Pressure-driven Flow Instability with Convective Heat Transfer through a Rotating Curved Square Duct with Strong Curvature

Abstract

The present paper investigates pressure-driven flow instability with convective heat transfer through a rotating curved square duct with curvature ratio 0.5. Spectral method is used as a basic tool to solve the system of non-linear partial differential equations. The outer wall of the duct is heated while the inner wall cooled, the top and bottom walls being thermally insulated. The duct is rotated in both the positive and negative direction, and investigated combined effects of centrifugal, Coriolis and buoyancy forces. For positive rotation, the unsteady flow characteristics are investigated for the Taylor number 0≤Tr≤1000, and it is found that the multi-periodic flow turns into chaotic flow through various flow instabilities, if Tr is increased in the positive direction. For negative rotation, however, time-dependent flow behavior is investigated for −500≤Tr<0, and it is found that the multi-periodic flow precisely turns into steady-state flow, if Tr is increased in the negative direction. Streamlines and isotherms are also obtained, and it is found that the unsteady flow consists of asymmetric 2- to 6-vortex solutions. The present study shows that the convection due to the secondary flow, enhanced by the combined action of the centrifugal-Coriolis-buoyancy forces, increases heat transfer significantly from the heated wall to the fluid, and whenever the flow becomes periodic and then chaotic, as Tr increases, the rate of heat transfer increases remarkably.