Turbulence Structure in Stably Stratified Open-Channel Flows.

Temperature front formation in stably stratified turbulence

Temperature fronts and associated cliff-ramp structures in stably stratified turbulence are investigated using DNS of the Navier-Stokes equations under the Bousinesq approximation. Vertical profiles of temperature fluctuations show sawtooth wave structures which result in a skewed PDF of the derivative of temperature fluctuation in the z-direction. The mechanisms for generating and maintaining ...

Lagrangian mixing in decaying stably stratified turbulence

Direct numerical simulations are used to study mixing and dispersion in decaying stably stratified turbulence from a Lagrangian perspective. The change in density of fluid particles owing to small-scale mixing is extracted from the simulations to provide insight into the mixing process. These changes are driven by temporally and spatially intermittent events that are strongly suppressed as the ...

2DV Nonlinear k-ε Turbulence Modeling of Stratified Flows

The commonly used linear k-ε turbulence model is shown to be incapable of accurate prediction of turbulent flows, where non-isotropy is dominant. Two examples of non-isotropic flows, which have a wide range of applications in marine waters, are saline water flow and the stratified flows due to temperature gradients. These relate to stratification and consequently, variation of density through...

Large eddy simulation of stably stratified open channel flow

On the turbulent Prandtl number in homogeneous stably stratified turbulence

In this paper, we derive a general relationship for the turbulent Prandtl number Pr t for homogeneous stably stratified turbulence from the turbulent kinetic energy and scalar variance equations. A formulation for the turbulent Prandtl number, Pr t , is developed in terms of a mixing length scale LM and an overturning length scale LE , the ratio of the mechanical (turbulent kinetic energy) deca...