Discussion Forum

Hello,

I am a new user of COMSOL, so if anyone could give any helpful inputs, I would be very grateful. I am trying to model conductive and convective heat transfer on a device that contains an array of microchannels with rectangular cross-sections. This device pretty much looks like a cinder block, but with many more "holes" or channels through it. I added a heat flux on the top surface/boundaries of the device. I expect heat to conduct through this layer (which is very thin) until it reaches the channels, which I have water flowing through. It is here where I want to model convective cooling, so that the water flow can further enhance the transfer of heat.

I tried to use the Conjugate Heat Transfer study, but so far I have been getting invalid results (such as zero or near-zero flow-rate and incredibly high temperatures). I am currently trying to add "Convective Cooling" to the study . I thought it would be natural to use the walls of the channels as the boundaries for "Convective Cooling," but these boundaries are labeled "not applicable," which I think is because these are already boundaries set in "Wall 1." I am also interested in using "Convective Cooling" because I can define my own heat transfer coefficient.

I suspect that there is a way to somehow couple the two modes of heat transfer so that T_ext, which is a value I need to input for convective cooling, is set to depend on the conductive heat transfer that reaches the channels.

If anyone could provide some input regarding the non-applicable boundaries and/or coupling, I would greatly appreciate it.

Thank you in advance.