Local anisotropy in heated and cooled turbulent boundary layers

Abstract

Turbulent temperature as well as streamwise and vertical velocity components have been measured in relatively high Reynolds number (Rλ∼1100) heated and cooled boundary layers of the Air–Sea Interaction Simulation Tunnel at the Institut de Mécanique Statistique de la Turbulence. Spectra and probability distributions are compared with various consequences of Kolmogoroff’s assumption of local isotropy. The spectral functions present a first approximation agreement with the assumption. Yet, evidence of local anisotropy is shown by the values of the skewness of ∂T/∂x1 which are very different from zero, either positive or negative. Possible errors due to cold wire velocity sensitivity are examined. An apparent connection between small scale and large scale anisotropy is discussed.