Working on a river-like flip-fluid sim cached to disk.

I’m reading the sim back into Houdini and extracting a few points based on their ID numbers.
The idea is to copy geometry onto these points and match the flip-fluid motion and collisions.

I assumed the ID’d points would remain visible until being killed at a simulation “limit”, but many of the ID’d points are disappearing before hitting that limit.

I believe this is caused by the “reseeding” which will… “Create new particles in voxels where the particle count has dropped too low to properly represent the fluid surface, and delete particles in voxels that have become too crowded.”

Have tried turning off reseeding, but the results haven’t been acceptable.

Am now using an Attribute Transfer SOP (in a Solver SOP) to transfer the velocity from the points in the cached sim to the selected points, and updating their positions that way. It’s sort of working but seems way too “hacky”.

Any suggestions for a better work-flow?

Cheers.

If you can't turn off reseeding which can also happen if you need your sim to be narrow band, then you can instead of transferring the v form points, save vel field from sim itself and then advect some points using it

Or you can create separate object or just data containing your points and advect them using vel field within the original flipsim, then you don't have to same the vel field, just those points as a separate group or something