Statistical Features of Scalar Flux in a High-Schmidt-Number Turbulent Jet

Abstract

In this paper, we investigate the statistical characteristics of the mass flux in an axisymmetric turbulent jet diffusion field of a high-Schmidt-number matter. The diffusing fluid is a dye solution (whose Schmidt number is about 3,800), and the simultaneous measurements of two velocity components and concentration at five different jet Reynolds numbers have been made by a combined probe of a X-type hot-film and a fiber-optic concentration sensor. It is found that the mass flux is hardly affected by the magnitude of Schmidt (or Prandtl) number. The axial velocity-concentration cospectra on the jet centerline show -7/3 scaling law. And their scaling range agree with the overlap range of the inertial subrange and the convective subrange. On the other hand, it seems that the radial velocity-concentration cospectra at some distance off the jet centerline (at r/bU = 0.73) show about -2 scaling law.