Lattice Boltzmann Method

Measures the flow on screen: the low end goes just above the free stream and its ripples, so undisturbed air takes the ramp's darkest colour; the high end goes to the strongest flow, so what the body does uses the whole ramp. For a glowing wake use Flow Speed with Frame on Ground. The range resets when the field or the frame changes.

Layers stack on the field in this order. Each has its own opacity and density.

The watermark becomes a solid wall in the flow.

Opaque pixels become solid. Drag a picture to move it.