Discussion Forum

Good evening everyone,

I'm trying to set up a 2D conjugate heat transfer simulation, and I have a doubt about the boundary conditions I should set in my model. I've attached the mph file of my simulation.

I have two rectangular adjacent domains; one is fluid and the other is solid. The fluid domain is heated by a constant radiative heat flux on the top (i.e.: by a light source), which is absorbed and gradually extincted by the fluid itself. To model the extinction of light, I followed the instructions of this tutorial (https://www.comsol.com/blogs/modeling-laser-material-interactions-with-the-beer-lambert-law/), which is similar to the physics of my problem (I considered a monochromatic collimated source of light, with no scattering, refraction or reflection, having an input flat profile of 1000 W/m^2 intensity).

The solid domain exchanges heat with the fluid through conduction (since the radiation comes from the top, the fluid is stratified and there are no convective motions), and is interfaced with the external environment (still air) on its right side: so, I implemented a natural convective heat flux on that boundary. The whole system is symmetrical along the left boundary of the fluid domain, as regards both the geometry, the temperature and the velocity fields.

As regards the remaining heat transfer boundary conditions (and here is my doubt), I’d like to set them all as conductive heat fluxes, because I know that both the solid and fluid domains are in contact with solid materials on their top and bottom sides (I did not include these additional solid domains in my model, to avoid undesired complications at this stage of my study).

So, my question is: is it correct to implement the conductive heat flux boundary conditions, simply setting the general inward heat flux q0 equal to zero, as I tried to do in the attached model?

Thank you very much in advance to anyone for her/his help. Kind regards Daniele