How to make a particle slide across a mesh? I was trying to create a tear drop effect and I'm using particle system and dynamic paint for this and the face of my character is a sphere(for now ;) ) and I want the tear drop to generate and slide along a vertex group in the sphere and along with make a trail of tear.The trail thing did appear because of dynamic paint although it appears really weird for now.But my another concern is the particle(supposed tear drop) jumps from the mesh.This is even more vivid when looked from the side.So,what I want is the particle to slide along the vertex group.Can anyone please suggest me about how to achieve this? Thanks in advance.
On the surface you want the drop to stick, enable physics collision. Then increase the stickiness value to keep it on the surface, a value of 1.0 will stop it bouncing off the surface as it hits.

You may also want to increase the friction factor to slow down the particle as it slides along the surface.