Dynamics and parameterization of stably stratified turbulence: Implications for estimates of mixing in geophysical flows

• Main Author: Mater, Benjamin D
• Format: Dissertation
• Language: English
• Subjects: civil engineering; geophysics; physical oceanography
• ISBN: 9781321168365; 1321168365

This research focuses on the relationship between the 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 not. As such, overturns provide a means of inferring basic quantities if the relationship between the observed and fundamental scales are known. In turn, inferred values of the basic quantities, namely the turbulent kinetic energy k, and the dissipation rate of turbulent kinetic energy epsilon, can be used to estimate diapycnal diffusivity (i.e. turbulent mixing). Most commonly, the observed Thorpe length scale, LT, is assumed to scale linearly with the fundamental Ozmidov scale, LO=(epsilon/N 3) 1/2, so that inferred values of epsilon can be obtained and used to estimate mixing from the Osborn formulation for diapycnal diffusivity. A major goal of this research is to re-examine this and other possible scalings using dimensional analysis, direct numerical simulation (DNS), laboratory data, and field observations. (Abstract shortened by UMI.).