Lagrangian Particle Tracking Model Research Articles

A Larval “Recruitment Kernel” to Predict Hatching Locations and Quantify Recruitment Patterns

AbstractLarval recruitment, a critical component of population connectivity, has been under investigated compared to larval dispersal. We developed a backward‐in‐time Lagrangian particle tracking model to predict larval hatching locations and proposed a larval recruitment kernel, to quantify recruitment patterns. Combining field data and a hydrodynamic model, our backtracking model predicted Lake Whitefish (Coregonus clupeaformis) hatching locations in Lake Erie. We found a strong linear correlation (r = 0.95–0.98) between travel distance (i.e., distance along a trajectory) and pelagic larval duration (PLD), and a moderate correlation (r = 0.66–0.68) between linear distance (i.e., displacement) and PLD. This questions the wide use of PLD as a proxy for dispersal distance. We defined the recruitment kernel using the probability density function of the linear recruitment distance. Characteristics of the recruitment kernel, such as theoretical self‐recruitment, median‐recruitment distance, long‐distance recruitment, and openness convey significant information about population connectivity that are distinct from those derived using the well‐known dispersal kernel (e.g., theoretical local retention).

Larval dispersal and climate models provide insights into present and future distribution of a tropical sardine

ABSTRACT Climate change impacts the distribution of marine organisms and threatens fisheries. Marine protected areas (MPAs) may buffer the detrimental effects of environmental change by acting as biodiversity spillover to neighboring areas. Yet, it is uncertain whether MPAs on islands favor passive dispersal of species through oceanic currents, and how fish abundance and distribution will be impacted by ongoing global warming. Using the Brazilian-endemic scaled-sardines (Harengula sp.) as model, we implemented a Lagrangian particle-tracking model to estimate dispersal in the Brazilian coast and four MPAs in islands. Then, we projected an ecological niche model (ENM) of Harengula sp. to three climatic scenarios in 2100. Dispersal models suggested that three MPAs in islands export eggs and larvae acting as source of biomass to the coast. ENMs indicated a decrease in environmental suitability for Harengula sp. at the Equatorial Brazilian coast and a southward shift that increases as the climatic scenario is aggravated. Ocean warming may lead to a decrease in suitability for Harengula sp. in the northernmost part of its current distribution concomitant with an increase in offshore zones in the south of its current distribution. Ecosystem disturbance with environmental suitability shifts can aggravate the isolation of populations in islands.

Effectiveness of portable air cleaners in mitigating respiratory virus transmission risk

Portable air cleaners (PACs) have shown promising potential in reducing the risk of SARS-CoV-2 infection by effectively removing pollutant particles and optimizing airflow patterns. This study focused on a simulated scenario where an infected source and a susceptible person engage in conversation within a naturally ventilated room. By combining the Eulerian fluid method with the Lagrangian particle tracking model, a comprehensive insight into indoor airflow patterns and the dispersion of virus-laden droplets was gained. As deposited droplets may be resuspended or in contact thereby increasing the potential risk of infection, the deposition of droplets of different sizes in different susceptible areas was also specifically analyzed. The impacts of three variables, namely the configuration of the PAC’s opening, air flow rate, and positioning, on the transmission of virus-laden droplets were investigated. The results highlighted the significant role of PAC utilization in effectively capturing droplets emitted by the infected source and reducing virus concentration in the vicinity of the susceptible person, thereby mitigating the risk of transmission. Notably, the design and orientation of the suction opening emerged as crucial factors. Among the various cases studied, the optimal control and prevention performance against the virus was achieved with a virus concentration reduction rate of 97.4% when the PAC had an opening configuration with a larger single-sided suction opening facing the infected source, an airflow rate of 200 m3 h−1, and was positioned at the center of the tabletop between the infected source and the susceptible person. This research underscored the importance of employing PACs with appropriate settings to enhance indoor air quality and minimize the potential for SARS-CoV-2 transmission in similar scenarios.

Short-term buoyant microplastic transport patterns driven by wave evolution, breaking, and orbital motion in coast

Recently, there has been a notable rise in social and scientific interest regarding microplastic pollution in coasts where waves significantly influence flow patterns and material transport. This study explores typical short-term movement of buoyant microplastics driven by surf zone processes including wave transformation, breaking, and orbital motion. To track microplastics, Lagrangian Particle Tracking Model (PTM) coupled with Eulerian wave-current interaction model appropriate for coastal hydrodynamics was used. From the simulations, several important findings were observed. (i) In alongshore uniform beaches, lighter and larger buoyant microplastics tended to reach beach more readily. (ii) Accurate predictions of microplastic transport in the surf zone required the consideration of wave breaking. (iii) In alongshore non-uniform coastal bathymetry, rip-currents can send buoyant microplastics offshore, beyond the surf zone.

Case Study of Contaminant Transport Using Lagrangian Particle Tracking Model in a Macro-Tidal Estuary

This study presents a comprehensive analysis of contaminant transport in estuarine environments, focusing on the impact of tidal creeks and flats. The research employs advanced hydrodynamic models with irregular grid systems and conducts a detailed residual current analysis to explore how these physical features influence the movement and dispersion of contaminants. The methodology involves simulating residual currents and Lagrangian particle trajectories in both ‘Creek’ and ‘No Creek’ cases, under varying tidal conditions. The results indicate that tidal creeks significantly affect particle retention and transport, with notable differences observed in the dispersion patterns between the two scenarios. The ‘Creek’ case demonstrates enhanced material retention along the creek pathways, while the ‘No Creek’ case shows broader dispersion, potentially leading to increased sedimentation in open sea areas. The discussion highlights the implications of these findings for sediment dynamics, contaminant transport, and estuarine ecology, emphasizing the role of tidal creeks in modulating flow and material transport. The research underlines the necessity of incorporating detailed environmental features in estuarine models for accurate contaminant transport prediction and effective estuarine management. This study contributes to a deeper understanding of estuarine hydrodynamics and offers valuable insights for environmental policy and management in coastal regions.

Distribution and Environmental Impact of Expanded Polystyrene Buoys from Korean Aquaculture Farms

Expanded polystyrene (EPS) buoys, commonly employed in South Korean aquaculture farms, are prone to fragmentation, generating substantial marine debris. The trajectories of EPS buoys dislocated from aquaculture farms were investigated using a Lagrangian particle-tracking model. Daily ocean current data from the 1/12° Hybrid Coordinate Ocean Model analysis and wind data from the 1/4° European Center for Medium-Range Weather Forecasts reanalysis were used as inputs. The particles were released daily, and the initial positions and number of particles were determined based on the usage of EPS buoys. Because EPS buoys are highly buoyant, both wind and ocean currents considerably influence their movement. To account for variations in the buoyancy of these buoys, three experiments were conducted, each considering different levels of windage. The simulation results closely aligned with the observed coastal distribution patterns of the large EPS debris. As the windage increases, the particles exhibit a swifter deviation from their original locations, highlighting the need for effective local management. Moreover, this increased windage affects the distribution patterns in regional seas, reducing the number of particles that flow into the East Sea, while increasing the number of particles that migrate into the Yellow Sea and East China Sea.

Larval Dispersal Modelling of the Blue Swimming Crab Portunus pelagicus (Linnaeus, 1758) from the Crab Banks along the Coast of Trang Province, Southern Thailand

In Thailand, the populations of a commercially important crab Portunus pelagicus (Linnaeus, 1758) have been decreasing due to overfishing, raising concerns about the conservation efforts of this crab species. The Crab Bank Project has recently been established to restore crab populations by releasing crab larvae from each crab bank station. However, the fate of crab larvae after the release is poorly understood. Here, we assessed the dispersal and settlement patterns of the larvae P. pelagicus released from crab banks along the coast of Trang Province, Southern Thailand. The Lagrangian particle tracking model was employed to simulate the larval dispersal and settlement patterns after release from the crab banks during the inter-monsoon, southwest monsoon, and northeast monsoon. Our simulation revealed that virtual larvae were predominantly retained within inshore areas after the release for 14 days, regulated by tidal-driven currents, wind-induced currents, and local coastal topography. Monsoon periods affected the larval dispersal, with some larvae being transported into estuaries due to the SW monsoonal effects. After the 14-day release period, our modelled simulations suggested that the crab larvae arrived at numerous seagrass meadows along the coast, indicating potential settlement and growth. This result highlights the connectivity of sources and sinks for crab larvae after release from crab banks. Moreover, significant implications for conservation efforts and the fishery management of P. pelagicus were also discussed based on our modelled simulations.

Caracterização do transporte de material lenhoso no rio Madeira na Usina Hidrelétrica Jirau: um estudo utilizando um modelo tridimensional de partículas

ABSTRACT The Madeira River is characterized by large amount of woody material transported, especially during floods, which interferes with the operation of the Jirau Hydroelectric Power Plant. There are many logs and the log boom structures inserted to retain them do not always present the desired efficiency. This work involves the hydrodynamic simulation of the Madeira River and the three-dimensional simulation of these woody materials to analyze their trajectories along the river and to obtain knowledge of their transport and position according to the flow, different plant operations ways and the influence of log booms. The logs are simulated as particles by the PART module of Delft3d, using the Lagrangian particle tracking model. The hydrodynamic model was validated and it was possible to represent the main variations of three-dimensional velocities and water levels. The particle tracking simulation was consistent with the flow distribution and thus it was possible to identify the most attractive destination for the logs, according to power plant operations.

MATT’S PATROL: A Generalized framework to track marine litter path, fare and toll

Attention is given to the mapping of marine litter pathways due to their negative impact on the environment, society, and economy. Many models have been created to examine ocean dynamics and particle tracking systems. This study aims to contribute to these existing models by introducing a framework called “MATT’S PATROLL: MArine liTTer’S PATh, faRe, and tOLL.” This framework examines three pillars needed for the management of marine litter, the computational, socio-ecological, and economic arms. The Lagrangian particle tracking model is used to model the spatio-temporal behavior of litters on the surface of the ocean. The “faRe” component describes the direct and indirect effects of meso-particles on sea and land populations while they wait to accumulate on shorelines and other settlements. The “tOLL” component examines the long-term ecological and socio-economic costs on ecosystems in land and water, as well as the damage and loss in gross revenue from the marine sector when marine litters penetrate habitats and livelihoods. To illustrate the framework, artificially generated litter data around Visayas region is used to simulate path, fare, and toll calculations.

Oceanic currents maintain the genetic structure of non-marine coastal taxa in the western Mediterranean Sea

Coastal habitats are amongst the most dynamic on Earth, due to their simultaneous exposure to terrestrial, oceanic and atmospheric processes. Coastal taxa are therefore often ecologically specialised and adapted to withstand frequent shifts in sea level, wave exposure, temperature or salinity. This specialisation often resulting in significant cryptic diversity. Previous molecular studies have suggested that genetic differentiation in non-marine coastal organisms may be influenced by oceanic currents and fronts, but the extent to which such processes affect dispersal and evolution of such taxa remains unclear. Here we explore whether population genetic structure in two supralittoral rockpool beetle species (genus Ochthebius) can be predicted from the general circulation pattern of the marine currents and associated oceanic fronts. We simulated dispersal using a Lagrangian particle tracking model and compared this with population genetic structure inferred from COI (mitochondrial) and wingless (nuclear) genes applying linear models and Mantel tests. We show that a biophysical model based on oceanic currents and fronts in the western Mediterranean Sea is a much better predictor of observed population genetic structure than isolation by distance in both species. Our results show that oceanic processes, besides shaping contemporary population connectivity in fully marine organisms, also exert a meaningful influence on terrestrially-derived coastal taxa such as supralittoral rockpool beetles — the first time this mode of dispersal has been demonstrated in an insect.

Predicting potential spawning areas of European bass, Dicentrarchus labrax, in the Irish and Celtic seas

Marine fish species that form spawning aggregations are often vulnerable to exploitation, such as the European bass (Dicentrarchus labrax). Information on bass spawning aggregations is not well resolved temporally and spatially. Otolith daily growth increment (DGI) counts were conducted on 0-group bass collected in July-August 2014 & 2019 from seven settlement estuaries in the Irish and Celtic seas, to estimate the timing of spawning. These timings parameterised three-dimensional hydrodynamic and Lagrangian particle tracking models, run in reverse, to identify probable spawning locations. Estimated spawning occurred between April-May (inshore and offshore) < 200 km from each settlement area. At least two broad spawning areas were predicted: the central Irish Sea that led to post-larval recruitment in north Wales and northwest England, and the southern Irish Sea/Celtic Sea that led to post-larval recruitment in south Wales. Results indicate the current seasonal closure for northern stock bass may not protect spawning events that drive recruitment into settlement sites in Wales and northwest England. Surface temperatures and wind- and tide-driven surface currents determined the connectivity between spawning and settlement sites. Atmospheric drivers are expected to change in the future and management needs to account for potential regional shifts in spawning times and locations.

Simulating larval dispersal across the distribution of the New Zealand green-lipped mussel: insights into connectivity and source-sink dynamics

Information about population connectivity, including the rates and routes of larval transport as well as source-sink dynamics, is important for the sustainable management of harvested species. For marine species whose primary mode of dispersal is transport during the pelagic larval stage, biophysical modelling of larval dispersal represents a valuable tool that is not subject to some of the same limitations as genetic connectivity analyses. In particular, a model that encompasses the entire distribution of a species can provide novel insights by identifying potentially important source populations or stepping-stone sites from which molecular samples may not be available. This study employed a Lagrangian particle-tracking model to simulate larval releases from all potential mussel habitats along ~15000 km of coastline for an endemic New Zealand bivalve, the green-lipped mussel. A northern and a southern cluster with a break near Cook Strait were identified, confirming the structure reported by earlier genetic analyses and a previous biophysical modelling study. The present study revealed, for the first time, that connectivity between the 2 clusters is largely asymmetrical, with more particle transport from the south to the north. Because this study simulated spawning events across the entire distribution of the species, several previously unknown source populations and stepping-stone populations were identified. These findings highlight the utility of a multidisciplinary approach to understanding marine connectivity and provide evidence for new strategies, including the protection of source and stepping-stone populations, to sustainably manage this endemic species.

Modeling wind-driven seed dispersal using a coupled Lagrangian particle tracking and 1-D [formula omitted]-[formula omitted] turbulence model

We present a one-dimensional k-ɛ model and a Markov chain stochastic Lagrangian particle tracking model to study wind-driven dispersal of forest and grassland seeds. The turbulence model within and above the canopy is implemented for transient winds so that time series of profiles of mean velocity, turbulence kinetic energy, dissipation rate, and the root-mean-square of fluctuating velocity components can be modeled. We validate the model for steady state conditions using observations in a wide range of canopies, and apply the model for predicting time series of seed dispersal of Andropogon gerardii in a tall grass prairie in Missouri, United States. The stochastic seed dispersal model is validated against experimental data from a Quercus-Carya (oak-hickory) forest where seeds were released from different heights for a range of wind speeds. Using the model, we explore the detailed seed movement trajectories, instantaneous velocities, and investigate the relationship between dispersal distance and the seed falling duration and the mean fluctuating velocity during the falling. Moreover, examining the role of individual turbulent velocity components, we elucidate the different roles of horizontal and vertical velocity fluctuations, i.e., the horizontal component mainly contributes to the seed spreading in the wind direction, while the vertical component enhances the long tail of the distribution in the downstream direction, i.e., promoting long-distance-dispersal of seeds by wind.

Origin and pathway of a subsurface maximum of 137Cs detected in the winter of 2012 after the Fukushima accident

This study investigates the dispersion behavior of 137Cs and evaluates its origin (atmospheric deposition or direct ocean release) from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident using a Lagrangian particle tracking model. The ocean circulation fields based on the Modular Ocean Model Version 5 (MOM5) were adopted for the simulation. The MOM5 results represented the formation and migration of subtropical mode water (STMW) comparable with observations and reanalysis data. Particularly, anticyclonic eddies south of the Kuroshio extension promoted surface mixing over 300 m in the cooling season. The particle tracking simulation reproduced well the maximum subsurface activity between 142 and 146°E, where STMW is deep owing to anticyclonic eddies, compared to the activity found via measurements conducted around 149°E in the winter of 2012. It also demonstrated that the 137Cs of the tropical and subtropical regions (10–35°N, 142–146°E) in the winter of 2012 almost entirely originated from atmospheric deposition.

Modelling marine microplastics accumulation zones through freshwater discharge sources: Simulated release from the Onkaparinga River and Torrens River, South Australia

Plastic pollution is fast becoming one of the most prominent contamination issues facing the marine environment. Microplastics are a major subset of plastic waste now present in all global oceans, with their numbers standing only to increase. This study applies a coupled hydrodynamic model and Lagrangian particle-tracking model to predict and simulate microplastic transport in South Australian waters. Virtual particles representing microplastics were released daily for 365 days from two major freshwater input sources along the coastline of Adelaide, Australia. These particles entered the Gulf St Vincent and were tracked over two model years using LTRANS software. The model identified general gulf circulation as circular, clockwise, with net southward particle transport from particle release sites. A potential accumulation zone associated with a local eddy was identified. Concentrations of particles that passed through local marine parks were also calculated in response to the potential concerns they pose in vulnerable protected areas.

How does buoyancy behavior impact microplastic transport in an estuarine environment?

Much is still unknown about the transport behavior of microplastic pollutants within the marine environment, particularly smaller scale coastal systems such as estuaries. Through the use of a Lagrangian particle-tracking model coupled with a validated 3D hydrodynamic model, we examined the transport, pathway and ultimate fate of microplastic particles, both in an idealized estuary and Galveston Bay, Texas, USA. Emphasis was placed on differences based on settling behavior (neutrally versus negatively buoyant), use of random walk for diffusion processes, and release location. For Galveston Bay, settling behavior had a noteworthy impact on both the transport pathway of microplastic particles, as well as overall time spent within the bay. Particles with negative buoyancy were retained approximately seven times longer than those with neutral buoyancy. Negatively buoyant particles also showed a tendency to be dispersed eastward to Trinity Bay through the bottom baroclinic flow, while neutrally buoyant particles took a more direct route along the ship channel to the mouth of the bay. Idealized model simulations suggest impact of settling depends on the vertical mixing strength. For a system with stronger tidal mixing, negatively buoyant particles with small settling velocities may still behave similarly to neutrally buoyant particles, and differences only become apparent for particles that sink rather quickly (> 10 m d−1). Future sea-level rise or channel deepening tends to flush out neutrally buoyant particles more quickly, while increasing the retention time for negatively buoyant particles. Our results suggest that plastics within estuaries could show substantially different behavior depending on their buoyancy characteristics, highlighting a need to quantify specific settling velocities of plastic pollutants entering the coastal estuarine system.

Tracking the pumice rafts from the Fukutoku-Okanoba submarine volcano with Satellites and a Lagrangian Particles trajectory model

On August 13th, 2021, the Fukutoku-Okanoba, a submarine volcano in the Northwest Pacific Ocean, erupted. Satellites detected various pumice rafts that had drifted westward to reach southern Japan over two months. To cope with the potential danger from pumice rafts, predicting their trajectories is crucial. Using a Lagrangian particle tracking model, the trajectories of the rafts were investigated. The model results showed strong sensitivity to the windage coefficient of pumice rafts, which is uncertain and could cause significant errors. An optimal windage coefficient was estimated by comparing the model results with satellite images using a skill score based on the distance between simulated particles and the nearest observed rafts divided by the travel distance of the particles. The optimal windage coefficients ranged between 2 and 3 % and produced pathways comparable to the observations from satellites. The simulation results showed that the pumice rafts moved from Fukutoku-Okanoba toward the Ryukyu Islands for approximately two months prior to being pushed by the north-easterly wind toward Taiwan against the Kuroshio. The methods presented here may become a valuable tool in managing coastal hazards due to diverse marine debris.

Numerical studies on dynamic and oil-water separation characteristics in cyclonic flotation column

In order to improve the separation efficiency of oily wastewater, a new type of cyclonic flotation column is proposed, which combines low-intensity swirl with air flotation. A computational fluid dynamics (CFD) simulation is conducted to evaluate the performance of the cyclonic flotation column. the population balance model (PBM) is used to provide and describe the initial flow field, bubble distribution, and the Lagrangian particle tracking (LPT) model is used to predict the separation efficiency and movement of oil droplets with different diameters trajectory. Numerical simulation results show that the collision efficiency of bubbles and oil droplets can be promoted by the increase of the turbulent intensity, which can accelerate the oil-water separation process. For small diameter oil droplets (10 µm), the separation efficiency can also reach 92%. The CFD model is validated against the experimental results, which indicates that the numerical simulation method is stable and reliable.

Double-plume Lagrangian particle tracking model and its application in deep water oil spill

Double-plume Lagrangian particle tracking model and its application in deep water oil spill

P84: The impact of temporal synchronization on platelet activation in LVAD patients: CFD and PIV study for the HeartMate3 pulsatility mode.

Study: LVAD patients continue to experience high rates of stroke. Stasis and high shear stresses contribute to platelet activation in the left ventricle, that can lead to thrombus formation. A pulsatility mode was incorporated into the HeartMate3 to improve in-pump washout. The pump speed modulation occurs every two seconds, independently of the cardiac cycle even in patients with preserved native contractility. This study examines intraventricular washout under different LVAD pulsatility/native cardiac cycle synchronization. Methods: A patient-specific 3D time-resolved computational fluid dynamics (CFD) simulation captures the hemodynamics in the left ventricle implanted with an LVAD. Lagrangian particle tracking models platelet motion from the mitral valve, across the left ventricle and out through the outflow cannula. The residence time and shear stress history for each platelet is tracked to determine its risk of activation. Four different temporal synchronizations between the LVAD pulsatility and the native contractility are studied: contraction, peak contraction, relaxation, and peak relaxation. The flow rate through the cannula is prescribed from flow meter data in the experimental campaign. Particle image velocimetry (PIV) experiments measured the in-plane and through plane velocity fields at two orthogonal planes in the ventricle. This PIV data is compared to the CFD to benchmark the simulations. Results: The different pulsatility mode synchronizations result in significantly different time-dependent flow rates through the cannula. The difference between these flow rates results in different hemodynamics patterns in the ventricle. The velocity fields from the CFD models agree closely with the results from the PIV experiments, and take these in a new direction with the use of Lagrangian platelet tracking. Recirculation zones develop underneath the aortic valve and around the cannula/apex pocket, resulting in areas of stasis for the platelets. By identifying platelets that experience both high shear stress history and long residence time, the thrombogenicity of the different synchronizations is evaluated.