Flow disturbances over heated indented surface cylinders arranged in a tandem

Abstract

In this study, the thermo-fluid characteristics of flow over tandem circular cylinders are controlled and investigated at 75 ≤Re≤ 200. An identical diameter is set for both circular cylinders. The flow is controlled by a square indent surface placed on the leading edge of the upstream cylinder. The gap ratio between cylinders is kept constant; however, the location of the groove on the upstream cylinder edge varies between θ = 0 ° and 90 °. Thermo-fluid parameters of flow, such as vortex shedding frequency and Nusselt number, are numerically evaluated. It is demonstrated that the effect of Re on force coefficients and convective heat transfer is greater than the influence of the groove and its location on the leading edge of the cylinder. The alteration of Re leads to a change in the flow regime from reattachment to co-shedding. It is found that the Nusselt numbers of tandem-plain cylinders are higher than those of tandem-grooved cylinders. Besides, the variation of the Nu number of the upstream cylinder is insensitive at small angles of groove location (θ < 45 °). Once θ turns to 90 °, the upstream-indented cylinder triggers somewhat high negative pressure coefficient. This results in a 10% reduction of Nu from the downstream cylinder.