Prashanth
Ansys Employee

Hello Dong,

Here's my two cents on your model. I would expect steel balls dropped over a hard surface to reproduce the same results. The bouncing also looks unphysical even for a hard surface though, but your's a water surface. Note that the balls that you are dropping are point masses that don't displace any water volume. 

You might have to reconsider your model setup even if you are not interested in water pool splash. Instead of DPM or MPM, try using VOF + 6DOF with overset.

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