Working on a sand simulation for the spider and encountered something very new in Houdini (for me). Did you know the SOP Solver is actually a DOP Network in disguise, and you can not only dive into it, but there are also way more settings you need to know about than the usual Solver workflow suggests?
Like, interpolation of values can go terribly wrong, looking good on whole frames 1, 2, 3, but going crazy on fractional frames.
The workaround is to "Allow Editing" on your Solver, dive into it (there is a hole new world), select the DOP and uncheck "Interpolate Display Data" there.
Soooo.... intuitive...