Here’s a little demo on “sculpting” initial velocities for thinking particles. (I am sure this can also be done with Dynamics). With this technique one can have full control over how particles will behave for example in an explosion. All you have to do is to block out the rough shape of your particle explosion, the rest is some vector math and a little bit of xpresso magic ;-) The original concept for this comes from Hristo Velev, who is a Thinking Particles Meister. You can find the 3D Max TP Tutorial from Hristo here:
I can highly recommend to watch the tutorial and then try it out yourself, it’s basic usage of the Ray Collision Node. Hristo is also very good in explaining what’s going on here. (Hristo has two Thinking Particle Tutorial DVD’s out, which are unfortunately for TP in 3D Max, but as you can see in this example, transferring the concepts into C4D isn’t that hard.) (no audio)