Скачать или смотреть Energy of a linear wave crossing an octagon with refractive index 2

This video shows the same simulation as the video    • A linear wave crossing an octagon with ref...   , but with a different color coding, representing the energy of the wave, averaged over different time periods, instead of the wave height. An oscillating linear wave is created at the left boundary, and the octagonal region has a refractive index of 2, which occurs in certain crystals such as boron nitride.
The video has two parts, showing the energy density of the wave averaged in two different ways:
Sliding average: 0:00
Average from the beginning: 1:40
In the first part, the average is taken over a sliding time window. In the second part, the average is taken from the beginning of the simulation. The boundary conditions are absorbing on the right boundary, and periodic between the top and bottom boundary. The graph at the right shows the wave energy near the right boundary of the simulation, slightly averaged over a moving time window.

Render time: 40 minutes 45 seconds
Compression: crf 23
Color scheme: Inferno by Nathaniel J. Smith and Stefan van der Walt
https://github.com/BIDS/colormap

Music: "Last Sunrise" by Adam MacDougall‪@AdamMacDougall-q2d‬

See also
https://images.math.cnrs.fr/des-ondes... for more explanations (in French) on a few previous simulations of wave equations.

The simulation solves the wave equation by discretization. The algorithm is adapted from the paper https://hplgit.github.io/fdm-book/doc...
C code: https://github.com/nilsberglund-orlea...
https://www.idpoisson.fr/berglund/sof...
Many thanks to Marco Mancini and Julian Kauth for helping me to accelerate my code!

#wave #refraction #prism #octagon