Fluid dynamic and thermal performance of a slotted cylinder at low Reynolds number

Abstract

The fluid dynamic and thermal performance of a circular cylinder with a slot parallel to the flow is numerically investigated. The study utilized the semi-implicit finite volume multi-material algorithm MPM-ICE, a component of the Uintah framework. The normalized slot width s/D ranges from 0.1 - 0.3, introducing an additional heat transfer surface area between ∼ 10 and ∼ 50%, and a mass reduction between ∼ 13 and ∼ 38% in the cylinder. We assumed two-dimensional incompressible flow and simulated a Reynolds number ReD between 100 and 1000. The slotted cylinders are found to have a total drag force reduction up to ∼ 45%, compared to a solid cylinder despite the additional viscous drag force in the slot. Convection heat transfer is enhanced up to ∼ 70%. The slotted cylinder performance index, defined as the ratio of the heat rate to the drag force, increases up to maximum of ∼ 3, indicating better overall thermal fluid performance. An entropy analysis showed the best performance index occurs at the highest ReD. Correlations for drag coefficient and Nusselt number are proposed along with an entropy optimization method.