Quick and dirty Rayleigh-Taylor instability

The Rayleigh-Taylor instability is a well-known benchmarck for CFD codes. The idea is to start with two phases, on on top of the other, the lighter one being underneath. The interface is slightly perturbed, and this plume appears. I describe a quick and dirty way of getting this instability.

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Natural coordinates

natural

Here is an interesting application of Voronoi tesselations / Delaunay triangulations (see previous post The alpha shapes for another one.) Suppose you have a set of points carrying some information, let’s call them particles; the simplest case is just a scalar number representing some field whose value is only known for the particles. Then, you want to compute the value of the field in some other, arbitrary point. (In the simplest instance, you may want to plot the field, and you need to know the values at nodes of a grid.) Continue reading