This page has only limited features, please log in for full access.
The fate and transport of sediment plumes in the ocean, such as those resulting from the disposal of deep-sea mining residuals, are affected by ambient crossflow. We present laboratory measurements of the depth at which a particle plume is trapped by ambient stratification for various crossflow and particle settling velocities. Results suggest that the trap depth declines exponentially with crossflow velocity but is relatively insensitive to settling velocity in the range studied. An empirical correlation based on the laboratory data is validated by a larger scale field experiment involving simulated disposal of deep-sea mining wastes.
Dayang Wang; E. Eric Adams; Carlos Munoz-Royo; Thomas Peacock; Matthew H. Alford. Effect of crossflow on trapping depths of particle plumes: laboratory experiments and application to the PLUMEX field experiment. Environmental Fluid Mechanics 2021, 21, 741 -757.
AMA StyleDayang Wang, E. Eric Adams, Carlos Munoz-Royo, Thomas Peacock, Matthew H. Alford. Effect of crossflow on trapping depths of particle plumes: laboratory experiments and application to the PLUMEX field experiment. Environmental Fluid Mechanics. 2021; 21 (4):741-757.
Chicago/Turabian StyleDayang Wang; E. Eric Adams; Carlos Munoz-Royo; Thomas Peacock; Matthew H. Alford. 2021. "Effect of crossflow on trapping depths of particle plumes: laboratory experiments and application to the PLUMEX field experiment." Environmental Fluid Mechanics 21, no. 4: 741-757.
Confined plunging jets are investigated as potential outfalls for the discharge of desalination brine. Compared to offshore submerged outfalls that rely on momentum to induce mixing, plunging jets released above the water surface utilize both momentum and negative buoyancy. Plunging jets also introduce air into the water column, which can reduce the possibility of hypoxic zones. In contrast to unconfined plunging jets, confined plunging jets include a confining tube, or downcomer, around the jet, which increases the penetration depth of the bubbles and can provide better aeration. However, the presence of this downcomer can hinder mixing with surrounding water. Therefore, laboratory measurements of dilution are reported here and compared to the dilution of unconfined plunging jets. In addition, qualitative observations of bubble penetration depth are also used to discuss aeration potential. For designs that increase the bubble penetration depth as compared to unconfined plunging jets, results show that dilution decreases as the depth of the downcomer is increased. However, it is shown that confined plunging jets can be designed with a short downcomer to provide higher dilution than unconfined jets. The effect of the diameter of downcomer on dilution is also investigated and a non-monotonic effect is observed.
Ishita Shrivastava; Edward Adams; Bader Al-Anzi; Aaron Chow; Jongyoon Han. Confined Plunging Liquid Jets for Dilution of Brine from Desalination Plants. Processes 2021, 9, 856 .
AMA StyleIshita Shrivastava, Edward Adams, Bader Al-Anzi, Aaron Chow, Jongyoon Han. Confined Plunging Liquid Jets for Dilution of Brine from Desalination Plants. Processes. 2021; 9 (5):856.
Chicago/Turabian StyleIshita Shrivastava; Edward Adams; Bader Al-Anzi; Aaron Chow; Jongyoon Han. 2021. "Confined Plunging Liquid Jets for Dilution of Brine from Desalination Plants." Processes 9, no. 5: 856.
Laboratory experiments were conducted to measure entrained air bubble penetration depth and dilution of a dense vertical unconfined plunging jet to evaluate its performance as an outfall to dilute brine from desalination plants as well as a means to aerate water column. Experiments involved neutrally buoyant or dense plunging jets discharging in quiescent receiving water. The density difference between effluent and receiving water, the plunging jet length (height above water surface), and the receiving water salinity were varied in the experiments. Observed penetration depth for neutrally buoyant jets was somewhat greater than previously reported, and increased modestly with jet density. Increasing density also resulted in an increasing number of fine bubbles descending together with the dense plume. These observations can help guide the design of plunging jets to mitigate anoxic conditions in the water column when brine is introduced to a receiving water body, as with seawater desalination.
Aaron C. Chow; Ishita Shrivastava; E. Eric Adams; Fahed Al-Rabaie; Bader Al-Anzi. Unconfined Dense Plunging Jets Used for Brine Disposal from Desalination Plants. Processes 2020, 8, 1 .
AMA StyleAaron C. Chow, Ishita Shrivastava, E. Eric Adams, Fahed Al-Rabaie, Bader Al-Anzi. Unconfined Dense Plunging Jets Used for Brine Disposal from Desalination Plants. Processes. 2020; 8 (6):1.
Chicago/Turabian StyleAaron C. Chow; Ishita Shrivastava; E. Eric Adams; Fahed Al-Rabaie; Bader Al-Anzi. 2020. "Unconfined Dense Plunging Jets Used for Brine Disposal from Desalination Plants." Processes 8, no. 6: 1.
Brine discharges from desalination plants into low-flushing water bodies are challenging from the point of view of dilution, because of the possibility of background buildup effects that decrease the overall achievable dilution. To illustrate the background buildup effect, this paper uses the Arabian (Persian) Gulf, a shallow, reverse tidal estuary with only one outlet available for exchange flow. While desalination does not significantly affect the long-term average Gulf-wide salinity, due to the mitigating effect of the Indian Ocean Surface Water inflow, its resulting elevated salinities, as well as elevated concentrations of possible contaminants (such as heavy metals and organophosphates), can affect marine environments on a local and regional scale. To analyze the potential effect of background salinity buildup on dilutions achievable from discharge locations in the northern Gulf, a 3-dimensional hydrodynamic model (Delft3D) was used to simulate brine discharges from a single hypothetical source location along the Kuwaiti shoreline, about 900 km from the Strait of Hormuz. Using nested grids with a horizontal resolution, comparable to a local tidal excursion (250 m), far field dilutions of about 28 were computed for this discharge location. With this far field dilution, to achieve a total dilution of 20, the near field dilution (achievable using a submerged diffuser) would need to be increased to approximately 70. Conversely, the background build-up means that a near field dilution of 20 yields a total dilution of only about 12.
Aaron C. Chow; Wilbert Verbruggen; Robin Morelissen; Yousef Al-Osairi; Poornima Ponnumani; Haitham M. S. Lababidi; Bader Al-Anzi; E. Eric Adams. Numerical Prediction of Background Buildup of Salinity Due to Desalination Brine Discharges into the Northern Arabian Gulf. Water 2019, 11, 2284 .
AMA StyleAaron C. Chow, Wilbert Verbruggen, Robin Morelissen, Yousef Al-Osairi, Poornima Ponnumani, Haitham M. S. Lababidi, Bader Al-Anzi, E. Eric Adams. Numerical Prediction of Background Buildup of Salinity Due to Desalination Brine Discharges into the Northern Arabian Gulf. Water. 2019; 11 (11):2284.
Chicago/Turabian StyleAaron C. Chow; Wilbert Verbruggen; Robin Morelissen; Yousef Al-Osairi; Poornima Ponnumani; Haitham M. S. Lababidi; Bader Al-Anzi; E. Eric Adams. 2019. "Numerical Prediction of Background Buildup of Salinity Due to Desalination Brine Discharges into the Northern Arabian Gulf." Water 11, no. 11: 2284.
Biodegradation is important for the fate of oil spilled in marine environments, yet parameterization of biodegradation varies across oil spill models, which usually apply constant first-order decay rates to multiple pseudo-components describing an oil. To understand the influence of model parameterization on the fate of subsurface oil droplets, we reviewed existing algorithms and rates and conducted a model sensitivity study. Droplets were simulated from a blowout at 2000 m depth and were either treated with sub-surface dispersant injection (2% dispersant to oil ratio) or untreated. The most important factor affecting oil fate was the size of the droplets, with biodegradation contributing substantially to the fate of droplets ≤0.5 mm. Oil types, which were similar, had limited influence on simulated oil fate. Model results suggest that knowledge of droplet sizes and improved estimation of pseudo-component biodegradation rates and lag times would enhance prediction of the fate and transport of subsurface oil.
Scott A. Socolofsky; Jonas Gros; Elizabeth North; Michel C. Boufadel; Thomas F. Parkerton; E. Eric Adams. The treatment of biodegradation in models of sub-surface oil spills: A review and sensitivity study. Marine Pollution Bulletin 2019, 143, 204 -219.
AMA StyleScott A. Socolofsky, Jonas Gros, Elizabeth North, Michel C. Boufadel, Thomas F. Parkerton, E. Eric Adams. The treatment of biodegradation in models of sub-surface oil spills: A review and sensitivity study. Marine Pollution Bulletin. 2019; 143 ():204-219.
Chicago/Turabian StyleScott A. Socolofsky; Jonas Gros; Elizabeth North; Michel C. Boufadel; Thomas F. Parkerton; E. Eric Adams. 2019. "The treatment of biodegradation in models of sub-surface oil spills: A review and sensitivity study." Marine Pollution Bulletin 143, no. : 204-219.
Buoyant jets or forced plumes are discharged into a turbulent ambient in many natural and engineering applications. The background turbulence generally affects the mixing characteristics of the buoyant jet, and the extent of the influence depends on the characteristics of both the jet discharge and ambient. Previous studies focused on the experimental investigation of the problem (for pure jets or plumes), but the findings were difficult to generalize because suitable scales for normalization of results were not known. A model to predict the buoyant jet mixing in the presence of background turbulence, which is essential in many applications, is also hitherto not available even for a background of homogeneous and isotropic turbulence (HIT). We carried out experimental and theoretical investigations of a buoyant jet discharging into background HIT. Buoyant jets were designed to be in the range of $1, where $l_{M}=M_{o}^{3/4}/F_{o}^{1/2}$ is the momentum length scale, with $z/l_{M}<\sim 1$ and $z/l_{M}>\sim 6$ representing the asymptotic cases of pure jets and plumes, respectively. The background turbulence was generated using a random synthetic jet array, which produced a region of approximately isotropic and homogeneous field of turbulence to be used in the experiments. The velocity scale of the jet was initially much higher, and the length scale smaller, than that of the background turbulence, which is typical in most applications. Comprehensive measurements of the buoyant jet mixing characteristics were performed up to the distance where jet breakup occurred. Based on the experimental findings, a critical length scale $l_{c}$ was identified to be an appropriate normalizing scale. The momentum flux of the buoyant jet in background HIT was found to be conserved only if the second-order turbulence statistics of the jet were accounted for. A general integral jet model including the background HIT was then proposed based on the conservation of mass (using the entrainment assumption), total momentum and buoyancy fluxes, and the decay function of the jet mean momentum downstream. Predictions of jet mixing characteristics from the new model were compared with experimental observation, and found to be generally in agreement with each other.
Adrian C. H. Lai; Adrian Wing-Keung Law; E. Eric Adams. A second-order integral model for buoyant jets with background homogeneous and isotropic turbulence. Journal of Fluid Mechanics 2019, 871, 271 -304.
AMA StyleAdrian C. H. Lai, Adrian Wing-Keung Law, E. Eric Adams. A second-order integral model for buoyant jets with background homogeneous and isotropic turbulence. Journal of Fluid Mechanics. 2019; 871 ():271-304.
Chicago/Turabian StyleAdrian C. H. Lai; Adrian Wing-Keung Law; E. Eric Adams. 2019. "A second-order integral model for buoyant jets with background homogeneous and isotropic turbulence." Journal of Fluid Mechanics 871, no. : 271-304.
High discharge salinity of reject brine from desalination plants necessitates the use of submerged jets which induce mixing with ambient water and lead to reduction in concentrations of salt and other contaminants. Pre-dilution, in which brine is blended with a lighter effluent prior to discharge, can also cause reduction in contaminant concentrations. Condenser cooling water from a co-located power plant, treated wastewater effluent from a treatment plant and seawater can be used for pre-dilution. The effect of pre-dilution on shallowness and contaminant concentrations in the diluted effluent is examined for discharge using single port and multiport outfalls. The density difference between the effluent and ambient seawater is lower for the discharge of pre-diluted brine, which leads to shallow conditions. Pre-dilution also results in lower concentrations of contaminants in the diluted effluent by reducing the discharge concentrations as well as increasing outfall dilution in deep water by increasing the densimetric Froude number. This helps in satisfying regulatory requirements on contaminant concentrations with small discharge velocity or using outfalls with small number of ports. While discharge of pre-diluted brine using an existing outfall helps save on the capital cost, it can cause a significant increase in pumping cost. For a new outfall, design parameters can be adjusted such that pumping cost stays constant.
Ishita Shrivastava; E. Eric Adams. Pre-dilution of desalination reject brine: Impact on outfall dilution in different water depths. Journal of Hydro-environment Research 2018, 24, 28 -35.
AMA StyleIshita Shrivastava, E. Eric Adams. Pre-dilution of desalination reject brine: Impact on outfall dilution in different water depths. Journal of Hydro-environment Research. 2018; 24 ():28-35.
Chicago/Turabian StyleIshita Shrivastava; E. Eric Adams. 2018. "Pre-dilution of desalination reject brine: Impact on outfall dilution in different water depths." Journal of Hydro-environment Research 24, no. : 28-35.
An improved light attenuation method [light attenuation method for two-dimensional data acquisition (LAM2D)] to quantify two-dimensional (2D) sediment depths with higher accuracy is developed in the present study. The working principle is to relate attenuated light intensities with depths of the sediment layer. Traditionally, calibration has been performed with the scraper method with either multiple constant sediment depth profiles or a slope with incremental depth profile. This method works well for coarse sediment but is shown to be inaccurate for fine sediment with shallow sediment depth in the near-zero limit regime. In the present study, a new method is established for the calibration of shallow sediment depth by using the correlation of particle plume deposition profiles. The practical application of LAM2D to determine sediment deposition profiles from a laboratory simulation of barged sediment disposal was demonstrated with both approaches. The errors in the overall determination of sediment mass were found to be significantly reduced with the current approach.
Jenn Wei Er; Wing Keung Adrian Law; E. Eric Adams; Yang Yang. Improved Light Attenuation Method for 2D Data Acquisition of Sediment Depths. Journal of Hydraulic Engineering 2018, 144, 04018028 .
AMA StyleJenn Wei Er, Wing Keung Adrian Law, E. Eric Adams, Yang Yang. Improved Light Attenuation Method for 2D Data Acquisition of Sediment Depths. Journal of Hydraulic Engineering. 2018; 144 (6):04018028.
Chicago/Turabian StyleJenn Wei Er; Wing Keung Adrian Law; E. Eric Adams; Yang Yang. 2018. "Improved Light Attenuation Method for 2D Data Acquisition of Sediment Depths." Journal of Hydraulic Engineering 144, no. 6: 04018028.
Engineering activities, such as disposal of dredged materials or land reclamation, produce sediment clouds that can be characterized by a descending thermal and a trailing stem resulting from an instantaneous release. The mass loss from the trailing stem during the descent induces turbidity in the water column and this is investigated in this study. The experimental data of trailing stems from previous studies were reanalyzed to derive a relationship between the mass loss to the trailing stem and the sediment release conditions. The normalized trailing stem length and the cumulative mass distribution within the stem were then obtained. Finally, an application of the model to estimate the sediment loss to the ambient during sediment disposal is given.
Adrian C. H. Lai; E. Eric Adams; Wing Keung Adrian Law. Mass Loss to the Trailing Stem of a Sediment Cloud. Journal of Hydraulic Engineering 2018, 144, 06018003 .
AMA StyleAdrian C. H. Lai, E. Eric Adams, Wing Keung Adrian Law. Mass Loss to the Trailing Stem of a Sediment Cloud. Journal of Hydraulic Engineering. 2018; 144 (4):06018003.
Chicago/Turabian StyleAdrian C. H. Lai; E. Eric Adams; Wing Keung Adrian Law. 2018. "Mass Loss to the Trailing Stem of a Sediment Cloud." Journal of Hydraulic Engineering 144, no. 4: 06018003.
Integral models of single-phase plumes are often closed using the entrainment hypothesis, which assumes the entrainment velocity is proportional to a characteristic plume velocity, but the corresponding theoretical development for modeling particle plumes has received less attention. In this paper an integral model is developed by proposing a new spreading hypothesis for particle plumes, in which the fluid phase spreading rate is taken as that of a single-phase plume, whereas the particle phase spreading rate is a function of the particle phase and fluid phase average vertical velocity. The change in momentum flux of the particle and fluid phases are calculated by considering the cross-sectional integrated buoyant and drag forces acting on the particles, and their reaction force acting on the fluid. Mixing characteristics of the particle plume can then be determined. The model was validated by laboratory particle plume experiments conducted for various particle sizes and initial plume-to-particle-settling velocity ratios, as well as experiments in the literature. Centerline particle and fluid velocities, as well as particle concentrations were generally well predicted. The inferred entrainment coefficient for a particle plume and the importance of lift force are also discussed.
Adrian C. H. Lai; S. N. Chan; Wing Keung Adrian Law; E. Eric Adams. Spreading Hypothesis of a Particle Plume. Journal of Hydraulic Engineering 2016, 142, 04016065 .
AMA StyleAdrian C. H. Lai, S. N. Chan, Wing Keung Adrian Law, E. Eric Adams. Spreading Hypothesis of a Particle Plume. Journal of Hydraulic Engineering. 2016; 142 (12):04016065.
Chicago/Turabian StyleAdrian C. H. Lai; S. N. Chan; Wing Keung Adrian Law; E. Eric Adams. 2016. "Spreading Hypothesis of a Particle Plume." Journal of Hydraulic Engineering 142, no. 12: 04016065.
A new model for assessing the behavior of sediment clouds due to open-water disposal from barges is presented. The model takes into account the realistic physical condition in which the disposed sediments, due to the large and finite amount of sediments typically carried by the barge, will initially descend as a sediment plume (as if from a continuous release) and then transit into a discrete sediment cloud (as if from an instantaneous release) after the barged sediments are fully discharged. These aspects are not represented in existing models so far. The model also includes the geometrical factors of the barge, which can significantly affect the source conditions and thus the subsequent descent process. Two types of predictions are provided by the model: (1) qualitative predictions of the flow regimes of the sediment clouds along the descending path in the water column, and (2) quantitative predictions of the gross characteristics, such as the penetration rate and growth size of the sediment clouds due to entrainment. An experimental study was also carried out for model verification. The comparison between experimental data and model predictions was satisfactory, whereas predictions with the existing models were found to be inadequate due to their oversimplified representations. Similar conclusions were also drawn in the comparison between available field data and model predictions.
Jenn Wei Er; Wing Keung Adrian Law; E. Eric Adams; Bing Zhao. Open-Water Disposal of Barged Sediments. Journal of Waterway, Port, Coastal, and Ocean Engineering 2016, 142, 04016006 .
AMA StyleJenn Wei Er, Wing Keung Adrian Law, E. Eric Adams, Bing Zhao. Open-Water Disposal of Barged Sediments. Journal of Waterway, Port, Coastal, and Ocean Engineering. 2016; 142 (5):04016006.
Chicago/Turabian StyleJenn Wei Er; Wing Keung Adrian Law; E. Eric Adams; Bing Zhao. 2016. "Open-Water Disposal of Barged Sediments." Journal of Waterway, Port, Coastal, and Ocean Engineering 142, no. 5: 04016006.
We present an experimental study of particle plumes in ambient stratification and a mild current. In an inverted framework, the results describe the fate of oil droplets released from a deep ocean blowout. A continuous stream of dense glass beads was released from a carriage towed in a salt-stratified tank. Non-dimensional particle slip velocity UN ranged from 0.1 to 1.9, and particles with UN <= 0.5 were observed to enter the intrusion layer. The spatial distributions of beads, collected on a bottom sled towed with the source, present a Gaussian distribution in the transverse direction and a skewed distribution in the along-current direction. Dimensions of the distributions increase with decreasing UN. The spreading relations can be used as input to far-field models describing subsequent transport of particles or, in an inverted framework, oil droplets. The average particle settling velocity, Uave, was found to exceed the individual particle slip velocity, Us, which is attributed to the initial plume velocity near the point of release. Additionally, smaller particles exhibit a “group” or “secondary plume” effect as they exit the intrusion as a swarm. The secondary effect becomes more prominent as UN decreases, and might help explain observations from the 2000 Deep Spill field experiment where oil was found to surface more rapidly than predicted based on Us. An analytical model predicting the particle deposition patterns was validated against experimental measurements, and used to estimate near-field oil transport under the Deepwater Horizon spill conditions, with/without chemical dispersants. This article is protected by copyright. All rights reserved.
Dayang Wang; E. Eric Adams. Intrusion dynamics of particle plumes in stratified water with weak crossflow: Application to deep ocean blowouts. Journal of Geophysical Research: Oceans 2016, 121, 3820 -3835.
AMA StyleDayang Wang, E. Eric Adams. Intrusion dynamics of particle plumes in stratified water with weak crossflow: Application to deep ocean blowouts. Journal of Geophysical Research: Oceans. 2016; 121 (6):3820-3835.
Chicago/Turabian StyleDayang Wang; E. Eric Adams. 2016. "Intrusion dynamics of particle plumes in stratified water with weak crossflow: Application to deep ocean blowouts." Journal of Geophysical Research: Oceans 121, no. 6: 3820-3835.
We compare oil spill model predictions for a prototype subsea blowout with and without subsea injection of chemical dispersants in deep and shallow water, for high and low gas-oil ratio, and in weak to strong crossflows. Model results are compared for initial oil droplet size distribution, the nearfield plume, and the farfield Lagrangian particle tracking stage of hydrocarbon transport. For the conditions tested (a blowout with oil flow rate of 20,000 bbl/d, about 1/3 of the Deepwater Horizon), the models predict the volume median droplet diameter at the source to range from 0.3 to 6mm without dispersant and 0.01 to 0.8 mm with dispersant. This reduced droplet size owing to reduced interfacial tension results in a one to two order of magnitude increase in the downstream displacement of the initial oil surfacing zone and may lead to a significant fraction of the spilled oil not reaching the sea surface.
Scott A. Socolofsky; E. Eric Adams; Michel C. Boufadel; Zachary M. Aman; Øistein Johansen; Wolfgang J. Konkel; David Lindo; Mads N. Madsen; Elizabeth W. North; Claire B. Paris; Dorte Rasmussen; Mark Reed; Petter Rønningen; Lawrence H. Sim; Thomas Uhrenholdt; Karl G. Anderson; Cortis Cooper; Tim J. Nedwed. Intercomparison of oil spill prediction models for accidental blowout scenarios with and without subsea chemical dispersant injection. Marine Pollution Bulletin 2015, 96, 110 -126.
AMA StyleScott A. Socolofsky, E. Eric Adams, Michel C. Boufadel, Zachary M. Aman, Øistein Johansen, Wolfgang J. Konkel, David Lindo, Mads N. Madsen, Elizabeth W. North, Claire B. Paris, Dorte Rasmussen, Mark Reed, Petter Rønningen, Lawrence H. Sim, Thomas Uhrenholdt, Karl G. Anderson, Cortis Cooper, Tim J. Nedwed. Intercomparison of oil spill prediction models for accidental blowout scenarios with and without subsea chemical dispersant injection. Marine Pollution Bulletin. 2015; 96 (1-2):110-126.
Chicago/Turabian StyleScott A. Socolofsky; E. Eric Adams; Michel C. Boufadel; Zachary M. Aman; Øistein Johansen; Wolfgang J. Konkel; David Lindo; Mads N. Madsen; Elizabeth W. North; Claire B. Paris; Dorte Rasmussen; Mark Reed; Petter Rønningen; Lawrence H. Sim; Thomas Uhrenholdt; Karl G. Anderson; Cortis Cooper; Tim J. Nedwed. 2015. "Intercomparison of oil spill prediction models for accidental blowout scenarios with and without subsea chemical dispersant injection." Marine Pollution Bulletin 96, no. 1-2: 110-126.
This paper explores the effects of droplet size on droplet intrusion and subsequent transport in sub-surface oil spills. In an inverted laboratory set-up, negatively buoyant glass beads were released continuously into a quiescent linearly stratified ambient to simulate buoyant oil droplets in a rising multiphase plume. Settled particles collected from the bottom of the tank exhibited a radial Gaussian distribution, consistent with their having been vertically well mixed in the intrusion layer, and a spatial variance that increased monotonically with decreasing particle size. A new typology was proposed to describe plume structure based on the normalized particle slip velocity \(U_{N} =u_s /(BN)^{1/4}\) , where \(u_s \) is the particle slip velocity, \(B\) is the plume’s kinematic buoyancy flux, and \(N\) is the ambient stratification frequency. For \(U_N \le 1.4\) particles detrain from the plume, but only those with smaller slip velocity \((U_N \le 0.3)\) intrude. An analytical model assuming well-mixed particle distributions within the intrusion layer was derived to predict the standard deviation of the particle distribution, \(\sigma _r =\sqrt{\frac{0.9-0.38(U_N )^{0.24}}{\pi }}\frac{B^{3/8}}{N^{5/8}u_s ^{1/2}}\) and predictions were found to agree well with experimental values of \(\sigma _{r}\) . Experiments with beads of multiple sizes also suggested that the interaction between two particle groups had minimal effect on their radial particle spread. Because chemical dispersants have been used to reduce oil droplet size, this study contributes to one measure of dispersant effectiveness. Results are illustrated using conditions taken from the ‘Deep Spill’ field experiment and the recent Deepwater Horizon oil spill.
Godine Kok Yan Chan; Aaron C. Chow; E. Eric Adams. Effects of droplet size on intrusion of sub-surface oil spills. Environmental Fluid Mechanics 2014, 15, 959 -973.
AMA StyleGodine Kok Yan Chan, Aaron C. Chow, E. Eric Adams. Effects of droplet size on intrusion of sub-surface oil spills. Environmental Fluid Mechanics. 2014; 15 (5):959-973.
Chicago/Turabian StyleGodine Kok Yan Chan; Aaron C. Chow; E. Eric Adams. 2014. "Effects of droplet size on intrusion of sub-surface oil spills." Environmental Fluid Mechanics 15, no. 5: 959-973.
A round thermal is formed when an element of buoyant fluid is released instantaneously into a quiescent ambient. Although the thermal spreading rate is of primary importance to mathematical modeling, the reported values in the literature vary greatly. To identify possible factors affecting the thermal spreading rate, we investigated the effect of different initial conditions numerically by solving the unsteady Reynolds-averaged Navier–Stokes equations with a two-equation turbulence closure. The initial aspect ratio (i.e. length-to-diameter ratio) of the thermal was varied between 0.125–4.0, and the initial density differences was changed from 1 to 10 %. Results show that the spreading rate is greatly affected by the initial aspect ratio, which also explains the variations in earlier reported values. Following the numerical study, an analytical model using buoyant vortex ring theory is developed to predict the spreading rate of a thermal. The predictions show good agreement with the results from both the numerical simulations and previous experimental studies. Another simple analytical model is also presented to approximate the thermal induced flow, and is validated using the numerical simulations.
Adrian C. H. Lai; Bing Zhao; Adrian Wing-Keung Law; E. Eric Adams. A numerical and analytical study of the effect of aspect ratio on the behavior of a round thermal. Environmental Fluid Mechanics 2014, 15, 85 -108.
AMA StyleAdrian C. H. Lai, Bing Zhao, Adrian Wing-Keung Law, E. Eric Adams. A numerical and analytical study of the effect of aspect ratio on the behavior of a round thermal. Environmental Fluid Mechanics. 2014; 15 (1):85-108.
Chicago/Turabian StyleAdrian C. H. Lai; Bing Zhao; Adrian Wing-Keung Law; E. Eric Adams. 2014. "A numerical and analytical study of the effect of aspect ratio on the behavior of a round thermal." Environmental Fluid Mechanics 15, no. 1: 85-108.
In the literature, it has been conceptualized that a group of dense particles released instantaneously into homogeneous stagnant water would form a circulating vortex cloud and descend through the water column as a thermal. However, Wen & Nacamuli (Hydrodynamics: Theory and Applications, 1996, pp. 1275–1280) observed the formation of particle clumps characterized by a narrow, fast-moving core shedding particles into the wake. They found clump formation to be possible even for particles in the non-cohesive range as long as the source Rayleigh number was large ( $\mathit{Ra} > {10^3}$ ) or, equivalently, the source cloud number was small ( $\mathit{Nc} ). This physical phenomenon has not been investigated further since the experiments of Wen and Nacamuli. In the present study, the relationship between Nc and the formation process is examined more systematically. The theoretical support for cloud number dependence is explored by considering flows passing a porous sphere. Here $\mathit{Nc}$ values ranging from $2.9 \times 10^{-3}$ to $5.9 \times 10^{-2}$ are tested experimentally using particles with different initial masses and grain sizes, from non-cohesive to marginally cohesive. The formation processes are categorized into cloud formation, a transitional regime and clump formation, and their distinct features are presented through qualitative description of the flow patterns and quantitative assessment of the gross characteristics.
B. Zhao; Wing Keung Adrian Law; E. E. Adams; J. W. Er. Formation of particle clouds. Journal of Fluid Mechanics 2014, 746, 193 -213.
AMA StyleB. Zhao, Wing Keung Adrian Law, E. E. Adams, J. W. Er. Formation of particle clouds. Journal of Fluid Mechanics. 2014; 746 ():193-213.
Chicago/Turabian StyleB. Zhao; Wing Keung Adrian Law; E. E. Adams; J. W. Er. 2014. "Formation of particle clouds." Journal of Fluid Mechanics 746, no. : 193-213.
Miscible thermals are formed by instantaneously releasing a finite volume of buoyant fluid into stagnant ambient. Their subsequent motion is then driven by the buoyancy convection. The gross characteristics (e.g. overall size and velocity) of a thermal have been well studied and reported to be self-similar. However, there have been few studies concerning the internal structure. Here, turbulent miscible thermals (with initial density excess of 5 % and Reynolds number around 2100) have been investigated experimentally through a large number of realizations. The vorticity and density fields were quantified separately by particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques. Ensemble-averaged data of the transient development of the miscible thermals are presented. Major outcomes include: (i) validating Turner’s assumption of constant circulation within a buoyant vortex ring; (ii) measuring the vorticity and density distributions within the miscible thermal; (iii) quantifying the effect of baroclinicity on the generation and destruction of vorticity within the thermal; and (iv) identifying the significantly slower decay rate of the peak density as compared to the mean.
B. Zhao; Wing Keung Adrian Law; A. C. H. Lai; E. E. Adams. On the internal vorticity and density structures of miscible thermals. Journal of Fluid Mechanics 2013, 722, 1 .
AMA StyleB. Zhao, Wing Keung Adrian Law, A. C. H. Lai, E. E. Adams. On the internal vorticity and density structures of miscible thermals. Journal of Fluid Mechanics. 2013; 722 ():1.
Chicago/Turabian StyleB. Zhao; Wing Keung Adrian Law; A. C. H. Lai; E. E. Adams. 2013. "On the internal vorticity and density structures of miscible thermals." Journal of Fluid Mechanics 722, no. : 1.
A sediment cloud release in stagnant ambient fluid occurs in many engineering applications. Examples include land reclamation and disposal of dredged materials. The detailed modeling of the distinct characteristics of both the solid and fluid phases of the sediment cloud is hitherto unavailable in the literature despite their importance in practice. In this paper, the two-phase mixing characteristics of the sediment cloud are investigated both experimentally and theoretically. Experiments were carried out to measure the transient depth penetration and the lateral spread of the sediment cloud and its entrained fluid using the laser induced fluorescence technique, with a range of particle sizes frequently encountered in the field (modeled at laboratory scale). A two-phase model of the sediment cloud that provides detailed predictions of the mixing characteristics of the individual phases is also proposed. The entrained fluid characteristics are solved by an integral model accounting for the buoyancy loss (due to particle separation) in each time step. The flow field induced by the sediment cloud is approximated by a Hill’s spherical vortex centered at the centroid and with the size of the entrained fluid. The particle equation of motion under the effect of the induced flow governs each computational particle. A random walk model using the hydrodynamic diffusion coefficient is used to account for the random fluctuation of particles in the dispersive regime. Overall, the model predictions of the two-phase mixing characteristics are in good agreement with the experimental data for a wide range of release conditions.Singapore. National Research Foundation ( Singapore-MIT Alliance for Research and Technology’s CENSAM IRG research programme
Adrian C. H. Lai; Bing Zhao; Wing Keung Adrian Law; E. Eric Adams. Two-phase modeling of sediment clouds. Environmental Fluid Mechanics 2013, 13, 435 -463.
AMA StyleAdrian C. H. Lai, Bing Zhao, Wing Keung Adrian Law, E. Eric Adams. Two-phase modeling of sediment clouds. Environmental Fluid Mechanics. 2013; 13 (5):435-463.
Chicago/Turabian StyleAdrian C. H. Lai; Bing Zhao; Wing Keung Adrian Law; E. Eric Adams. 2013. "Two-phase modeling of sediment clouds." Environmental Fluid Mechanics 13, no. 5: 435-463.
Flow visualization experiments were performed in a glass-walled recirculating flume to observe the fate of sediments released instantaneously in a current. For releases at the surface, criteria were developed to characterize ambient currents as “weak,” “transitional,” or “strong” as a function of particle size. In weak ambient currents, particle clouds were advected downstream with a velocity equal to the ambient current, but otherwise their behavior and structure were similar to those in quiescent conditions. A substantial portion of the mass initially released, up to 30%, was not incorporated into the parent cloud and formed the trailing stem. This percentage was dependent on the initial release variables, with the greatest sensitivity on particle size. The “loss” of sediment during descent, defined as the fraction of mass missing a designated target with a radius equal to the water depth, was quantified and found to increase sharply with current speed. Laws of geometric, kinematic, and dynamic similitude provide a basis for scaling laboratory results to the real world and formulating guidelines to reduce the losses that could result from open-water sediment disposal.
R. James Gensheimer; E. Eric Adams; Wing Keung Adrian Law. Dynamics of Particle Clouds in Ambient Currents with Application to Open-Water Sediment Disposal. Journal of Hydraulic Engineering 2013, 139, 114 -123.
AMA StyleR. James Gensheimer, E. Eric Adams, Wing Keung Adrian Law. Dynamics of Particle Clouds in Ambient Currents with Application to Open-Water Sediment Disposal. Journal of Hydraulic Engineering. 2013; 139 (2):114-123.
Chicago/Turabian StyleR. James Gensheimer; E. Eric Adams; Wing Keung Adrian Law. 2013. "Dynamics of Particle Clouds in Ambient Currents with Application to Open-Water Sediment Disposal." Journal of Hydraulic Engineering 139, no. 2: 114-123.
In this study, the underwater behaviour of sediment thermals (i.e. sediment clouds in the self-preserving phase), formed by releasing dry sediments instantaneously from various heights above water, was investigated experimentally. Measurements show that as the air release height increases, the initial acceleration phase of the sediment cloud in water is shortened, while the growth rate during its self-preserving phase remains constant. Therefore, the effect of air release height can be accounted for by utilizing a new concept of simultaneous virtual distance and time origins, which are found to be related to an impact densimetric Froude number (defined as the ratio between the impact velocity of the sediment cluster at the water surface and the characteristic velocity of the sediment thermal generated by buoyancy excess). Based on the measurement results, a semi-empirical model is utilized to predict the growth and penetration behaviours of the sediment thermal. Predictions by the model with the virtual origins correction match well with the experimental data.
Bing Zhao; Wing Keung Adrian Law; E. Eric Adams; Dongdong Shao; Zhenhua Huang. Effect of air release height on the formation of sediment thermals in water. Journal of Hydraulic Research 2012, 50, 532 -540.
AMA StyleBing Zhao, Wing Keung Adrian Law, E. Eric Adams, Dongdong Shao, Zhenhua Huang. Effect of air release height on the formation of sediment thermals in water. Journal of Hydraulic Research. 2012; 50 (5):532-540.
Chicago/Turabian StyleBing Zhao; Wing Keung Adrian Law; E. Eric Adams; Dongdong Shao; Zhenhua Huang. 2012. "Effect of air release height on the formation of sediment thermals in water." Journal of Hydraulic Research 50, no. 5: 532-540.