Reno Genest
Ansys Employee

Hello Weidong,

There is an example of a sphere dropped in water here:

It is not DEM, but if you have only one sphere, you could mesh the sphere with regular elements and have the sphere rigid:

You will find papers here:

You can search for more papers on website.

Also, DEM particles can be coupled with the iCFD (incompressible CFD) solver in LS-DYNA: