STUDY OF FLOW CHARACTERISTICS OVER HEATED PLAIN AND DUAL-STEP CYLINDERS

This work investigated flow past a dual-step cylinder at different wall temperatures, numerically and experimentally. The numerical work was carried out with the help of the computational fluid dynamics solver, Ansys Fluent. For validation, experiments were performed on a wind tunnel for the circular cylinder with step down (D/d < 1), step up (D/d > 1), and plane cylinder (D/d = 1). The drag coefficient was calculated based on the pressure measurements on peripheral points around all three cylinder cases. The results illustrate that the plain cylinder shows a maximum negative magnitude of pressure coefficient, whereas the step-down cylinder shows a minimum. The primary vortices interact with step-induced vortices clockwise and counterclockwise, producing different wake flow characteristics compared to the plane cylinder. Further, the results suggest that the ability to transfer heat from the cylinder wall to the fluid medium is higher for the cylinder with a diameter ratio of D/d < 1.