I'm simulating a hypervelocity impact using SPH. I am using a particle size of 0.1mm with only 3512 SPH particles.

My end time is 1.0 ms. Up until about 1.00 E-01 ms the simulation runs quite quickly (roughly 1-2hrs), but then slows down drastically and takes a couple of days to reach the end time of 1.0ms. There are very few SPH particles so why is it taking so long?

I haven't changed any of the timestep options.

hanks :)