MEASUREMENTS AND HEAT-FLUX TRANSPORT MODELING IN A HEATED CYLINDER WAKE

Hot-wire measurements of velocity and temperature fluctuations have be en made in the self-preserving turbulent wake region of a heated cylin der. Second order statistics including Reynolds fluxes, <(u(i))over ba r>theta, are determined along with relevant triple correlations appear ing in the Reynolds stress and Reynolds flux transport equations. The primary aim with these measurements is to study different modelling le vels for passive scalar quantities. Models for the pressure scalar-gra dient correlation, appearing in the transport equation of the Reynolds fluxes, are compared to measured data. A significant improvement of t he simplest model, -c(1T)(1/tau)<(u(i))over bar>theta, is achieved by including a model for the rapid term that is linear in the mean veloci ty gradients. The mixed timescale, root<(k theta(2))over bar>/epsilon epsilon(theta), seems to be an appropriate choice for tau. Also models for the triple correlations, <(u(i)u(j)theta)over bar>, are compared with the experiments. (C) 1998 Elsevier Science Inc. All rights reserv ed.