A theoretical study of the turbulent diffusion in incompressible shear flows and in passive scalars

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Abstract

The triple velocity, the pressure-velocity, and the scalar-scalar-velocity correlations in incompressible turbulent shear flows and in passive scalar fields are studied by using the two-scale direct-interaction approximation, which satisfies the solenoidal condition of the velocity fields and systematically introduces the cutoff wave numbers. As a result, we obtain their expressions of the gradient diffusion type involving the effect of cross-diffusion. The model constants in the obtained expressions for the triple velocity and the pressure - velocity correlations are close to the values used in the turbulence models. The derived expression for the scalar-scalar-velocity correlation shows the complex dependence on the ratio R of the velocity length scale to the scalar one. As a special case of R= 1, we obtain its explicit expression whose model constant also agrees well with the numerically optimized value.

Original languageEnglish
Pages (from-to)2636-2646
Number of pages11
JournalPhysics of Fluids
Volume10
Issue number10
DOIs
Publication statusPublished - 1998 Jan 1

ASJC Scopus subject areas

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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