Large Eddy Simulation of Turbulent Heat Transfer in a Channel with a Rectangular Cylinder

초록

Periodic vortex shedding from a cylindrical object immersed in cross-flow has been one of the classical research subjects for decades, because it induces periodic force loading on the object, which could significantly damage the cylindrical structure. On the other hand, the large-scale vortices shed from a cylindrical object as a vortex generator can be used to enhance heat transfer in a heat exchanger. In this study, Large-Eddy Simulation of turbulent heat transfer in channel flow with a rectangular cylinder at Re=3000 (based on uniform inlet velocity and cylinder height) and Pr=0.7 was performed with various values of cylinder aspect ratio to identify its effect on the heat transfer characteristics. The blockage ratio is fixed as 0.2. A rectangular cylinder is located on the centerline of the channel flow, generating recirculation bubbles and Karman vortices. The separation points are fixed at the leading edges of the cylinder. The separated flow may reattach, if the aspect ratio is large, yielding significant changes in heat transfer characteristics. The effect of the cylinder aspect ratio on heat transfer enhancement and the related flow physics are discussed in detail.