# Thermal contact resistance in PDE toolbox

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Luca Lazzoni on 5 Nov 2020
Commented: Luca Lazzoni on 13 Nov 2020
Hi, I'm modelling an axisymmetric 2D model of a cylinder made of two layer of different metals. The geometry I built is made of two rectangles with one edge in common. I'm trying to find a method to define the contact resistance between this two rectangles, at the moment by using the thermalBC command applied on such common edge, but without any results. Is there someone who can help me?

Ravi Kumar on 5 Nov 2020
Hi Luca,
Interface conditions like thermal contact resistance are not yet supported in PDE Toolbox.
Regards,
Ravi
Luca Lazzoni on 13 Nov 2020
Thank you for the answer. I have tried to find some sort of workaround for that and I came up with something that seems not to work anyway, but I'd like to understand why, I hope you can help me also with that. So the idea is to add an if cycle to the function which define the thermal conductivity of the materials (I am already using a dependence on the temperature). Here the code
function lambda_inc = IncCondPDE(location, state)
T = [294; 366; 477.6; 588.7; 699.8; 810.9; 922; 1033.15; 1144.26; 1255.37; 1366.5];
lambda = [11.4; 12.5; 14.4; 16.1; 17.9; 19.6; 21.3; 23.2; 24.9; 26.8; 28.7];
if location.x > 0.0236
lambda_inc = 0.0001;
else
lambda_inc = pchip(T, lambda, state.u);
end
end
The contact should be at 0.024. I use a 0.2mm quadratic mesh, so I was supposing that if I create such condition for which elements, or at least some nodes, are above the distance threshold they results to have a very low conductivity. I tried to see if the cycle enters the first case by setting a breakpoint on the lambda_inc=0.0001, but it never stops. I tried proceeding step by step and I noticed that the solver create the location and state structures with integer elements at first, but then switch to vectors. I look inside the vectors and noticed that location.x has actually some values over 0.0236. I don't really understand why it's not working.

R2020b

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