NON-NEWTONIAN FLOW OVER AN ASYMMETRICAL CONFINED CIRCULAR CYLINDER IN A CHANNEL

Abstract

Momentum and heat transfer across an asymmetrically confined long circular cylinder in a plane channel is numerically investigated for the range of Reynolds numbers 1< Re<40 and gap ratio of 7=0.375, y=1, for a fixed blockage ratio of P=0.5.The values of the Prandtl number are taken as Pr=1 and Pr=50. The non- Newtonian type of power law fluids are studied with the range of power law index as 0.4<n<1.8. Flow and thermal patterns are analyzed so as to study the effects variation of Re, Pr, n, y on kinematics of flow and heat transfer. Wake size is observed to increase as Re is increased, keeping n constant whereas it decreases as n increases. It is also found out that when cylinder is asymmetrically placed, the flow separation is delayed and thus wake formation starts at a higher Re as compared to symmetrical placement. Drag is found to decrease with increasing Re values at constant n, while it increases as we move from shear thinning (n<1) to Newtonian (n=1) and then to shear thickening (n>1) fluids, Re remaining constant. It is observed that asymmetrical placement leads to a drastic reduction in overall drag values. Nusselt number is higher for symmetrical placement of cylinder as compared to asymmetrical one.