SUDDEN SPIKE
 

I am working on modelling the hydrodynamics of flow in a stirred tank reactor. The modeled reactor is an axial flow impeller type.

The size of my reactor is 0.3m(H=T) with impeller clearance of 0.1m. I made use of Multiple frame of reference modelling technqiue in which the impeller region is identified as the rotating block and the other part of the tank(baffles & rest)are stationary.I have run simulations with grid of 88,690, 174,000 and 270,000 structured cells.

Above the impeller region just immediately after the interface,i noticed a sudden spike in radial velocity and tangential velocity as i approach the shaft wall. This is really gave me a concern.

Can anyone advise on any clue to correct this abnormality?

Expecting yr reply