Photothermal heating: dipole diapolo antenna example

Hello,
I have a very simple question,
in the example shown about the photothermal heating that takes a dipole antenna and compares it to diapolo antenna. When defining the boundary conditions: you define two interface
1-air-antenna
2-air-Al2O3 substrate
We don’t need to specify the antenna-substrate interface?
Thank you

Dear @abeer.al-mohtar

No! the solid boundaries are predefined by heat equations and software does not need (and won’t allow you) to define these boundaries. In simple word, you need to specify BC for the simulation region and objects, and objects-air interface.

I was checking the tutorial of this simulation and I got a question regarding the thermal boundaries: I noticed that the only thermal boundaries defined are at the bottom of the substrate. However at the sides of the substrate there are not thermal boundaries. Does it means it is insulating? And why it is so?

Thanks a lot for your time.

Kind regards,

Gabriel

Yes, they are insulating boundaries. I think we discussed this in an earlier post:

Regarding second part of the question: since in this example we assume that geometry is periodic, temperature profiles on cell # m-1 , m, and m+1 are identical. In other words, temperature on two sides of the edge of cell #m are identical. These points are denoted by green stars in the figure below, and red box shows the boundaries of cell #m:

As a result, since there is no temperature difference between these points, you do not expect to have a net heat flow from one cell to another, or in another words, they can be considered as insulating BCs.

To summarize, since geometry is periodic, temperature profile on all cells are identical and there will not be a net heat flow from one cell to another.