Override FLIP velocity field with custom field

[portdusk]

I know this is probably a very straight-forward problem, but I can't seem to wrap my head around it. Any advice or explanations would be greatly appreciated.

I created a custom vector field in DOPs, and I want to take the data from that field and copy it into the vel field in my FLIP fluid object.

The custom field is not the same size/number of divisions as the velocity field. I want to copy the values based on their 3D position in space, so I can't be stretching or distorting the custom field to match the FLIP vel field.

I tried using a gas calculate, with "vel" being my destination field and "RBD_vel" being the source, but all that happens is the visualizations for both disappear in the viewport. Are they being copied, and I'm just not seeing the new visualizations?

If anyone knows how to copy data between fields I would really appreciate some help!

[portdusk]

Well with a little tinkering I found the solution. I simply had the nodes placed in the wrong order, so they weren't being processed correctly by the flip solver.

I reordered my node tree, and now my point velocity from an imported geometry is being transformed into a field and then used to override the FLIP velocity field.

[johner]

Glad you found an answer. Depending on your setup, you possibly could also use the "Pump From Object" shelf tool. This tool uses a FluidSource SOP to create a velocity field from geometry point velocities, then a SourceVolume DOP to bring those velocities into the FLIP simulation, giving you a fair bit of control.

Attached is an example of using a simple POP net to transfer particles velocities to a FLIP tank, all set up with shelf tools. A similar setup should work with Pyro sims as well.

pump_from_particles.hip