Large eddy simulation of turbulent heat transfer in a rotating square duct

摘要

Large eddy simulations of turbulent mixed convection heat transfer in a variable-property thermally developing rotating square duct are presented. A finite volume lower-upper symmetric Gauss-Seidel (LU-SGS) scheme coupled with time derivative preconditioning is used to simulate low Mach number compressible three-dimensional turbulent flow. A localized dynamic subgrid-scale (SGS) model is used to evaluate the unresolved stresses. Characteristic outflow conditions are employed so that the flow can develop further as it responds to the heating as well as rotating conditions. Several isothermal rotating duct cases were calculated and compared with previous DNS results to validate the numerical procedure. Then heated rotating ducts under constant wall heat flux are simulated. The wall heat flux is strong enough to cause the flow to separate in the outward mixed convections. A vanishing inviscid flux derivative method is designed to overcome the difficulty caused by the velocity reversal at the duct outlet when the flow separates. The Reynolds number varies from 4500 to 10,000; The rotation number changes from 0.0133 to 0.176; The Grashof number ranges from -2.2 x 10~6 to 2.2 x 10~6. Simulation of forced and mixed convection cases shows that the flow is strongly influenced by the Coriolis and centrifugal buoyancy forces through complex and delicate mechanisms.