Large Eddy Simulation of Turbulent Heat Transfer in Curved Pipe Flow

Abstract

In the present investigation, turbulent heat transfer in fully developed curvedpipe flow has been studied by using large eddy simulation (LES). We consider a fully developed turbulent curvedpipe flow with axially uniform wall heat flux. The friction Reynolds number under consideration is Reد„  = 1000 based on the mean friction velocity and the pipe radius, and the Prandtl number (Pr) is 0.71. To investigate the effects of wall curvature on turbulent flow and heat transfer, we varied the nondimensionalized curvature (خ´) from 0.01 to 0.1. Dynamic subgridscale models for turbulent subgridscale stresses and heat fluxes were employed to close the governing equations. To elucidate the secondary flow structures due to the pipe curvature and their effect on the heat transfer, the mean quantities and various turbulence statistics of the flow and temperature fields are presented, and compared with those of the straightpipe flow. The friction factor and the mean Nusselt number computed in the present study are in good agreement with the experimental results currently available in the literature. We also present turbulence intensities, skewness and flatness factors of temperature fluctuations, and crosscorrelations of velocity and temperature fluctuations. In addition, we report the results of an octant analysis to clarify the correlation between nearwall turbulence structures and temperature fluctuation in the vicinity of the pipe wall. Based on our results, we attempt to clarify the effects of the pipe curvature on turbulent heat transfer. Our LES provides researchers and engineers with useful data to understand the heattransfer mechanisms in turbulent curvedpipe flow, which has numerous applications in engineering.