Simulation of vertical dispersion of oil droplets by Langmuir supercells through a Reynolds-averaged Eulerian formulation combined with Lagrangian particle tracking

Perez, Anthony; Cui, Fangda; Peñaloza-Gutierrez, J.; Zeidi, Seyedmohammadjavad; Sinha, Nityanand; Boufadel, Michel C.; Smith, Carlowen Andrew; Murphy, David; Tejada-Martínez, Andrés

doi:10.1016/j.oceaneng.2021.109043

Cited by 2 publications

(6 citation statements)

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“…Such findings imply that the use of dispersants during oil spills, which facilitate the generation of smaller oil droplets, and the wind strength, which determines LC strength, can significantly affect subsurface oil dispersion, retention, and dilution. However, some discrepancies exist between our experiments and the simulations done by Perez et al (2021). For example, in our experiments, oil droplets are retained for at least 10 min (though the oil concentration at this time is quite small; Fig.…”

Section: Discussioncontrasting

confidence: 99%

“…For example, models of the subsurface behavior of air bubbles under the influence of LC developed by Thorpe (1984) suggest that smaller air bubbles reach greater depths than larger bubbles. Similarly, simulations of oil droplet behavior in SRZs suggest that oil droplets have greater dispersion under higher wind shear forcing which results in greater circulation strength (Perez et al 2021). In particular, smaller oil droplets (~ 1 to few 100 μ m) have a greater tendency to distribute more widely across Langmuir cells, reach greater depths, and undergo more dilution than larger oil droplets (Farmer and Li 1994; Yang et al 2014).…”

Section: Discussionmentioning

confidence: 97%

“…For example, one reason for the observed difference in oil droplet spatial distribution could be that the wider turbulent downwelling region in the simulations transports a greater number of droplets downwards whereas the thinner downwelling region in the experiments allows a greater number of droplets to escape sideways into the vortex center. The greater spatial scale of the simulations also likely explains the longer oil droplet residence times, though the selected value of the turbulence model coefficient ( C L = 0.15), which greatly affects particle dispersion, could also play a role (Perez et al 2021).…”

Section: Discussionmentioning

confidence: 99%

“…LC strength is parameterized by the turbulent Langmuir number

{La}_{t} = {((), \frac{u_{*}}{U_{s 0}})}^{\frac{true}{1}}

, which represents the ratio between wind forcing as represented by the wind stress friction velocity

u_{*} = {((), \frac{τ_{wind}}{ρ})}^{\frac{true}{1}}

(where

τ_{wind}

and ρ are the wind shear stress and seawater density, respectively) and wave forcing as represented by the surface Stokes drift velocity U s0 (McWilliams et al 1997; McWilliams and Sullivan 2000). Typical values of

{La}_{t}

are 0.2–0.5 for the ocean (McWilliams et al 1997; McWilliams and Sullivan 2000; Thorpe 2004; Belcher et al 2012) and somewhat larger (e.g., 0.5–0.7) in shallower coastal waters (Gargett and Wells 2007; Perez et al 2021). LC also affects other processes, such as surface layer mixing (Thorpe 2004; Flór et al 2010), oil spill spreading (Liu and Sheng 2014; Simecek‐Beatty and Lehr 2017), sediment resuspension (Gargett et al 2004; Gargett and Wells 2007), and horizontal transport of buoyant particles (Kukulka 2020).…”

Section: Figmentioning

confidence: 99%

“…A similar 2D configuration also appears in numerical work such as Farmer and Li (1994) who studied oil droplet dispersion in Langmuir cells. More recently, Perez et al (2021) similarly investigated the dispersion of oil droplets by Langmuir supercells using a combination of three‐dimensional (3D) Reynolds‐averaged Navier–Stokes (RANS) simulations and Lagrangian particle tracking. In the current study, we describe a newly developed laboratory‐scale experimental facility that produces SRZs and use it to study the behavior and fate of oil droplets in LC.…”

Section: Figmentioning

confidence: 99%

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An experimental Stommel Retention Zone facility with an application to oil droplet dispersion

Gurung

Smith

Zeidi

et al. 2022

Limnology & Ocean Methods

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Stommel Retention Zones (SRZs) associated with wind-driven Langmuir circulation (LC) facilitate the subsurface retention of particles and thus affect processes such as oil spill dispersion, sediment suspension, oil-particle aggregation, and plankton distribution. Since the effect of SRZs on these processes is difficult to study in the field, we present a novel laboratory facility designed to recreate the counterrotating vortex pair flow pattern associated with small-scale SRZs of various strengths in two dimensions (2D). We then inject an oil jet into this facility to study buoyant oil droplet retention in these SRZs. 2D particle image velocimetry and hybrid Reynolds-averaged Navier-Stokes/large eddy simulation are used to characterize the flow. Large-scale oil droplet trajectories in the SRZs are visualized, and oil droplet statistics in the downwelling region and vortex core are measured using high-magnification brightfield imaging and a droplet detection algorithm. Values of maximum velocity (7.7-32.2 mm s À1 ), turbulent kinetic energy (10 À6 to 10 À4 m 2 s À2 ), and turbulent kinetic energy dissipation rate (10 À7 to 10 À5 m 2 s À3 ) in the downwelling region of the facility fall within the range of values observed in the field. Flow field strength strongly influences oil droplet trajectories, the shape and size of the SRZ, and oil droplet statistics over time, with stronger flows retaining larger oil droplets in the downwelling region over longer periods of time. Indeed, droplets of almost 400 μm diameter are observed in the downwelling region after almost 10 min for the strongest flow. The facility may be used to study the behavior of microplastics, sediments, and zooplankton in LC in the future.

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Section: Discussioncontrasting

confidence: 99%