Global ETD Search
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Showing 1 to 13 of 13 for “"stratified turbulence"”.
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Differential Diffusion of Scalars in Sheared, Stratified Turbulence
… density interface compared to salt for strongly stratified, weakly turbulent flows. In the presence of differential diffusion, buoyancy flux and mixing efficiency at the interface are functions the density ratio and entrainment laws for a two scalar flow exhibiting differential diffusion agree …
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On the passive oscillations of a splitter plate in stratified turbulence
… experiments were conducted to understand the turbulence-induced motions of a rigid at plate able to rotate at its quarter span. Dominant coherent motions that varied along the vertical direction were imposed on the incoming flow using a variety of tapered cylinders. Emphasis is placed on the …
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Variational multiscale method for coupled systems: free-surface flows and stratified turbulence
… flows with a sharp interface marker and stratified turbulence with a smooth temperature field. The additional nonlinearity introduced by the active scalar field to the nonlinear Navier-Stokes equation system is effectively accounted for by variationally derived stabilization term. In the …
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Dynamics and parameterization of stably stratified turbulence: implications for estimates of mixing in geophysical flows
… observed length scales of overturns in stably-stratified shear-flow turbulence and the fundamental length scales constructed from dimensional analysis of basic physical quantities. In geophysical flows such as the ocean, overturns are relatively easy to observe while the basic quantities are …
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Dynamically induced uncertainty in stratified turbulent mixing models
The interaction of turbulence with buoyancy effects due to gravity is of central importance in a wide range of environmental and industrial flows. On both global and regional scales in the ocean, it is necessary to model small-scale turbulent processes and the way in which they enhance mixing in …
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Study of the role of differential diffusion and equation of state on the features of stably stratified turbulent channel flow using direct numerical simulations
Stably stratified turbulent flows are observed in many systems, ranging from engineering applications to environmental flows. The density variation in such flows, particularly that observed in water bodies depends on temperature and salinity (salt content) through an equation of state (EoS). The …
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Mixing in stably stratified turbulent flows: improved parameterizations of diapycnal mixing in oceanic flows
… stable density interface, due to background turbulence is an ubiquitous phenomenon in both natural and engineered flows. Fundamental understanding and quantitative prediction of turbulent mixing in stratified flows is a challenging problem, with a broad range of applications including (but …
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The Dynamics of Geophysical and Astrophysical Turbulence
Turbulence is ubiquitous within geophysical and astrophysical fluid flows. Its interaction with physical ingredients such as rotation and stratification gives rise to spectacular dynamics, including the layering of material properties, which in turn influence the transport and distribution of heat, …
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Un-mixing the Ocean: Double Diffusion and Turbulence in Polar Oceans
… interaction of double diffusive convection with turbulence forced at a prescribed rate. Utilising the theory developed in chapter 1, the transition between double diffusive convection and stratified turbulence is identified and a criterion is developed for that transition in terms of profiles in …
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On vortex rings impacting a sharply-stratified interface
… the dynamics of vortex rings impacting a sharply-stratified density interface. This problem has a long history and is important for understanding how individual eddies in stratified turbulence mix the density field. We tackle this problem using a combination of experimental, numerical and …
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Energetics and mixing in stratified turbulent flows
… the upwelling of water through the stably stratified ocean interior, needed to close the global circulation, is only possible through the enhanced vertical mixing resulting from turbulence. The transport of heat, carbon and nutrients is also affected by this mixing. Understanding its …
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Waves and turbulence in sustained stratified shear flows
The speed and efficiency of stratified turbulent mixing in homogenising temperatures, chemical composition and flow speeds makes it one of farthest reaching fluid mechanical phenomenon for life on earth. It is an aesthetically beautiful phenomenon, rich in complex physical behaviours and extremely …
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Anisotropic Turbulence Models for Wakes in an Active Ocean Environment
A set of second-moment closure turbulence models are implemented for the study of wake evolution in an oceanic environment. The effects of density stratification are considered, and the models are validated against laboratory experiments mimicking the stratified ocean environment, and against …