scholarly journals Effects of wind on the dynamics of the central jet during drop impact onto a deep-water surface

2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Xinan Liu ◽  
An Wang ◽  
Shuang Wang ◽  
Dejun Dai
Keyword(s):  
Deep Water ◽  
Water Surface ◽  
Drop Impact

scholarly journals Experimental Study of Drop Impact on Deep-Water Surface in the Presence of Wind

2018 ◽  
Vol 48 (2) ◽  
pp. 329-341 ◽  
Author(s):  
Xinan Liu
Keyword(s):  
Deep Water ◽  
Water Surface ◽  
Water Drop ◽  
Threshold Value ◽  
Impact Angle ◽  
Drop Impact ◽  
Wind Speeds ◽  
Secondary Droplets ◽  
Low Wind Speeds ◽  
The Impact

AbstractThe effects of wind on the impact of a single water drop on a deep-water surface are studied experimentally in a wind tunnel. Experiments are performed by varying impacting drop diameters, ranging from 2.5 to 4.1 mm and wind speeds up to 6.7 m s−1. The sequence of splashing events that occurred during drop impacts is recorded with a backlit, cinematic shadowgraph technique. The experimental results show that for low wind speeds, an asymmetrical crown forms on the leeward of the periphery of the colliding region after the drop hits the water surface, while a wave swell forms on the windward. Secondary droplets are generated from the crown rim. For high wind speeds with large drop diameters, ligaments are generated from the crown rim on the leeward of the drop impact site. The ligaments grow, coalesce, and fragment into secondary droplets. It is found that both the drag force and surface tension play important roles in the evolution process of the ligaments. The nondimensional K number (K = WeOh−0.4, where We is the Webber number and Oh is the Ohnesorge number) is used to describe the splashing-deposition limit of drop impact. The threshold value of this K number changes with the wind velocity and/or drop impact angle.

Action of an adverse current on the shape of deep water surface waves

1995 ◽  
Vol 18 (6) ◽  
pp. 438-444 ◽  
Author(s):  
P. Bonmarin ◽  
F. Bartholin ◽  
A. Ramamonjiarisoa
Keyword(s):  
Surface Waves ◽  
Deep Water ◽  
Water Surface

Refraction of gravity waves by weak current gradients

2001 ◽  
Vol 442 ◽  
pp. 157-159 ◽  
Author(s):  
KRISTIAN B. DYSTHE
Keyword(s):  
Surface Waves ◽  
Group Velocity ◽  
Gravity Waves ◽  
Deep Water ◽  
Current Velocity ◽  
Water Surface ◽  
Simple Formula ◽  
Vertical Component ◽  
Weak Current ◽  
The Waves

When deep water surface waves cross an area with variable current, refraction takes place. If the group velocity of the waves is much larger than the current velocity we show that the curvature of a ray, χ, is given by the simple formula χ = ζ/vg. Here ζ is the vertical component of the current vorticity and vg is the group velocity.

scholarly journals Vortex generation by deep-water breaking waves

2013 ◽  
Vol 734 ◽  
pp. 198-218 ◽  
Author(s):  
N. E. Pizzo ◽  
W. Kendall Melville
Keyword(s):  
Deep Water ◽  
Water Surface ◽  
Body Force ◽  
Scale Effects ◽  
Breaking Waves ◽  
The Body ◽  
Surface Gravity ◽  
Breaking Wave ◽  
Shear Stresses ◽  
Mean Flow

AbstractThe connection between wave dissipation by breaking deep-water surface gravity waves and the resulting turbulence and mixing is crucial for an improved understanding of air–sea interaction processes. Starting with the ensemble-averaged Euler equations, governing the evolution of the mean flow, we model the forcing, associated with the breaking-induced Reynolds shear stresses, as a body force describing the bulk scale effects of a breaking deep-water surface gravity wave on the water column. From this, we derive an equation describing the generation of circulation, $\Gamma $, of the ensemble-average velocity field, due to the body force. By examining the relationship between a breaking wave and an impulsively forced fluid, we propose a functional form for the body force, allowing us to build upon the classical work on vortex ring phenomena to both quantify the circulation generated by a breaking wave and describe the vortex structure of the induced motion. Using scaling arguments, we show that $\Gamma = \alpha {(hk)}^{3/ 2} {c}^{3} / g$, where ($c, h, k$) represent a characteristic speed, height and wavenumber of the breaking wave, respectively, $g$ is the acceleration due to gravity and $\alpha $ is a constant. This then allows us to find a direct relationship between the circulation and the wave energy dissipation rate per unit crest length due to breaking, ${\epsilon }_{l} $. Finally, we compare our model and the available experimental data.

scholarly journals The effect of randomness on the stability of deep water surface gravity waves in the presence of a thin thermocline

1998 ◽  
Vol 40 (2) ◽  
pp. 190-206
Author(s):  
Sudebi Bhattacharyya ◽  
K. P. Das
Keyword(s):  
Growth Rate ◽  
Evolution Equation ◽  
Gravity Waves ◽  
Fourth Order ◽  
Deep Water ◽  
Water Surface ◽  
Spectral Width ◽  
Surface Gravity ◽  
Surface Gravity Waves ◽  
The Stability

AbstractThe effect of randomness on the stability of deep water surface gravity waves in the presence of a thin thermocline is studied. A previously derived fourth order nonlinear evolution equation is used to find a spectral transport equation for a narrow band of surface gravity wave trains. This equation is used to study the stability of an initially homogeneous Lorentz shape of spectrum to small long wave-length perturbations for a range of spectral widths. The growth rate of the instability is found to decrease with the increase of spectral widths. It is found that the fourth order term in the evolution equation produces a decrease in the growth rate of the instability. There is stability if the spectral width exceeds a certain critical value. For a vanishing bandwidth the deterministic growth rate of the instability is recovered. Graphs have been plotted showing the variations of the growth rate of the instability against the wavenumber of the perturbation for some different values of spectral width, thermocline depth, angle of perturbation and wave steepness.

Evaluation of Oil Fate and Exposure from a Deep Water Blowout With and Without Subsea Dispersant Injection Treatment as Well as Traditional Response Activities

2017 ◽  
Vol 2017 (1) ◽  
pp. 362-382 ◽  
Author(s):  
Deborah French-McCay ◽  
Deborah Crowley ◽  
Jill Rowe
Keyword(s):  
Surface Water ◽  
Deep Water ◽  
Water Surface ◽  
Oil And Gas ◽  
Early Life History ◽  
Water Volume ◽  
Response Options ◽  
Degradation Rates ◽  
Order Of Magnitude ◽  
Wind Currents

ABSTRACT The goals of subsea dispersant injection (SSDI) into a deep water oil and gas blowout are to increase effectiveness of dispersant treatment over that achievable at the water surface; decrease the volume of oil that surfaces; reduce human and wildlife exposure to volatile organic compounds (VOCs); disperse the oil over a large water volume at depth; enhance biodegradation; and reduce surface, nearshore and shoreline exposure to floating and surface-water entrained/dissolved oil. Potential tradeoffs include increased water column and benthic resource exposures to oil at depth. In order to better understand the implications of SSDI use, we modeled a hypothetical blowout in the northern Gulf of Mexico to predict oil fate and compare the environmental exposure for no intervention to various response options (i.e., mechanical recovery, in-situ burning (ISB), surface dispersant application, and SSDI). Probabilistic modeling was used to evaluate the influence of variable metocean conditions (i.e., wind, currents, temperature). The results showed that even with a substantial capacity of equipment applied, mechanical and ISB removed only a small fraction of the oil that would otherwise be floating or evaporate. Compared to cases without use of SSDI, SSDI reduced the size of oil droplets by an order of magnitude, substantially decreased the amount of oil on the water surface and on the shoreline, increased dissolution and degradation rates of hydrocarbons at depth, increased weathering rate of rising oil such that floating oil contained much lower content of soluble and semi-soluble hydrocarbons, decreased surface water concentrations of dissolved hydrocarbons, and decreased VOC emissions to the atmosphere and, therefore, reduced human and wildlife exposures to VOCs. The tradeoff was that with SSDI there was greater exposure to hydrocarbons in deep water. However, densities of biota are much lower in deep water than near the water surface, where sensitive early life history stages of fish and invertebrates are most abundant. This approach provides decision makers with quantitative environmental exposures with which they may evaluate risk tradeoffs regarding appropriate response strategies for mitigating impacts from oil and gas released during a deep water blowout.

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