Kelvin-Helmholtz instability involve a complex physical problem. This study has permitted a good understanding of instabilities thanks to one example. Therefore it was an adapted complement to the hydrodynamic instabilty lesson. It permitted us to use the software FLUENT in specific conditions.
    After numerous tries, we have succeeded in modelising such an instability with this software. So numerical simmulation is a useful method to study this kind of phenomenum. However, obtained results have to be performed with precautions. Such a phenomena is hard to meet in natural conditions, but by looking at pictures (see Illustrations and references) we can imagine how spectacular it must be.