Discussion Forum

Attached is a model with two geometries, where I am coupling 1D heat transport down a pipe to 2D axial symmetry conduction that occurs into the surrounding wall. I set up this model in a non-dimensional fashion, so that it solves for (dimensionless) F in 1D (where dimensionless F=temperature within the pipe/initial 2D block temperature) and (dimensionless) T in 2D axial symmetry (where dimensionless T=2D block temperature/initial 2D block temperature. When I run this model, temperature in the pipe approaches steady state. This is different from what I would expect with a derived analytical solution, which shows that water temperature in the pipe should change with time. I believe all of my equations are correct, so I was thinking my problem may be with the way Comsol is coupling between the two geometries. (If this is not the case, I can provide my derivations in another post if necessary.) I have used the extrusion coupling variables feature, extruding F from the 1D subdomain to a 2D boundary and extruding T from the same 2D boundary to the 1D subdomain. Does anyone see any problem with the way I have coupled between these two geometries?

Thank you,
Andrew Luhmann