A study of the closure problem for pressurescalar covariances
Abstract
Perhaps the most commonly used closure for the pressurecorrelation terms in secondorder closure models is Rotta's returntoisotropy parameterization, which was originally developed for shear flows. It is not clear that it alone is adequate for application to convective turbulence, however, because of the pervasive effects of buoyancy on turbulence structure. This closure problem is studied for the pressurescalar term in the scalar flux equation with a data set generated through largeeddy simulation (LES) of a convective boundary layer. The pressure field is resolved into turbulenceturbulence, meanshear, buoyancy, Coriolis force, and subgridscale components, and it is found that the buoyancy and turbulenceturbulence components dominate. The buoyancy contribution to the pressuregradient/scalar covariance is onehalf of the buoyancy production term in the flux equation, to a good approximation, while the turbulenceturbulence contribution can be parameterized adequately with Rotta's returntoisotropy assumption.
 Publication:

5th Symposium on Turbulent Shear Flows
 Pub Date:
 1985
 Bibcode:
 1985stsf.proc...12M
 Keywords:

 Atmospheric Models;
 Covariance;
 Fluid Pressure;
 Planetary Boundary Layer;
 Buoyancy;
 Coriolis Effect;
 Equations Of Motion;
 Incompressible Fluids;
 Isotropic Turbulence;
 Pressure Distribution;
 Scalars;
 Turbulent Flow;
 Fluid Mechanics and Heat Transfer