i am doing this fluid simulation that just hit some coke cans, since they are RBD so the liquid move them, is there a way to make them start the simulation when the particles of the liquid hit them?

i know that i can animate the active switch 0 off 1 on, and do it by hand, but is there a node that can trigger the event?

i don't want to wast time calculating a coke can just sitting in the floor waiting.

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=17191 [sidefx.com]


also is there a way to kill the particles that are alone? for the particles that fall to the ground i can put a grid and make it a sink, but if a particle is alone for long time can i kill it? (there is a daemon to kill this stuff in real flow, not sure if there is a node in Houdini or i have to do a magic expression to do that?) thanks .