Modeling rotational effects in eddy-viscosity closures

A new approach to sensitize turbulence closures based on the linear eddy-vi scosity hypothesis to rotational effects is proposed. The principal idea is to 'mimic' the behavior of a second moment closure (SMC) in rotating homog eneous shear flow; depending on the ratio of the mean flow to the imposed r otational time scales, the model should be able to bifurcate between two st able equilibrium solutions. These solutions correspond to exponential or al gebraic time dependent growth or decay of turbulent kinetic energy. This fu ndamental behavior of SMCs is believed to be of importance also in the pred iction of non-equilibrium turbulence. A near-wall turbulence model which is based on the linear eddy-viscosity hypothesis is modified in the present s tudy. Wall proximity effects are modeled by the elliptic relaxation approac h. This closure has been successfully applied in the computation of complex , non-equilibrium flows in inertial frames of reference. The objective of t he: present study is to extend the predictive capability of the model to in clude flows dominated by rotational effects. The new model is calibrated in rotating homogeneous turbulent shear flow and subsequently tested in three different cases characterized by profound effects of system rotation or st reamline curvature. It is able to capture many of the effects due to impose d body forces that the original closure is incapable of. Good agreement is obtained between the present predictions and available experimental and DNS data. (C) 1999 Elsevier Science Inc. All rights reserved.