Minimum Element Size in Design Modeler?
 

I'm an undergrad student doing summer research, and trying to model a particle collision between two simple spherical particles. The particles have diameters in the range of 50 - 200 microns. I am trying to run a 2D axisymmetric simulation using Ansys Explicit Dynamics in Workbench 15.0. I can refine the mesh near the contact point using a body sizing mesh with a sphere of influence and the mesh generates just fine (with element sizes of about 1 micron). When the simulation runs though, I immediately get "Zero or negative element volume" errors. If I increase the element size I can get it to run, but I lose the resolution I want to have. I think it might be a precision problem, if the elements are so small that the volume rounds to zero. Is there any way around this? Any help or pointers would be appreciated.