Experimental testing of diffusion models in a manipulated turbulent boundary layer

Abstract

An experimental investigation of the performances of one-point closure turbulent diffusion models is performed in an externally manipulated turbulent boundary layer. Detailed hot wire anemometry measurements are performed on a refined two-dimensional grid, allowing the terms of the transport equations of the turbulent stresses to be calculated. The turbulent diffusion terms as well as the convection, production, and viscous diffusion terms are then directly estimated. The dissipation terms of each Reynolds tensor component are estimated by use of local isotropy hypothesis (e ij = 2/3eδ ij ), e being obtained by balancing the turbulent kinetic energy budget. The pressure-strain terms are then obtained by balancing the u' i u' j equations. The results are presented for a streamwise position located near the manipulator trailing edge (x = 2δ 0 ). All of the measurements are performed at relatively large distances from the wall (y + > 120), allowing the minimization of the spatial integration effects of the probes. The balances show the modifications imposed to the classical turbulent boundary-layer equilibria. Knowledge of the different terms allows several experimental applications of the conventional turbulent diffusion models to be made.