I am simulating the flow in a stirred bead mill. For the continuous case, I am getting reverse flow for low flow rates. Can this be corrected?

I believe this is dependent on the turbulance parameters that you setup to calculate turbulance at your aboundary conditions. What turbulence approximation are you using?

check whether you have specified the backflow parameters sufficiently, and also the reference conditions.too much of turbulance at low pressure ratios causes rapid reverse flow.