These crescent shaped dunes appear on Earth and Mars. The TV program "What on Earth?" showed a magnetic one in Africa, with dark sand, probably of volcanic origin.

A recent paper has the Math, and a good summary:

https://arxiv.org/pdf/cond-mat/0308100.pdf

The cosine bump formula is in Fig. 6, and should be easy to do in nodeeditor.

Now needed is numeric simulation javascript software which outputs to MoI NURBS :-)

- Brian