nodes of the boundary. Is it correct?

Also what does the AddHeatGap subroutine do?

In my problem, I wish to model a heat generation in a thin layer next to a boundary where temperature is specified. The domain is solid and I can write my own solver for this purpose. Using the approach followed in HeatSolver, I can make use of the the "Heat Gap" feature and create a discontinuity at the boundary where the temperature is specified. Then in the "Parent" set of nodes I will define the heat generation as heat flux (as is done in HeatSolver) and then programmatically apply the Dirichlet BC on the node indexes returned by FindGapIndexes subroutine. My question is, is it possible to apply Dirichlet conditions on specific nodes from the program itself? If so, can you point me towards the relevant piece of code?

Regards
Abhishek Basak
raback
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Re: Purpose of FindGapIndexes and AddHeatGap..applying drichlet BC

Post by raback »

Hi

When you have a jump in temperature and unknown temperatures at both sides you need some special FE stuff. There must be some way to introduce 2nd set of nodes at the same positions. There is no elementtype in Elmer that would directly fit this prescription. Instead the elements are standard boundary elements with two parent elements. The other set of indexes may then be found among the node indexes of the other parent element. So just technicality.

Now, in your case it sounds like you have only one unknown temperature at the interface if the temperature of the other side may be computed. So this would be suitable for Robin type of boundary condition where you define "External Temperature" (the known temperature) and "Heat Transfer Coefficient". Having heat gap boundary condition would be an overkill as you already know the temperature on other side.

-Peter
abasak123
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Re: Purpose of FindGapIndexes and AddHeatGap..applying drichlet BC

Post by abasak123 »

Hi Raback...
can you tell what does the subroutines do?
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