Gradient transport theory

From Glossary of Meteorology

gradient transport theory

A first-order turbulence closure approximation that assumes that turbulent fluxes of any variable flow down the local gradient of that mean variable; analogous to molecular transport.

This local turbulence closure approach assumes that turbulence consists of only small eddies, causing diffusion-like transport. An example is
where the vertical kinematic flux
of a pollutant is modeled as being equal to an eddy thermal diffusivity K times the vertical gradient of mean concentration
. This theory is
also called K- theory or eddy-viscosity theory.
Compare higher-order closure, nonlocal closure, transilient turbulence theory.

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