title: Lattice-Boltzmann
abstract: Trying to put shapes in a wind-tunnel but they keep exploding.
keywords: blimp,programming
date: 02/03/2026

![image](/lbm/screen.png "The blimp tool GUI including LBM.")

<iframe src="https://www.youtube.com/embed/C6d2B1k8jJo?si=9oRAeRx1VnD57Y1S" frameborder="0" allowfullscreen></iframe>

<iframe src="https://www.youtube.com/embed/73NPtT4O-Rk?si=Y9tHdqAHSIdVsDoW" frameborder="0" allowfullscreen></iframe>

This issue in-particular was because I had misimplemented the diagonal bounce in the algoritim.  The simulator will still do this, particularly when the grid size is very small. I assume it has something to do with the speed of sound. I have validated that it is not to do with my implementation by running it under the same conditions as [this page](https://vanhunteradams.com/DE1/Lattice_Boltzmann/Lattice_Boltzmann.html) which was very helpful for understading LBM.

This was implemented as part of the [blimp tool](https://github.com/w-greenwood/blimp) and is part of a blimp series of posts!

- [Unwrapping the Blimp](/unwrap)