Impacts of wave-induced ocean surface turbulent kinetic energy flux on typhoon characteristics

Abstract. Coastal hydrodynamics can be greatly affected by the presence of submerged aquatic vegetation. The effect of vegetation has been incorporated into the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system. The vegetation implementation includes the plant-induced three-dimensional drag, in-canopy wave-induced streaming, and the production of turbulent kinetic energy by the presence of vegetation. In this study, we evaluate the sensitivity of the flow and wave dynamics to vegetation parameters using Sobol' indices and a least squares polynomial approach referred to as the Effective Quadratures method. This method reduces the number of simulations needed for evaluating Sobol' indices and provides a robust, practical, and efficient approach for the parameter sensitivity analysis. The evaluation of Sobol' indices shows that kinetic energy, turbulent kinetic energy, and water level changes are affected by plant stem density, height, and, to a lesser degree, diameter. Wave dissipation is mostly dependent on the variation in plant stem density. Performing sensitivity analyses for the vegetation module in COAWST provides guidance to optimize efforts and reduce exploration of parameter space for future observational and modeling work.

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Diurnal Dynamics of the Umov Kinetic Energy Density Vector in the Atmospheric Boundary Layer from Minisodar Measurements

Atmosphere ◽

10.3390/atmos12101347 ◽

2021 ◽

Vol 12 (10) ◽

pp. 1347

Author(s):

Alexander Potekaev ◽

Nikolay Krasnenko ◽

Liudmila Shamanaeva

Keyword(s):

Energy Density ◽

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Energy Flux ◽

Wind Effect ◽

Kinetic Energy Density ◽

Near Surface ◽

Density Vector ◽

The Mean ◽

Umov Vector

The diurnal hourly dynamics of the kinetic energy flux density vector, called the Umov vector, and the mean and turbulent components of the kinetic energy are estimated from minisodar measurements of wind vector components and their variances in the lower 200-meter layer of the atmosphere. During a 24-hour period of continuous minisodar observations, it was established that the mean kinetic energy density dominated in the surface atmospheric layer at altitudes below ~50 m. At altitudes from 50 to 100 m, the relative contributions of the mean and turbulent wind kinetic energy densities depended on the time of the day and the sounding altitude. At altitudes below 100 m, the contribution of the turbulent kinetic energy component is small, and the ratio of the turbulent to mean wind kinetic energy components was in the range 0.01–10. At altitudes above 100 m, the turbulent kinetic energy density sharply increased, and the ratio reached its maximum equal to 100–1000 at altitudes of 150–200 m. A particular importance of the direction and magnitude of the wind effect, that is, of the direction and magnitude of the Umov vector at different altitudes was established. The diurnal behavior of the Umov vector depended both on the time of the day and the sounding altitude. Three layers were clearly distinguished: a near-surface layer at altitudes of 5–15 m, an intermediate layer at altitudes from 15 m to 150 m, and the layer of enhanced turbulence above. The feasibility is illustrated of detecting times and altitudes of maximal and minimal wing kinetic energy flux densities, that is, time periods and altitude ranges most and least favorable for flights of unmanned aerial vehicles. The proposed novel method of determining the spatiotemporal dynamics of the Umov vector from minisodar measurements can also be used to estimate the effect of wind on high-rise buildings and the energy potential of wind turbines.

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A QUASI-3D TURBULENCE MODEL OF WAVE-INDUCED CURRENTS IN THE SURF ZONE USING ONE-EQUATION FOR TURBULENT KINETIC ENERGY

Advances in Fluid Modeling and Turbulence Measurements ◽

10.1142/9789812777591_0050 ◽

2002 ◽

Author(s):

MASAMITSU KUROIWA ◽

YUHEI MATSUBARA ◽

TAKUSHI INUKAI ◽

HIDEAKI NODA

Keyword(s):

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Turbulence Model ◽

Surf Zone ◽

Induced Currents ◽

Wave Induced

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Onset of stratification in a mixed layer subjected to a stabilizing buoyancy flux

Journal of Fluid Mechanics ◽

10.1017/s0022112095004332 ◽

1995 ◽

Vol 304 ◽

pp. 27-46 ◽

Cited By ~ 6

Author(s):

Y. Noh ◽

H. J. S. Fernando

Keyword(s):

Numerical Model ◽

Kinetic Energy ◽

Laboratory Experiment ◽

Water Column ◽

Turbulent Kinetic Energy ◽

Energy Flux ◽

Mixed Layer ◽

Mixed State ◽

Buoyancy Flux ◽

Tidal Front

The formation of a thermocline in a water column, in which shear-free turbulence is generated both at the surface and bottom, and a stabilizing buoyancy flux is imposed at the surface, is studied using a laboratory experiment and a numerical model with the aim of understanding the formation of a tidal front in coastal seas. The results show that the formation of a thermocline, which always occurs in the absence of bottom mixing, is inhibited and the water column maintains a vertically mixed state, when bottom mixing becomes sufficiently strong. It is found from both experimental and numerical results that the criterion for the formation of a thermocline is determined by the balance between the rate of work that is necessary to maintain a mixed state against the formation of stratification by the buoyancy flux and the turbulent kinetic energy flux from the bottom supplied to the depth of thermocline formation. The depth of the thermocline, when it is formed, is found to decrease with bottom mixing.

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Numerical Modelling of Wave Fields and Currents in Coastal Area

Water ◽

10.3390/w12061582 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1582

Author(s):

Francesco Gallerano

Keyword(s):

Kinetic Energy ◽

Numerical Simulations ◽

Turbulent Kinetic Energy ◽

Turbulence Model ◽

Wave Motion ◽

Three Dimensional ◽

Turbulence Models ◽

Wave Fields ◽

Induced Velocity ◽

Wave Induced

The design and management of coastal engineering, like harbors and coastal defense structures, requires the simulation of hydrodynamic phenomena. This special issue collects five original papers that address state of the art numerical simulations of wave fields and wave-induced velocity fields in coastal areas. The first paper proposes a turbulence model for wave breaking simulation, which is expressed in terms of turbulent kinetic energy and dissipation rate of turbulent kinetic energy (k − ε); the proposed turbulence model is a modification of the standard k − ε turbulence models. The second paper investigates modalities by which wind interacts with wave motion, modifying the wave propagation dynamic. The third paper proposes a study on waves overtopping over coastal barriers. The fourth paper details the numerical simulation of a tsunami wave that propagates over an artificial reservoir, caused by a landslide that creates a solid mass to detach from the slopes and to slide into the reservoir. The fifth paper examines an application case concerning Cetraro harbor (Italy), which is carried out using three-dimensional numerical simulations of wave motion.

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Sensitivity Analysis of a Coupled Hydrodynamic-Vegetation Model Using the Effectively Subsampled Quadratures Method

10.5194/gmd-2017-107 ◽

2017 ◽

Author(s):

Tarandeep S. Kalra ◽

Alfredo Aretxabaleta ◽

Pranay Seshadri ◽

Neil K. Ganju ◽

Alexis Beudin

Keyword(s):

Sensitivity Analysis ◽

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Aquatic Vegetation ◽

Plant Density ◽

Three Dimensional ◽

Sensitivity Analyses ◽

Sobol Indices ◽

Wave Dynamics ◽

Wave Induced

Abstract. Coastal hydrodynamics can be greatly affected by the presence of submerged aquatic vegetation. The effect of vegetation has been incorporated into the Coupled-Ocean-Atmosphere-Wave-Sediment Transport (COAWST) Modeling System. The vegetation implementation includes the plant-induced three-dimensional drag, in-canopy wave-induced streaming, and the production of turbulent kinetic energy by the presence of vegetation. In this study, we evaluate the sensitivity of the flow and wave dynamics to vegetation parameters using Sobol' indices and a least squares polynomial approach referred to as Effective Quadratures method. This method reduces the number of simulations needed for evaluating Sobol' indices and provides a robust, practical, and efficient approach for the parameter sensitivity analysis. The evaluation of Sobol' indices shows that kinetic energy, turbulent kinetic energy, and water level changes are affected by plant density, height, and to a certain degree, diameter. Wave dissipation is mostly dependent on the variation in plant density. Performing sensitivity analyses for the vegetation module in COAWST provides guidance for future observational and modeling work to optimize efforts and reduce exploration of parameter space.

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Near-surface turbulence and buoyancy induced by heavy rainfall

Journal of Fluid Mechanics ◽

10.1017/jfm.2017.602 ◽

2017 ◽

Vol 830 ◽

pp. 602-630 ◽

Cited By ~ 6

Author(s):

E. L. Harrison ◽

F. Veron

Keyword(s):

Energy Dissipation ◽

Kinetic Energy ◽

Turbulent Kinetic Energy ◽

Energy Flux ◽

Terminal Velocity ◽

Near Surface ◽

Wave Channel ◽

Surface Turbulence ◽

Rain Drop ◽

The Impact

We present results from experiments designed to measure near-surface turbulence generated by rainfall. Laboratory experiments were performed using artificial rain falling at near-terminal velocity in a wind–wave channel filled with synthetic seawater. In this first series of experiments, no wind was generated and the receiving seawater was initially at rest. Rainfall rates from 40 to $190~\text{mm}~\text{h}^{-1}$ were investigated. Subsurface turbulent velocities of the order of $O(10^{-2})~\text{m}~\text{s}^{-1}$ are generated near the interface below the depth of the cavities generated by the rain drop impacts. The turbulence appears independent of rainfall rates. At depth larger than the size of the cavities, the turbulent velocity fluctuations decay as $z^{-3/2}$. Turbulent length scales also appear to scale with the size of the impact cavities. In these seawater experiments, a freshwater lens is established at the water surface due to the rain. At the highest rain rate studied, the resulting buoyancy flux appears to lead to a shallower subsurface mixed layer and a slight decrease of the turbulent kinetic energy dissipation. Finally, direct measurements and inertial estimates of the turbulent kinetic energy dissipation show that approximately 0.1–0.3 % of the kinetic energy flux from the rain is dissipated in the form of turbulence. This is consistent with existing freshwater measurements and suggests that high levels of dissipation occur at depths and scales smaller than those resolved here and/or that other phenomena dissipate a considerable amount of the total kinetic energy flux provided by rainfall.

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