Particulate Flow Simulation

The pattern formation in a rotating suspension of 80 settling balls in a horizontal cylinder: Angular Speed is 8.

The pattern formation in a rotating suspension of 80 settling balls in a horizontal cylinder
filled fully with an incompressible viscous Newtonian fluid for 10 < t < 20: Three clusters are forming.

The length of the cylinder is 4 and its diameter is 1.
The central axis of the cylinder is horizontal and its two ends are closed.
The whole cylinder is rotating with angular speed equal to 8.
The dimension of computational domain = (0,1+4h)x(0,4)x(0,1+4h).
The initial position and the velocity field are from the results of angular speed equal to 4 at t=10.
The diameter of balls = 0.15.
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 19 < t < 20 = 2.327, then the particle Re= 2.327.
The maximal value of averaged 80 ball speed = 3.893.