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.

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.

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.

Observations of the Particle Size Distribution and Concentration in a Coastal System using an In Situ Laser Analyzer

2002 ◽  
Vol 36 (1) ◽  
pp. 59-69 ◽  
Author(s):  
Teresa Serra ◽  
Xavier Casamitjana ◽  
Jordi Colomer ◽  
Timothy C. Granata
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Water Column ◽  
Size Distribution ◽  
Posidonia Oceanica ◽  
High Energy ◽  
Suspended Particles ◽  
Energy Conditions ◽  
Coastal System

An in situ laser particle size analyzer (LISST-100, Sequoia Scientific, Inc.) has been used to study the particle size distribution and concentration of biological and non biological particles in the water column of a Mediterranean coastal system. Two field campaigns have been carried out during low and high energy conditions of the flow, caused by the passage of a storm front. For the low energy period, the water column remained stratified, whereas for the high energetic period the water column was warmer and well mixed. The first study dealt with the distribution of particles near the bottom of the coastal area. Here, two regions were taken into account. The first region was a sea-grass meadow of Posidonia oceanica and the second region was a barren sand area. The second study dealt with the determination of the vertical distribution of suspended particles in the whole water column of the system. The results showed a decrease in the vertical concentration of suspended particles in the water column with the passage of the storm front, which was associated with advection of warm water mass rather than by vertical mixing. In contrast, vertical resuspension determined the fate of suspended particles at the bottom of the water column and an increase of their concentration was found.

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.

The Effect of Varying Salinity and Temperature on the Dynamics of Orimulsion in Water

2003 ◽  
Vol 2003 (1) ◽  
pp. 419-427
Author(s):  
Merv Fingas ◽  
Zhendi Wang ◽  
Mike Landriault ◽  
Jordan Noonan ◽  
Ron MacKay
Keyword(s):  
Time Series ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Water Column ◽  
Size Distribution ◽  
Brackish Water ◽  
Water Surface ◽  
Simple Equations

ABSTRACT Studies have shown that Orimulsion behaves somewhat predictably in saltwater (33 ppt NaCl) and freshwater, driven by buoyancy to rise in saltwater and sink in freshwater, but behaviour in brackish water (20 ppt NaCl) is difficult to predict. Temperature has also been indicated as having an influence on Orimulsion behaviour. The current study extended experimentation to lower temperatures and a large number of salinity values, ranging from fresh to saltwater. This study resulted in information on the behaviour of Orimulsion spills in salt, fresh, and brackish water with salinity values ranging from 0.1 to 33 °/oo at temperatures of 5 and 15 °C. Depletion rates and characteristics were determined by adding Orimulsion to a 300-L tank of water, taking a time series of samples, and determining the concentration of bitumen and the particle size distribution. Changes in bitumen concentration and particle size distribution as a function of time were also measured. Resurfaced bitumen was scraped from the top of the tank and weighed to determine the amount rising. Using these data, simple equations were developed to describe and predict the concentration of bitumen in the water column as a function of time. Similarly, nomograms showing the amount of oil on the bottom and on the water surface are presented.

scholarly journals The Influence of Whitecapping Waves on the Vertical Structure of Turbulence in a Shallow Estuarine Embayment

2008 ◽  
Vol 38 (7) ◽  
pp. 1563-1580 ◽  
Author(s):  
Nicole L. Jones ◽  
Stephen G. Monismith
Keyword(s):  
Energy Dissipation ◽  
Kinetic Energy ◽  
Water Column ◽  
Turbulent Kinetic Energy ◽  
San Francisco ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
Wall Layer ◽  
Breaking Wave ◽  
Bottom Boundary Layers

Abstract The vertical distribution of the turbulent kinetic energy dissipation rate was measured using an array of four acoustic Doppler velocimeters in the shallow embayment of Grizzly Bay, San Francisco Bay, California. Owing to the combination of wind and tide forcing in this shallow system, the surface and bottom boundary layers overlapped. Whitecapping waves were generated for a significant spectral peak steepness greater than 0.05 or above a wind speed of 3 m s−1. Under conditions of whitecapping waves, the turbulent kinetic energy dissipation rate in the upper portion of the water column was greatly enhanced, relative to the predictions of wind stress wall-layer theory. Instead, the dissipation followed a modified deep-water breaking-wave scaling. Near the bed (bottom 10% of the water column), the dissipation measurements were either equal to or less than that predicted by wall-layer theory. Stratification due to concentration gradients in suspended sediment was identified as the likely cause for these periods of production–dissipation imbalance close to the bed. During 50% of the well-mixed conditions experienced in the month-long experiment, whitecapping waves provided the dominant source of turbulent kinetic energy over 90% or more of the water column.

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