Paper/Presentation Title

Distributed Moments of a Scalar PDF

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.

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Jul 1st, 12:00 AM

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.