Computational Electromagnetics.
The time-dependent Maxwell Equations are solved with FDTD-method (finite-difference-time-domain).
Resolution: 500x500.
A thermal infrared EM-wave (300 micrometer wavelength point source, TM-mode) propagates and gets reflected at perfectly reflecting walls.
Reflecting open boundaries are implemented where PML-method (perfect-matching-layers) is deactivated.
Code was developed in Python. If I get enough likes, I'll upload the FDTD code on github.