Friday, September 09, 2005

Making a Splash

I have fallen further behind. Oh well. Bound to happen. But thats not the same as no progress.

After trying to get a good splash effect and noticing that the resultant waves damp down very quickly. I experimented with very low viscosity settings. Unfortunately the particle small scale motion becomes quite random. The normal way of solving this is with XSPH, but i found this did not significantly solve the problem. I will try XSPH tonight some more, but then will look at direct methods at reducing numerical dissipation.

The boundary conditions is still getting constant overhauls. Especially when it comes to interacting rigid body motion. I still do not have a fixed solution for this yet and most likely there will be a plethora of options.

Finally one paper suggested a 10 times speed increase by just rearranging the particles in memory to make better use of the CPU Cache architecture. In java this amounts to recreating objects so that they are next to each other in the memory. On a Intel with a normal JVM I got between 2-4 times speed increase. On the AMD64 (already heaps faster) it slowed it down by 5%. So this optimization will stay on the back burner for a while. At any rate I was a little skeptical of 10 times speed increase.

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