NUMERICAL SIMULATION OF COHERENT STRUCTURES IN AXIAL FLOW THROUGH A RECTANGULAR CHANNEL CONTAINING A CYLINDRICAL ROD

摘要

Exploratory RANS and LES computations of turbulent flow in a rectangular channel containing a single cylindrical rod have been performed, with particular interest in the flow structure near the gap between the rod and the channel wall. The Reynolds number for the channel flow was 108,000, The computations document the formation of a sequence of large-scale, quasi-periodic pairs of counter-rotating vortices that dominate the flow in the gap region and whose effects extend far beyond the gap region. The unsteady RANS computations predict a transient state of such structures giving way to steady axial flow, while the LES computations reproduce a continuing sequence of similar structures. The simulations are compared to recent experimental results in the same configuration.