Particulate Flow Simulation

The pettern formation in a rotating suspension of 160 settling balls in a horizontal cylinder: Angular speed is 12

A rotating suspension of 160 settling balls in a horizontal cylinder filled fully with
an incompressible viscous Newtonian fluid for 65 < t < 75: Six clusters are forming.

The whole cylinder is rotating with angular speed equal to 12.
The length of the cylinder is 8 and its diameter is 1.
The central axis of the cylinder is horizontal and its two ends are closed.
The dimension of computational domain = (0,1+4h)x(0,8)x(0,1+4h).
The initial position and the velocity field are from the results of angular speed equal to 8 at t=30.
The diameter of balls = 0.15.
The solid fraction is 2.53125%.
The density of tha ball = 1.25
The density of fluid = 1
The viscosity = 0.15
The mesh size for the velocity field = 1/64.
The mesh size for the pressure = 1/32.
The time step=0.001.
The averaged ball speed for the last second = 4.4385 (the particle Re= 4.4385).