--- title: "Phoenix FD TP Force operator" canonical: "https://documentation.chaos.com/space/PHX4MAX/124659768/Phoenix%20FD%20TP%20Force%20operator" format: markdown --- This page provides information on the Thinking Particles Phoenix FD Force operator. ## **Overview** --- This Thinking Particles operator affects the movement of particles using the velocity from a Phoenix simulation. It allows you to give your particles an interesting motion pattern to add more variety to your scenes. It requires the simulator's cache to contain the grid **Velocity** channel.  > Macro (ui-text-box) > > When doing Liquid simulations, Phoenix populates the grid **Velocity** channel only for cells / voxels inside the liquid volume - empty (air) voxels contain no velocity information. To generate velocity information for the empty voxels, enable **Simulate Air Effects** under the [Dynamics](https://docs-chaos.atlassian.net/wiki/spaces/PHX4MAX/pages/124628691) rollout of the simulator and re-run the simulation.   ## **Inputs** ---   ## **Parameters** ---