It's kind of late, since the result came this Monday, but I want to notify that my proposal was accepted for this year Google Summer of Code! :D
Krita have a lot of awesome brushes, whose is fun to play with (checkout this KDE forum thread to see the works that artists have done using it), so I wanted to do something that could be a nice new feature. Then, I proposed a sandpainting brush for Krita.
After I saw some videos of this type of art, I was a bit lost of how I could accomplish such a beautiful effect on a canvas. I searched through the web about similar effects and particle system in game engines is the closest concept. However, most particle systems do not deal with the singularities of granular particle system. Sometimes sand acts like fluids and sometimes acts like a deformable solid. So sand simulation it's not very similar to particle systems used to simulate fluids like water.
But eventually, I found the exact concept that I was looking for : computational granular dynamics, used in the simulations and predictions of avalanches, land slides and general powder technology. So, after some papers and books chapters I got the idea to develop the project: simulate sand particles usind a discrete element modelling based particle layer. It's not a easy task, since the real time aspect of the sand spreading movement it's crucial, but I believe that with some problem relaxations I could make this work in the due time. :)
Soon enough I will show some results in simulations that I've been doing. Not much visual results but it's something.
Until next time!