OIL DROPLET SIZE DISTRIBUTION AS A FUNCTION OF ENERGY DISSIPATION RATE IN AN EXPERIMENTAL WAVE TANK

2008 ◽  
Vol 2008 (1) ◽  
pp. 621-626 ◽  
Author(s):  
Zhengkai Li ◽  
Kenneth Lee ◽  
Thomas King ◽  
Michel C. Boufadel ◽  
Albert D. Venosa
Keyword(s):  
Energy Dissipation ◽  
Size Distribution ◽  
Dissipation Rate ◽  
Droplet Size Distribution ◽  
Breaking Waves ◽  
Energy Dissipation Rate ◽  
Wave Tank ◽  
Chemical Dispersant ◽  
Dispersed Oil ◽  
Dispersant Effectiveness

ABSTRACT The U.S. National Research Council (NRC) Committee on Understanding Oil Spill Dispersants: Efficacy and Effects (2005) identified two factors that require further investigation in chemical oil dispersant efficacy studies: 1) quantification of mixing energy at sea as energy dissipation rate and 2) dispersed particle size distribution. To fully evaluate the significance of these factors, a wave tank facility was designed and constructed to conduct controlled oil dispersion studies. A factorial experimental design was used to study the dispersant effectiveness as a function of energy dissipation rate for two oils and two dispersants under three different wave conditions, namely regular non-breaking waves, spilling breakers, and plunging breakers. The oils tested were weathered MESA and fresh ANS crude. The dispersants tested were Corexit 9500 and SPC 1000 plus water for no-dispersant control. The wave tank surface energy dissipatation rates of the three waves were determined to be 0.005, 0.1, and 1 m2/s3, respectively. The dispersed oil concentrations and droplet size distribution, measured by in-situ laser diffraction, were compared to quantify the chemical dispersant effectiveness as a function of energy dissipation rate. The results indicate that high energy dissipation rate of breaking waves enhanced chemical dispersant effectiveness by significantly increasing dispersed oil concentration and reducing droplet sizes in the water column (p <0.05). The presence of dispersants and breaking waves stimulated the oil dispersion kinetics. The findings of this research are expected to provide guidance to disperant application on oil spill responses.

DISPERSANT EFFECTIVENESS AS A FUNCTION OF ENERGY DISSIPATION RATE IN AN EXPERIMENTAL WAVE TANK

2008 ◽  
Vol 2008 (1) ◽  
pp. 777-783 ◽  
Author(s):  
A.D. Venosa ◽  
K. Lee ◽  
M. Boufadel ◽  
Z. Li ◽  
E. Wickley-Olsen ◽  
...  
Keyword(s):  
Particle Size ◽  
Energy Dissipation ◽  
Particle Size Distribution ◽  
Water Column ◽  
Size Distribution ◽  
Dissipation Rate ◽  
Breaking Waves ◽  
Energy Dissipation Rate ◽  
Wave Tank ◽  
Effective Dispersion

ABSTRACT In 2005, the National Research Council (NRC) published a comprehensive treatise on oil spill dispersants. Among other things, it concluded that research on dispersion effectiveness as a function of energy dissipation rate and particle size distribution was a high priority. Energy dissipation rate (turbulence and existence of breaking waves) is important to initiate and promote effective dispersion, and the particle size distribution of dispersed oil droplets affects dispersion and the ultimate fate of oil in the water column. In this paper, we discuss the use of a wave tank built on the premises of the Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada as part of collaborative research begun in 2003 by the U.S. Environmental Protection Agency (EPA) and Fisheries and Oceans Canada (DFO). This tank is able to produce breaking waves of various energy levels at precise locations in the tank. We studied the effects of 2 commercial dispersants (Corexit 9500 and SPC 1000) and a no dispersant control on two different crude oils (unweathered Alaska North Slope and weathered MESA Light) at 3 different energy dissipation rates (regular non-breaking waves, spilling breakers, and plunging breakers), amounting to 18 different treatments. We quantified the energy dissipation rates under those 3 wave conditions and measured oil dispersion in a factorial experiment involving 3 replicates of the 18 treatments over the course of the summer of 2006. Results clearly showed the importance of wave energy and the presence of a chemical dispersant on the ability to produce effective dispersion of oil into the water column. The presence of dispersants at increasing wave energies produced significantly better dispersion (p <0.05) than the no-dispersant controls. This study was conducted under batch conditions. Future work will be done under continuous flow conditions.

REGULAR AND BREAKING WAVES IN WAVE TANK FOR DISPERSION EFFECTIVENESS TESTING

2008 ◽  
Vol 2008 (1) ◽  
pp. 499-508 ◽  
Author(s):  
Erik Wickley-Olsen ◽  
Michel C. Boufadel ◽  
Tom King ◽  
Zhengkai Li ◽  
Ken Lee ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Water Column ◽  
Water Waves ◽  
Dissipation Rate ◽  
Breaking Waves ◽  
Energy Dissipation Rate ◽  
Regular Waves ◽  
Wave Tank ◽  
Plunging Breaker ◽  
Water Profile

ABSTRACT The wave tank (32 m long × 2.0 m high × 0.6 m wide) at the Bedford Institute of Oceanography in Nova Scotia was used to simulate the propagation and breaking of deep water waves using a flap-type wavemaker. The water profile and velocity were measured using a wave gauge and an Acoustic Doppler Velocimeter (ADV). The wave periods of interest ranged between 1.18 and 2.08 seconds. A technique for generating breaking waves at the same location in the tank was used to obtain a spilling and a plunging breaker. We evaluated the energy dissipation rate at various depths in the tank for regular and breaking waves. Plunging breaking waves had heights of 0.25m. For the breaking experiments, the energy dissipation rate decreased from around 1.0 10−2 watts/kg a few centimeters below the surface to less than 5.0 10−4 watt/kg 20 cm deep in the water column. The regular waves had, on the average, an energy dissipation rate of 5.0 10−6 watt/kg deep in the water column. This indicates that breaking plays an important role in the dispersion of oil at sea.

scholarly journals Estimating Energy Dissipation Rate from Breaking Waves Using Polarimetric SAR Images

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6540
Author(s):  
Rafael D. Viana ◽  
João A. Lorenzzetti ◽  
Jonas T. Carvalho ◽  
Ferdinando Nunziata
Keyword(s):  
Energy Dissipation ◽  
Total Energy ◽  
Dissipation Rate ◽  
Temporal Distribution ◽  
Wave Model ◽  
Breaking Waves ◽  
Fast Response ◽  
Energy Dissipation Rate ◽  
Sar Data ◽  
Total Energy Dissipation

The total energy dissipation rate on the ocean surface, ϵt (W m−2), provides a first-order estimation of the kinetic energy input rate at the ocean–atmosphere interface. Studies on the spatial and temporal distribution of the energy dissipation rate are important for the improvement of climate and wave models. Traditional oceanographic research normally uses remote measurements (airborne and platforms sensors) and in situ data acquisition to estimate ϵt; however, those methods cover small areas over time and are difficult to reproduce especially in the open oceans. Satellite remote sensing has proven the potential to estimate some parameters related to breaking waves on a synoptic scale, including the energy dissipation rate. In this paper, we use polarimetric Synthetic Aperture Radar (SAR) data to estimate ϵt under different wind and sea conditions. The used methodology consisted of decomposing the backscatter SAR return in terms of two contributions: a polarized contribution, associated with the fast response of the local wind (Bragg backscattering), and a non-polarized (NP) contribution, associated with wave breaking (Non-Bragg backscattering). Wind and wave parameters were estimated from the NP contribution and used to calculate ϵt from a parametric model dependent of these parameters. The results were analyzed using wave model outputs (WAVEWATCH III) and previous measurements documented in the literature. For the prevailing wind seas conditions, the ϵt estimated from pol-SAR data showed good agreement with dissipation associated with breaking waves when compared to numerical simulations. Under prevailing swell conditions, the total energy dissipation rate was higher than expected. The methodology adopted proved to be satisfactory to estimate the total energy dissipation rate for light to moderate wind conditions (winds below 10 m s−1), an environmental condition for which the current SAR polarimetric methods do not estimate ϵt properly.

scholarly journals Spectrally Resolved Energy Dissipation Rate and Momentum Flux of Breaking Waves

2008 ◽  
Vol 38 (6) ◽  
pp. 1296-1312 ◽  
Author(s):  
Johannes R. Gemmrich ◽  
Michael L. Banner ◽  
Chris Garrett
Keyword(s):  
Energy Dissipation ◽  
Wave Field ◽  
Wave Energy ◽  
Dissipation Rate ◽  
Momentum Flux ◽  
Phase Speed ◽  
Breaking Waves ◽  
Energy Dissipation Rate ◽  
Small Scale ◽  
Breaking Wave

Abstract Video observations of the ocean surface taken from aboard the Research Platform FLIP reveal the distribution of the along-crest length and propagation velocity of breaking wave crests that generate visible whitecaps. The key quantity assessed is Λ(c)dc, the average length of breaking crests per unit area propagating with speeds in the range (c, c + dc). Independent of the wave field development, Λ(c) is found to peak at intermediate wave scales and to drop off sharply at larger and smaller scales. In developing seas breakers occur at a wide range of scales corresponding to phase speeds from about 0.1 cp to cp, where cp is the phase speed of the waves at the spectral peak. However, in developed seas, breaking is hardly observed at scales corresponding to phase speeds greater than 0.5 cp. The phase speed of the most frequent breakers shifts from 0.4 cp to 0.2 cp as the wave field develops. The occurrence of breakers at a particular scale as well as the rate of surface turnover are well correlated with the wave saturation. The fourth and fifth moments of Λ(c) are used to estimate breaking-wave-supported momentum fluxes, energy dissipation rate, and the fraction of momentum flux supported by air-entraining breaking waves. No indication of a Kolmogorov-type wave energy cascade was found; that is, there is no evidence that the wave energy dissipation is dominated by small-scale waves. The proportionality factor b linking breaking crest distributions to the energy dissipation rate is found to be (7 ± 3) × 10−5, much smaller than previous estimates.

scholarly journals Effect of Turbulence on Collisional Growth of Cloud Droplets

2018 ◽  
Vol 75 (10) ◽  
pp. 3469-3487 ◽  
Author(s):  
Xiang-Yu Li ◽  
Axel Brandenburg ◽  
Gunilla Svensson ◽  
Nils E. L. Haugen ◽  
Bernhard Mehlig ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Size Distribution ◽  
Time Evolution ◽  
Dissipation Rate ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Collision Rate ◽  
Collision Model ◽  
Turbulent Energy Dissipation Rate ◽  
The Mean

We investigate the effect of turbulence on the collisional growth of micrometer-sized droplets through high-resolution numerical simulations with well-resolved Kolmogorov scales, assuming a collision and coalescence efficiency of unity. The droplet dynamics and collisions are approximated using a superparticle approach. In the absence of gravity, we show that the time evolution of the shape of the droplet-size distribution due to turbulence-induced collisions depends strongly on the turbulent energy-dissipation rate [Formula: see text], but only weakly on the Reynolds number. This can be explained through the [Formula: see text] dependence of the mean collision rate described by the Saffman–Turner collision model. Consistent with the Saffman–Turner collision model and its extensions, the collision rate increases as [Formula: see text] even when coalescence is invoked. The size distribution exhibits power-law behavior with a slope of −3.7 from a maximum at approximately 10 up to about 40 μm. When gravity is invoked, turbulence is found to dominate the time evolution of an initially monodisperse droplet distribution at early times. At later times, however, gravity takes over and dominates the collisional growth. We find that the formation of large droplets is very sensitive to the turbulent energy dissipation rate. This is because turbulence enhances the collisional growth between similar-sized droplets at the early stage of raindrop formation. The mean collision rate grows exponentially, which is consistent with the theoretical prediction of the continuous collisional growth even when turbulence-generated collisions are invoked. This consistency only reflects the mean effect of turbulence on collisional growth.

scholarly journals On the Relationship between the Energy Dissipation Rate of Surface-Breaking Waves and Oceanic Whitecap Coverage

2018 ◽  
Vol 48 (11) ◽  
pp. 2609-2626 ◽  
Author(s):  
Adrian H. Callaghan
Keyword(s):  
Energy Dissipation ◽  
Wind Speed ◽  
Penetration Depth ◽  
Dissipation Rate ◽  
Breaking Waves ◽  
Energy Dissipation Rate ◽  
Bubble Plume ◽  
Wind Speeds ◽  
Whitecap Coverage ◽  
Energy Balance Approach

AbstractWave breaking is the most important mechanism that leads to the dissipation of oceanic surface wave energy. A relationship between the energy dissipation rate associated with breaking wave whitecaps and the area of whitecap foam per unit area ocean surface is expected, but there is a lack of consensus on what form this relationship should take. Here, mathematical representations of whitecap coverage and growth-phase whitecap coverage are derived, and an energy-balance approach is used to formulate and in terms of . Both and are found to be linearly proportional to but also inversely proportional to the bubble plume penetration depth during active breaking. Since this depth can vary for breaking waves of different scales and slopes, there is likely no unique relationship between and either or as bubble plume penetration depth must also be specified. Whitecap observations from the North Atlantic are used to estimate bubble plume penetration depth as a function of wind speed and then used with measurements to compute . An estimate of the relative magnitude of to the rate of energy input from the wind to the waves is made. Above wind speeds of about 12 m s−1, is largely balanced by . At lower wind speeds the ratio quickly drops below unity with decreasing wind speed. It is proposed that sea-state-driven variability in both and bubble plume penetration depth are significant causes of variation in whitecap coverage datasets and parameterizations.

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