On the Velocity Gradient in Stably Stratified Sheared Flows. Part 1: Asymptotic Analysis and Applications
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We give a new derivation of the familiar linear relation for the dimensionless velocity gradient in the stably stratified surface layer and provide physical and empirical grounds for its universal applicability in stationary homogeneous turbulence over the whole range of static stabilities from Ri = 0 to very large Ri. Combining this relation with the budget equation for the turbulent kinetic energy we obtain the “equilibrium formulation” of the turbulent dissipation length scale, and recommend it for use in turbulence closure models.
KeywordsFlux Richardson number Stationary and homogeneous regime Strong static stability Turbulence closure Turbulent dissipation length scale Turbulent kinetic energy Velocity gradient
This work has been supported by the EC FP7 projects ERC PBL-PMES (No. 227915) and MEGAPOLI (No. 212520); and the Norwegian Research Council project 191516/V30 Planetary Boundary Layer Feedback in the Earth’s Climate System.
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