FORCED CONVECTION FROM A TRAPEZOIDAL BLUFF BODY

Abstract

Studies of flow over trapezoidal cylinders are of great importance in many engineering applications, such as the design of tower structures, suspension bridges, chimneys, heat exchangers, road vehicles, tall buildings, flow meters etc. Most of the present work on flow over trapezoidal cylinders focused on long term flow development. Few considered using numerical methods in their studies on the early stages of impulsively started flow. The complexity of the early stages of impulsively started fluid flow meant that the accurate numerical computation of the flow field was very demanding. However, the evolution of the flow separation around trapezoidal cylinders at the early stages is very different from the long term wake development. Hence, the study of the flow development characteristics during the early stages of an impulsively started flow are necessary for a better understanding of the build-up of the recirculation zone before the flow burst into smaller Karman type of vortices. First, the convective heat transfer from and to a trapezoidal cylinder is important in many engineering applications. Industrial process in which this phenomenon plays an important role are: design of vortex metre, heat exchangers, cooling of glass, plastics and industrial devices, from turbine blades to electronic circuits, and so on. The unsteady behaviour of the flow close to the surface strongly affects the heat transfer from the cylinder. Flow past bluff bodies is particular matter of concern because of their vast applications in chemical industries and aero dynamics for both steady and unsteady flows. However, very few literatures are available concerning to my problem trapezoidal cylinder. I have studied flow and heat transfer around tapered trapezoidal bluff body in steady and unsteady regime.