We present the results of a derivation of the fluctuation energy transport matrix for the two-field Hasegawa-Wakatani model of drift wave turbulence. The energy transport matrix is derived from a two-scale direct interaction approximation assuming weak turbulence. We examine different classes of triad interactions and show that radially extended eddies, as occurs in penetrative convection, are ...

Using high-resolution direct numerical simulation and arguments based on the kinetic energy flux Π(u), we demonstrate that, for stably stratified flows, the kinetic energy spectrum E(u)(k)∼k(-11/5), the potential energy spectrum E(θ)(k)∼k(-7/5), and Π(u)(k)∼k(-4/5) are consistent with the Bolgiano-Obukhov scaling. This scaling arises due to the conversion of kinetic energy to the potential ener...

In this work, we numerically study decaying isotropic turbulence in periodic cubes with frame rotation using the lattice Boltzmann method (LBM) and present the results of rotation effects on turbulence. The implementation of LBM is on a GPU (Graphic Processing Unit) platform using CUDA (Compute Unified Device Architecture). Through the accelerated GPU-LBM simulation, we look into various effect...

We examine mixed-layer deepening and the generation of internal waves in stratified fluid resulting from turbulence that develops in response to an applied surface stress. In laboratory experiments the stress is applied over the breadth of a finite-length tank by a moving roughened conveyor belt. The turbulence in the shear layer is characterized using particle image velocimetry to measure the ...

We have constructed models for the sun at three stages of its evolution: a zero-age main sequence model, the present sun, and a subgiant model. For each model, the turbulent pressure and turbulent kinetic energy were calculated from 3-d radiative hydrodynamical simulations (described in the poster by Robinson et al.), and inserted into the 1-d stellar models. We note that in these simulations, ...

Abstract Decaying grid turbulence is considered at low Reynolds number (Rλ ~ 50) for different initial conditions. Three different grid geometries are used. Heat is injected via a mandoline at a distance of 1.5 M from the grid. The amount of heating is such that temperature may be treated as a passive scalar. A small contraction (1.36:1) is added at a distance of 11M downstream of the grid. The...

It is often desirable to study turbulent flows at steady state even if the flow has no inherent source of turbulence kinetic energy. Doing so requires a forcing schema, and various methods applicable to laboratory experiments or numerical simulations have been studied extensively for turbulence that is isotropic and homogeneous in three dimensions. A review of existing schemata for simulations ...

1 Abstract In this paper we discuss the dynamical features of intermittent fluctuations in homogeneous shear flow turbulence. In this flow the energy cascade is strongly modified by the production of turbulent kinetic energy related to the presence of vortical structures induced by the shear. By using direct numerical simulations, we show that the refined Kolmogorov similarity is broken and a n...

The basic science of turbulence has been known for many years, yet the knowledge has hardly become a part of operational aviation turbulence forecasting. The history of turbulence forecasting, which has primarily concentrated at elevations above the boundary layer, has been an amalgamation of empirical rules of thumb and forecaster intuition, not of strong theory and conceptual models. Turbulen...

We present new observations from a microstructure-equipped ocean glider in the southeastern Beaufort Sea of the Canadian Arctic. The glider measured 345 quasi-vertical profiles of microstructure shear and finescale temperature and salinity. We use these measurements to calculate the rate of dissipation of turbulent kinetic energy and to assess the strength of turbulent mixing. The region is cha...