Reynolds Number Dependencies in Boundary Layer Axial Stress and Scalar Variance Transport

Abstract

Boundary layer axial stress, (u2), and scalar variance, (c2), transport were investigated using custom hot-wire/photoionization probes. The probes allow instantaneous measurement of all the terms in the evolution equations for (u2) and (c2), excluding molecular diffusion and pressure-strain. Of particular interest are the dominant length scales participating in the transport. Turbulent transport in the wall normal direction was found to prevail over other terms in the evolution equations. Independent of Reynolds number, the peak in the spectra of the turbulent transport term was found to occur near λu, the Taylor microscale associated with u.