Steady flow of power-law fluids across a circular rotating cylinder

The flow of a non -Newtonian, power-law fluid, directed normally to a horizontal circular, rotating cylinder is considered in the present paper. The problem is investigated numerically with a finite volume method using the commercial code ANSYS FLUENT with a very large calculation domain in order that the flow could be considered unbounded. The investigation covers the power-law index from 0.1 up to 2, the Reynolds number range from 0.001 up to 40 and the dimensionless rotation rate from 0 up to 10. Lift and drag forces have been calculated for many combinations of the above three parameters. The results are quite different at low and high Re, at low and high rotation and in shear-thinning and shear-thickening fluids. However, it is found that negative values of drag coefficient appear in Newtonian, mildly shear thinning fluids and shear-thickening fluids but never in pure shear-thinning fluids and that for all kinds of fluids the lift coefficient increases (either linearly or nonlinearly) with increasing rotation.