The Integrate operator allows you to immediately integrate particle velocities into particle positions.
Integrate velocity: adds the velocity of the particle to the position of the particle.
Do nothing: no integration action will be taken.
Keep velocity: after the velocity is integrated, the velocity is left unchanged.
Clear velocity: after the velocity is integrated, the velocity is cleared (set to zero).
Flag as already integrated: after the velocity is integrated, the velocity is left unchanged but also flagged internally as already integrated, so that it won’t be re-integrated at the end of the time step.