J. zyxwvutsrqpon Fluid Mech. zyxwvutsrqp (1993), zyxwvuts 001. 256, pp. 163-197 Copyright zyxwvutsrq 0 1993 Cambridge University Press zyxwvuts 163 Direct simulations of low-Reynolds-number turbulent flow in a rotating channel By REIDAR KRISTOFFERSENJ- AND HELGE I. ANDERSSON Department of Applied Mechanics, Faculty of Mechanical Engineering, The Norwegian Institute of Technology, N-7034 Trondheim, Norway (Received 20 September 1991 and in revised form 14 May 1993) Direct numerical simulations of fully developed pressure-driven turbulent flow in a rotating channel have been performed. The unsteady Navier-Stokes equations were written for flow in a constantly rotating frame of reference and solved numerically by means of a finite-difference technique on a 128 zyxw x 128 x 128 computational mesh. The Reynolds number, based on the bulk mean velocity Urn and the channel half-width h, was about 2900, while the rotation number Ro = 2 1521 h/Um varied from 0 to 0.5. Without system rotation, results of the simulation were in good agreement with the accurate reference simulation of Kim, Moin & Moser (1987) and available experimental data. The simulated flow fields subject to rotation revealed fascinating effects exerted by the Coriolis force on channel flow turbulence. With weak rotation (Ro = 0.01) the turbulence statistics across the channel varied only slightly compared with the non- rotating case, and opposite effects were observed near the pressure and suction sides of the channel. With increasing rotation the augmentation and damping of the turbulence along the pressure and suction sides, respectively, became more significant, resulting in highly asymmetric profiles of mean velocity and turbulent Reynolds stresses. In accordance with the experimental observations of Johnston, Halleen & Lezius (1972), the mean velocity profile exhibited an appreciable region with slope 252. At Ro = 0.50 the Reynolds stresses vanished in the vicinity of the stabilized side, and the nearly complete suppression of the turbulent agitation was confirmed by marker particle trackings and two-point velocity correlations. Rotational-induced Taylor-Gortler-like counter-rotating streamwise vortices have been identified, and the simulations suggest that the vortices are shifted slightly towards the pressure side with increasing rotation rates, and the number of vortex pairs therefore tend to increase with Ro. 1. Introduction Turbulent flows in rotating reference frames are of considerable interest in a variety of industrial, geophysical and astrophysical applications. Fluid motions at large scales on a planet as well as the flow in rotating machinery are largely affected by system rotation. The fluid motions are turbulent in the majority of practical cases (e.g. natural flows like ocean currents, estuaries and atmospheric boundary layers, and engineering flows in rotating devices such as turbines, pumps, compressors and cyclone separators), and it is well known that system rotation affects both the mean motion and the turbulence structure. Striking examples of the many fascinating rotational-induced flow phenomena have been reviewed by Tritton (1978, 1985) and Hopfinger (1989). Recent advances in the field are summarized in the report on the Euromech colloquium on the effect of background rotation on fluid motions (Hopfinger & Linden 1990). t Also : ERCOFTAC Pilot Centre, EPFL-Ecublens, CH-1015 Lausanne, Switzerland.