I'm looking for a way to simulate a sand castle disintegrating like semi-dank sand after it gets hit from a jet of water. How would you simulate disintegrating sand in Houdini?

You will probably want to combine a deforming model with a procedural sand shader on it with another simple particle system with “slide on surface” particles.

I would use point colours to drive the model deformation. That way you can spray particles onto your geo, turn that into point colours, then using a VEX SOP that uses Cd as a mix, blend between positions. Further non-linear looking blending could then be done by using Cd.r/g/b differently to blend at different times/speeds.

Sean

You could use the SOP_Solver_DOP to create a feedback loop to simulate the ‘melting’ type motion of the sand as it disintergrates. I know it doesn't actually melt but its a similar movement….