3ds Max: Particle Swirling?

I'm trying to work out a way of localising a particle swirl effect with a space warp in a PCloud. Basically I'm trying to create a PCloud box and swirl the inner particles and leave the outer particles doing whatever.


I've tried using a Vortex and a Motor. The vortex was great except it didn't have a range limit on the length of the vortex. The Motor was better because it had a limited effect range, but both of them created holes in the particle systems after they had done their thing.


Is there any way to give the particles air resistance, so that when eg. wind blows the particles for 5 frames, the particles decelerate to their original speed?


Thanks

You can use particle flow for these kind of effects.