Velocity Weight

When using particles as emitters, the particles can drag the fluid along their trajectory as they move. The larger this value, the more the particles will affect the fluid velocity.

: Note that vice versa, you can also let the fluid drag along the particles by using the Particle Velocity Scale parameter (see Velocity).

Normal Force

The force that the object exerts on the fluid into direction of it's surface normal. Normal Force requires more simulation time than the Direction Force below. It should be preferred for planar emitters that have the same normal everywhere like a plane or disc.

Directional Force

Emit a force that points into the direction specified here. While the Normal Force may change it's direction across the emitter's surface, the Directional Force is not affected by the emitter's surface normals.


Pressure can make the fluid expand or contract as it would in an explosion or black hole. Positive values cause expansion, negative values cause contraction.