transient simulation of mixing tank
 

Hi

I am simulating a mixing tank with 300 RPM.In my model we have two misible species are assumed completely separate at starting i.e. toluene in top layer and styrene in bottom layer at the start in the tank.I want to know what should be ideal time step. With time less then 0.1 sec computational time is too high. If i take 1 sec time step then scaled residual is not folling below 10-3 for continuity.

Can u suggest about judging convergence? Should i consider monitoring other parameter and should i ignore residual?

will parallel processsing be useful for transient simulation? I have 97000 cells in my geometry?