Turbulent kinetic energy balance in the atmospheric surface layer over a tropical region

ABSTRACT. The various tenns of the turbulent kinetic energy budget in the surface layer over Jodhpur, India have been worked out and compared with established similarity relations. The turbulent production and dissipation tend to balance under moderately unstable conditions for most of the runs considered for investigation.

Turbulent Kinetic Energy and Budget of Heterogeneous Open Channel with Gravel and Vegetated Beds

Turbulent kinetic energy (TKE) and budget are indispensable hydraulic parameters to determine turbulent scales and processes resulting from various and different natural hydraulic features in open channels. This paper focuses on experimental investigation of turbulent kinetic energy and budget in a heterogeneous open channel flow with gravel and vegetated beds. Results indicate the turbulent kinetic energy (TKE) value over gravel region of the heterogeneous bed remains approximately constant with flow depth. The highest turbulent kinetic energy was calculated for flexible vegetation arrangement compared to the rigid vegetation. The estimation of the turbulent kinetic energy budget shows the higher values of turbulence production recorded over the flexible vegetated bed, consequently, the dissipation rate exhibits faster decay of turbulence kinetic energy over the vegetated bed in comparison to the gravel bed.

Large Eddy Simulation Coupling Model For Small-scale Air-sea Interaction

<p>Atmosphere and ocean are two important factors that affect the earth's climate system, and their interaction is an important topic in the study. In view of the lack of turbulence scale analysis in the traditional large-scale air-sea coupling model, this paper uses the Parallelized Large-Eddy Simulation Model (PALM) to explore the effect of Langmuir circulation on air-sea flux and turbulent kinetic energy budget at a small scale, and conducts air-sea coupled simulation for atmospheric boundary layer (ABL) and ocean mixed layer (OML). The results show that the distribution of air-sea flux near the surface is greatly influenced by the Langmuir circulation, thus strengthening the ocean mixing. The pressure term in the turbulent kinetic energy budget of the ocean is greatly affected by the Langmuir circulation near the sea surface and weakens rapidly as the depth deepens. This study shows the application of the small-scale air-sea coupling model in the study of air-sea flux, which has certain significance for the study of small-scale air-sea interaction.</p>

Impact of frontal round jet on vortex synchronization control around a cylinder: a turbulence perspective

The present study demonstrates that a round turbulent jet issued from a cylinder surface towards the upstream against the current can be a controlling parameter for vortex synchronization (VSC) in the wake region (WR) of the vertical cylinder. The results depict that the VSC state can be reached when the jet excitation frequency and the natural shedding frequency (NSF) are almost equal, or the jet excitation frequency is double that of the NSF. Precisely for VSC case, the turbulent production and dissipation terms of the turbulent kinetic energy budget equation contribute majorly to the total energy at the reattachment region with shifting of energy from the pressure and the turbulent diffusion terms. The enhancement of intermittency in turbulence for the VSC cases is also pertinent.

Ablation of sloping ice faces into polar seawater

The effects of the slope of an ice–seawater interface on the mechanisms and rate of ablation of the ice by natural convection are examined using turbulence-resolving simulations. Solutions are obtained for ice slopes $\unicode[STIX]{x1D703}=2^{\circ }{-}90^{\circ }$, at a fixed ambient salinity and temperature, chosen to represent common Antarctic ocean conditions. For laminar boundary layers the ablation rate decreases with height, whereas in the turbulent regime the ablation rate is found to be height independent. The simulated laminar ablation rates scale with $(\sin \unicode[STIX]{x1D703})^{1/4}$, whereas in the turbulent regime it follows a $(\sin \unicode[STIX]{x1D703})^{2/3}$ scaling, both consistent with the theoretical predictions developed here. The reduction in the ablation rate with shallower slopes arises as a result of the development of stable density stratification beneath the ice face, which reduces turbulent buoyancy fluxes to the ice. The turbulent kinetic energy budget of the flow shows that, for very steep slopes, both buoyancy and shear production are drivers of turbulence, whereas for shallower slopes shear production becomes the dominant mechanism for sustaining turbulence in the convective boundary layer.