Keywords
turbulent diffusion, grid turbulence, expected mass fraction, planar laser induced fluorescence (plif), particle image velocimetry (piv)
Start Date
1-7-2010 12:00 AM
Abstract
The evolution of concentration values in a turbulent flow is quantified by theprobability density function (PDF) of concentration or more simply by the expected massfraction function (EMF). It is convenient to use some lower-order moments to approximatethe PDF or EMF. In this paper a particularly simple representation of these moments isexplored. Concentration measurements using planar laser induced fluorescence (PLIF) aremade over the cross-section of a fluorescent plume emanating from a point source in a gridturbulenceflow in a water tunnel. It is observed that the distributed moments across theplume are determined from a ‘local’ concentration scale and the mean concentrationprofile. The moments of the EMF appear to be related to the center-line moments and theEMF to have a simple, self-similar form when scaled with the center-line meanconcentration.
Distributed Moments of a Scalar PDF
The evolution of concentration values in a turbulent flow is quantified by theprobability density function (PDF) of concentration or more simply by the expected massfraction function (EMF). It is convenient to use some lower-order moments to approximatethe PDF or EMF. In this paper a particularly simple representation of these moments isexplored. Concentration measurements using planar laser induced fluorescence (PLIF) aremade over the cross-section of a fluorescent plume emanating from a point source in a gridturbulenceflow in a water tunnel. It is observed that the distributed moments across theplume are determined from a ‘local’ concentration scale and the mean concentrationprofile. The moments of the EMF appear to be related to the center-line moments and theEMF to have a simple, self-similar form when scaled with the center-line meanconcentration.
