I am trying to solve the inhomogeneous wave equation on COMSOL. I strongly suspect that the RF module can do this, but my license does not include it and I don't intend to waste any more of my advisor's funds.
The homogenous, time harmonic case of the wave equation is simply the Helmholtz equation, which is already built in COMSOL. This can be solved very nicely. Now, the problem is that I want to vary the absorption coefficient "a" according to the material of the regions I define. This will allow me to capture the effect of reflection/refraction under different geometries.
Unfortunately, unlike the pre-built physics models, there is no option "From material" for the absorption coefficient. I am only allowed to enter a constant or an expression. After reading through the documentation, I figured that I could put a variable there, and define the variable to be a different value depending on which domain it is in.
As simple as it sounds, I can't figure out how to do this. I understand that I should be able to write an "expression" by accessing the domain variables already defined, but I can't find any examples of this. The documentation is either woefully inadequate in this regard or I am just looking at the wrong place.
Any help will be greatly appreciated, especially if it has an example!
The homogenous, time harmonic case of the wave equation is simply the Helmholtz equation, which is already built in COMSOL. This can be solved very nicely. Now, the problem is that I want to vary the absorption coefficient "a" according to the material of the regions I define. This will allow me to capture the effect of reflection/refraction under different geometries.
Unfortunately, unlike the pre-built physics models, there is no option "From material" for the absorption coefficient. I am only allowed to enter a constant or an expression. After reading through the documentation, I figured that I could put a variable there, and define the variable to be a different value depending on which domain it is in.
As simple as it sounds, I can't figure out how to do this. I understand that I should be able to write an "expression" by accessing the domain variables already defined, but I can't find any examples of this. The documentation is either woefully inadequate in this regard or I am just looking at the wrong place.
Any help will be greatly appreciated, especially if it has an example!