Learning Forum

[AleksandrZ]

Dear support team,

I am using the HEAT solver, and my simulation region includes a region with air, which is represented by a rectangle, with assigned material "Convective Gas". (I used the file from this example https://optics.ansys.com/hc/en-us/articles/360042833673-Thermally-tuned-waveguide-FDE- as a template). I noticed, that after the simulation is over, the results inside the solver itsef and inside the temperature monitor are limited by the region which is in contact with air. Is it normal, or there is something wrong with the simulation settings? It is also the case for your example, the temperature map seems to be only defined inside the solids. On the temperature map that the monitor returns, it's obvious, that the highest Z coordinate corresponds to the polymer-air boundary.

I find it also strange that the highest temperature in the simulation does not change when I reduce the gap between the air surface and my device, even though I would expect the convection to improve the heat dissipation, if the device is closer to the surface.

[Amrita Pati]

Hi Aleksandr,

It is not due to incorrect simulation settings. The air section is not included in the temperature map because it is a fluid. Fluids in the HEAT solver are only used to enforce boundary conditions. The heat transfer equations are solved only in the solids based on the boundary conditions defined at the solid-fluid interfaces, which specifically includes convection at the boundaries.  

More information on fluids can be found on the following page:
https://optics.ansys.com/hc/en-us/articles/360034919173-Fluid-material-model-properties
 
Please let me know if you have more questions.

Regards,
Amrita