Thank you sir ,

Very nicely explained. If some particles released from a nozzle at some velocity and particles travels (small distance) to strike on a plate at different strike angles  then which velocity is suitable for this case. I am using T=0 Velocity format (case 1) , What is your recommendation.  

I have one more question to you that how to calculate the mass of a plate if there is some erosion (some element loss) . I am using "massall" expression but result is not satisfactory because mass shown in geometry and mass calculated through massall expression are not matched even there is no element loss or erosion.

Thanking You