The Spectral Velocity Tensor for Homogeneous Boundary-Layer Turbulence

1989 ◽  
pp. 149-193 ◽  
Author(s):  
L. Kristensen ◽  
D. H. Lenschow ◽  
P. Kirkegaard ◽  
M. Courtney
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Turbulence ◽  
Velocity Tensor ◽  
Spectral Velocity

The spectral velocity tensor for homogeneous boundary-layer turbulence

1989 ◽  
Vol 47 (1-4) ◽  
pp. 149-193 ◽  
Author(s):  
L. Kristensen ◽  
D. H. Lenschow ◽  
P. Kirkegaard ◽  
M. Courtney
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Turbulence ◽  
Velocity Tensor ◽  
Spectral Velocity

A spectral model for stably stratified turbulence

2015 ◽  
Vol 781 ◽  
pp. 330-352 ◽  
Author(s):  
Antonio Segalini ◽  
Johan Arnqvist
Keyword(s):  
Boundary Layer ◽  
Initial Time ◽  
Model Parameters ◽  
Stratified Turbulence ◽  
Atmospheric Measurements ◽  
Final State ◽  
Velocity Tensor ◽  
Characteristic Values ◽  
Spectral Velocity ◽  
Breakup Time

A solution of the inviscid rapid distortion equations for a stratified flow with homogeneous shear is proposed, extending the work of Hanazaki & Hunt (J. Fluid Mech., vol. 507, 2004, pp. 1–42) to the two horizontal velocity components. The analytical solution allows for the determination of the spectral tensor evolution at any given time starting from a known initial condition. By following the same approach as that adopted by Mann (J. Fluid Mech., vol. 273, 1994, pp. 141–168), a model for the spectral velocity tensor in the atmospheric boundary layer is obtained, where the spectral tensor, assumed to be isotropic at the initial time, evolves until the breakup time where the spectral tensor is supposed to achieve its final state observed in the boundary layer. The model predictions are compared with atmospheric measurements obtained over a forested area, giving the opportunity to calibrate the model parameters, and further validation is provided by additional low-roughness data. Characteristic values of the model coefficients and their dependence on the Richardson number are proposed and discussed.

The spatial structure of neutral atmospheric surface-layer turbulence

1994 ◽  
Vol 273 ◽  
pp. 141-168 ◽  
Author(s):  
Jakob Mann
Keyword(s):  
Spatial Structure ◽  
Second Order ◽  
Navier Stokes ◽  
Order Structure ◽  
Navier Stokes Equation ◽  
Second Order Statistics ◽  
Boundary Layer Turbulence ◽  
Velocity Tensor ◽  
One Year ◽  
Spectral Velocity

Modelling of the complete second-order structure of homogeneous, neutrally stratified atmospheric boundary-layer turbulence, including spectra of all velocity components and cross-spectra of any combination of velocity components at two arbitrarily chosen points, is attempted. Two models based on Rapid Distortion Theory (RDT) are investigated. Both models assume the velocity profile in the height interval of interest to be approximately linear. The linearized Navier–Stokes equation together with considerations of ‘eddy’ lifetimes are then used to modify the spatial second-order structure of the turbulence. The second model differs from the first by modelling the blocking by the surface in addition to the shear. The resulting models of the spectral velocity tensor contain only three adjustable parameters: a lengthscale describing the size of the largest energy-containing eddies, a non-dimensional number used in the parametrization of ‘eddy’ lifetime, and the third parameter is a measure of the energy dissipation.Two atmospheric experiments, both designed to investigate the spatial structure of turbulence and both running for approximately one year, are used to test and calibrate the models. Even though the approximations leading to the models are very crude they are capable of predicting well the two-point second-order statistics such as cross-spectra, coherences and phases, on the basis of measurements carried out at one point. The two models give very similar predictions, the largest difference being in the coherences involving vertical velocity fluctuations, where the blocking by the surface seems to have a significant effect.

The effect of Reynolds number on boundary layer turbulence

1998 ◽  
Vol 18 (4) ◽  
pp. 341-346 ◽  
Author(s):  
David B. DeGraaff ◽  
Donald R. Webster ◽  
John K. Eaton
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layer Turbulence

Frontogenesis and frontal arrest of a dense filament in the oceanic surface boundary layer

2017 ◽  
Vol 837 ◽  
pp. 341-380 ◽  
Author(s):  
Peter P. Sullivan ◽  
James C. McWilliams
Keyword(s):  
Boundary Layer ◽  
Turbulent Mixing ◽  
Shear Instability ◽  
Upper Ocean ◽  
Surface Boundary ◽  
Horizontal Shear ◽  
Boundary Layer Turbulence ◽  
Filament Axis ◽  
Small Width ◽  
The Cross

The evolution of upper ocean currents involves a set of complex, poorly understood interactions between submesoscale turbulence (e.g. density fronts and filaments and coherent vortices) and smaller-scale boundary-layer turbulence. Here we simulate the lifecycle of a cold (dense) filament undergoing frontogenesis in the presence of turbulence generated by surface stress and/or buoyancy loss. This phenomenon is examined in large-eddy simulations with resolved turbulent motions in large horizontal domains using${\sim}10^{10}$grid points. Steady winds are oriented in directions perpendicular or parallel to the filament axis. Due to turbulent vertical momentum mixing, cold filaments generate a potent two-celled secondary circulation in the cross-filament plane that is frontogenetic, sharpens the cross-filament buoyancy and horizontal velocity gradients and blocks Ekman buoyancy flux across the cold filament core towards the warm filament edge. Within less than a day, the frontogenesis is arrested at a small width,${\approx}100~\text{m}$, primarily by an enhancement of the turbulence through a small submesoscale, horizontal shear instability of the sharpened filament, followed by a subsequent slow decay of the filament by further turbulent mixing. The boundary-layer turbulence is inhomogeneous and non-stationary in relation to the evolving submesoscale currents and density stratification. The occurrence of frontogenesis and arrest are qualitatively similar with varying stress direction or with convective cooling, but the detailed evolution and flow structure differ among the cases. Thus submesoscale filament frontogenesis caused by boundary-layer turbulence, frontal arrest by frontal instability and frontal decay by forward energy cascade, and turbulent mixing are generic processes in the upper ocean.

scholarly journals Boundary layer turbulence and flow structure over a fringing coral reef

2006 ◽  
Vol 51 (5) ◽  
pp. 1956-1968 ◽  
Author(s):  
Matthew A. Reidenbach ◽  
Stephen G. Monismith ◽  
Jeffrey R. Koseff ◽  
Gitai Yahel ◽  
Amatzia Genin
Keyword(s):  
Boundary Layer ◽  
Coral Reef ◽  
Flow Structure ◽  
Boundary Layer Turbulence

Parameterization of Eddy Fluxes near Oceanic Boundaries

2008 ◽  
Vol 21 (12) ◽  
pp. 2770-2789 ◽  
Author(s):  
Raffaele Ferrari ◽  
James C. McWilliams ◽  
Vittorio M. Canuto ◽  
Mikhail Dubovikov
Keyword(s):  
Boundary Layer ◽  
Transition Layer ◽  
General Circulation ◽  
Mesoscale Eddies ◽  
Turbulent Boundary Layers ◽  
Mesoscale Variability ◽  
Transition Layers ◽  
Boundary Layer Turbulence ◽  
Dynamical Coupling ◽  
Eddy Fluxes

Abstract In the stably stratified interior of the ocean, mesoscale eddies transport materials by quasi-adiabatic isopycnal stirring. Resolving or parameterizing these effects is important for modeling the oceanic general circulation and climate. Near the bottom and near the surface, however, microscale boundary layer turbulence overcomes the adiabatic, isopycnal constraints for the mesoscale transport. In this paper a formalism is presented for representing this transition from adiabatic, isopycnally oriented mesoscale fluxes in the interior to the diabatic, along-boundary mesoscale fluxes near the boundaries. A simple parameterization form is proposed that illustrates its consequences in an idealized flow. The transition is not confined to the turbulent boundary layers, but extends into the partially diabatic transition layers on their interiorward edge. A transition layer occurs because of the mesoscale variability in the boundary layer and the associated mesoscale–microscale dynamical coupling.

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