Modeling Sediment Flocculation in Langmuir Turbulence

Abstract

Cohesive sediments exist as flocs of different sizes, which are built and destroyed through flocculation processes including both aggregation and breakup. This study investigates sediment flocculation processes in wave-driven Langmuir turbulence that is commonly observed in coastal ocean through embedding a size-resolving flocculation model into a turbulence-resolving hydrodynamic model. The specific research questions are how Langmuir turbulence affects flocculation processes and how flocculation processes impact the spatial and size distributions of suspended cohesive sediment. The results show that Langmuir turbulence suspends flocs in the water column and organizes flocs of different sizes. By modulating the encounter of flocs and redistributing flocs in the turbulence field, Langmuir turbulence enhances the aggregation and breakup rates of flocs that are located in similar regions with high turbulent dissipation rates and suppresses those of others. As an outcome of modulated flocculation processes, floc size distribution changes with depth and floc mass concentration profiles change with floc size. The addition of wave breaking increases the shear rate near the surface and reduces the median floc size and averaged settling velocity, leading to increase in total floc mass concentration in the whole water column. Wave breaking also increases cross-shelf sediment transport by more than 15% under the simulated conditions, which is comparable to that due to Langmuir turbulence compared to shear turbulence. Both floc size distribution and floc concentration vary with wind and wave conditions. Key Points:• A size-resolving floc model embedded in a large eddy simulation model is used to study flocculation in shallow-water Langmuir turbulence • Flocculation processes modify vertical mean concentration profiles for flocs of a certain size • Langmuir turbulence modulates aggregation and breakup rates Supporting Information:• Supporting Information S1

Emerging investigator series: impacts of aeration flow rates and bubble sizes on PFOA/PFOS removal in electrocoagulation

“…of metal flocs. 30,31 Previous EC studies reported smaller BET surface areas (19.8–84.1 m 2 g −1 ) of zinc hydroxide floc generated by EC than the present study. 14,32,33 The difference is likely due to the different aeration conditions, a different configuration of the EC reactor, different initial pH, and the presence of different dissolved ions in the solution.…”

Abundant novel wave solutions of nonlinear Klein–Gordon–Zakharov (KGZ) model

“…The matching between the analytical and numerical solutions has been illustrated through some various figures (Figs. 1,2,3,4,5,6). The applied numerical method's performance shows its powerful and effective for studying the numerical solutions of some nonlinear evolution equations.…”

“…This magnitude is based totally on its achievement according to supplying a profitable probability in conformity with overmatch the concentration Problem within Langmuir [3,4]. The concentration trap in Langmuir is attributable according to the enlarge within the number concerning long-wave disruptions between who the vibrance do no longer stay damped by means of Landau yet radiation; the connection together with the coulomb at intense instances is similarly incapable of airing the smearing editions within the oscillations because concerning their frequency [5][6][7]. Plasma sickness has grown to be a regime over extreme longevity up to expectation approves condensing fluctuations in imitation of remain released, addresses the trouble regarding the Langmuir turbulence power a e-mail: mostafa.khater2024@yahoo.com (corresponding author) 0123456789().…”

A comparison study on the sediment flocculation process between a bare tidal flat and a clam aquaculture mudflat: The important role of sediment concentration and biological processes

“…The effect of differential settling on the aggregation process is relatively greater in weak turbulence regions, for example, still water in laboratory experiments (Wendling et al, 2015) and estuarine and coastal environments during slack waters (Christie et al, 1999;Guo et al, 2017;Guo et al, 2018;Milligan et al, 2007). Of these three principle particle collision mechanisms, fluid shear is the dominant mechanism that drives particle collision in energetic flows (Liu et al, 2019;Manning, 2004;McAnally William and Mehta Ashish, 2000). Other factors can also influence the particle collision, such as suspended sediment concentration (SSC) (Manning, 2004;Mhashhash et al, 2018;Razaz et al, 2015;Tran et al, 2018;Van der Lee, 2000).…”