Particle Tracking Module Research Articles

A quick parameter configuration tool for SCHISM’s ocean transport simulation of radioactive materials

Abstract A quick tool capable of processing output files generated by the SCHISM particle tracking module has been developed to handle complex data processing procedures and conduct parameter sensitivity testing. This tool performs calculations, considering the influence of half-lives and partition coefficients, for the conversion of activity concentrations, plots particle diffusion trajectories, conducts statistical analyses of regional particle amounts, and presents activity concentration within the defined area. Using the IAEA MODARIA program as an example, this study investigates the transport of radioactive 137Cs in the ocean following the Fukushima accident on March 11, 2011. A three-year diffusion simulation was conducted by incorporating data such as ocean currents, wind fields, and tides. The calculated results demonstrate a high level of consistency with measurements, and the calculated results in the low activity concentration fall within the variability range reported in the literature.

Transportation and sealing pattern of the temporary plugging ball at the spiral perforation in the horizontal well section

Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However, the transportation and sealing law of temporary plugging balls (TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of perforations. Adjusting the fracturing fluid injection rate from low to high can control the position of the TPBs, improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.

Sensitivity analysis and calibration of a Lagrangian particle tracking using GPS-tagged drifters

A Lagrangian particle tracking module within a hydrodynamic model in Environmental Fluid Dynamic Code Plus (EFDC+) was used to track the movements of large floating marine carcasses. This research used data from six GPS-tagged drifters collected in April 2017 by NOAA to conduct a sensitivity analysis and calibration on the Lagrangian particle tracking module. These analyses investigate the influence of specific parameters, notably wind drag and number of vertical layers in the model. Changing these parameters resulted in observable changes in the trajectories of tracked particles. The results of the sensitivity experiments were compared using the Skill Score statistic. Adding wind drag to the LPT was a pivotal alteration, augmenting the model predictive capabilities by increasing the Skill Score value from 0.23 to 0.47. Further tests examined the impact of varying wind drag coefficients (A and B) which are the slope and y-intercept of a linear equation used to describe overall drag coefficient (CD) as a function of wind velocity. These coefficients are employed in EFDC + software and altering them revealed that coefficient A has a larger impact on the model predictions compared to coefficient B. Finally, the transition from a 2D to a 3D model had a more significant impact on the results compared to increasing the number of vertical layers in the 3D configuration. However, the findings indicated that changing the model from 2D to 3D may not yield a large enough improvement in accuracy that would justify the additional computational demands associated with a 3D model when running long periods of time (several years). The study results have valuable implications for developing accurate and precise models of hydrodynamic systems emphasizing the importance of wind in LPT models and the efficiency of 2D vs 3D models for LPT simulations in the Mississippi Sound area.

Evaluating hydrodynamics and implications to sediment transport for tidal restoration at Swan Cove Pool, Virginia

Coastal restoration projects are significantly important in coastal ecosystems as wetland losses accelerate. This study investigates tidal hydrodynamics and the potential impacts of a waterway opening on an existing roadway to restore and revitalise salt marshes in a small estuarine system in Virginia, USA. A depth-integrated, discontinuous Galerkin shallow-water equations model (DG-SWEM) is applied for astronomic tide simulation. The model employs a high-resolution unstructured mesh with a minimum element size of less than one meter and resolves complex tidal flows in the entire barrier island system, including the existing culvert gate and canal system. Compared to the existing system, the water exchange increased dramatically (flushing time also dramatically decreased) under the opened scenarios regardless of the opening width (22.9-, 30.5-, and 38.1-m width). By increasing the opening width, peak velocity through the proposed opening decreased 30–40%, and the maximum shear stress was reduced by more than half. The high-resolution model represented complex tidal flows, including eddies, and assisted in striking a balance of water-exchange capability, opening stability, and minimising their potential erosions for the opening design. Besides, erosion and sediment transport potentials for suspended sediments were estimated using bed shear stress and a Lagrangian particle tracking module. Such proxy modelling approach allows for the impact assessment of civil engineering and ecological waterworks in complex and highly damped tidal flow areas and is readily transferrable to other like systems (e.g. causeway construction, causeway cutting, biota passageways, and inlet modification).

Complementary Mass Transport Investigations in Open-Cell Foams: Full-Field Computational Fluid Dynamics Simulation with Random-Walk Microscopic Particle Tracking and Methane Nuclear Magnetic Resonance Displacement Measurements

Numerical simulation can provide detailed understanding of mass transport within complex structures. For this purpose, numerical tools are required that can resolve the complex morphology and consider the contribution of both convection and diffusion. Solving the Navier–Stokes equations alone, however, neglects self-diffusion. This influences the simulated displacement distribution of flow especially in porous media at low Péclet numbers (Pe < 16) and in near-wall regions where diffusion is the dominant mechanism. To address this problem, this study uses μCT-based computational fluid dynamics (CFD) simulations in OpenFOAM coupled with the random-walk particle tracking (PT) module disTrackFoam and cross-validated experimentally using pulsed-field gradient (PFG) nuclear magnetic resonance (NMR) measurements of gas flow within open-cell foams (OCFs). The results of the multi-scale simulations—with a resolution of 130–190 µm—and experimental PFG NMR data are compared in terms of diffusion propagators, which are microscopic displacement distributions of gas flows in OCFs during certain observation times. Four different flow rates with Péclet numbers in the range of 0.7–16 are studied in the laminar flow regime within 10 and 20 PPI OCFs, and axial dispersion coefficients were calculated. Cross-validation of PFG NMR measurements and CFD-PT simulations revealed a very good matching with integral differences below 0.04%, underpinning the capability of both complementary methods for multi-scale transport analysis.

Analysis of light field and flow field of vortex rods tube photobioreactor based on field synergy principle

A new static mixer called the vortex rod static mixer was introduced into the photobioreactor. This study focused on the vortex rod tubular reactor as the subject of investigation. The effects of different incident light field intensities (I0 = 375 μmol/(m2·s), 800 μmol/(m2·s), and 1200 μmol/(m2·s)) on reactor efficiency were simulated using the CFD simulation method, considering variations in vortex rod arrangement (60°, 90°, and 120°) and tilt angle (α = 27°, 36°, 45°, 54°, and 63°). In the SST turbulence simulation flow field results, the movement process of algae cells in the tube was simulated using the particle tracking module. By taking into account the average frequency of the light-dark cycle, the enhancement efficiency of the light-dark cycle, and the synergy angle of the light gradient and velocity field, the following results were obtained: the optimum tilt angle for the vortex rod is α = 45°. For incident light field intensities of I0 = 375 μmol/(m2·s) and 800 μmol/(m2·s), the 60° arrangement yielded the best results, resulting in a 54.491 % and 66.258 % increase in cycle frequency, an 18.747 % and 22.795 % enhancement in efficiency, and an average |cosβ| = 0.68055. For an incident light field intensity of I0 = 1200 μmol/(m2·s), the 90° arrangement proved to be the most effective, resulting in a 57.580 % increase in cycle frequency, an 18.058 % enhancement in efficiency, and an average |cosβ| = 0.68975.

Examining the effect of salinity on dolphin mortality using Lagrangian particle tracking in a hydrodynamic model

Numerous dolphins are found dead on beaches and waterways of the Gulf of Mexico and Mississippi Sound every year. In 2019 an unusual mortality event (UME) occurred when 337 deceased bottlenose dolphins were stranded between Louisiana, Mississippi, Alabama, and Florida. According to NOAA, based on observations of skin lesions or distinct ulcerative dermatitis and other internal pathologic findings and the environmental conditions during that period of time, the identified cause of this UME was determined to be protracted exposure to low salinity waters. Dolphin carcasses are often found stranded on beaches days after they die. Consequently, their initial place of death is unknown. In this study, an existing 2D hydrodynamic model (EFDC+ 11.2) of the Mississippi Sound simulated by Armandei et al. (2021) was used to track dolphin carcass movement and to simulate salinity at the time and location of each predicted dolphin's death. Particles within the Lagrangian particle tracking module were used to represent the movement of 19 dolphin carcasses. A large number of particles (virtual dolphin carcasses) were seeded throughout the model domain and tracked for five days. These results were used to hindcast each dolphin's original location of death. The results indicate that the most likely place of death for 12 dolphins stranded on the beaches of Mississippi, along with the two found on Ship and Horn Islands, was west of their stranding location., For both of the dolphins stranded on Dauphin Island, the most likely place of death was in the Mobile Bay area north of where they were found. The remaining three dolphins found dead on barrier islands, most likely originally died in close proximity to their stranding locations. The average simulated salinity of all the dolphins' most probable original place of death was below five except for two cases. These results are compared to the salinity of the Mississippi Sound during Bonnet Carré spillway opening and non-opening dates. The results highlight the significant impact of the spillway's opening on the reduction of salinity and its association with dolphin mortality.

Improvement of Electron Gun Breakdown Performance Through Surface Flashover and Discharge Studies

The reliable and uninterrupted operation of electron gun for refractory metal melting application requires a systematic study of surface flashover and electron beam-generated plasma discharge (EB-GPD) characteristics. These are highly influenced by insulator and target material characteristics. However, both lead to high-voltage (HV) breakdown of electron gun due to electric field intensification, insulator failure due to its sputtering and coating by backscattered electrons as well as secondary emitted electrons from the target material. This article deals with performance optimization of 2700-bent directly heated electron gun (DHEG) for device improvement. To achieve this, systematic study and analysis of insulator and target materials have been done through: 1) detailed 3-D simulations to study surface flashover by investigating electric field intensification in electron gun and 2) detailed study of discharge characteristics to investigate backscattered and secondary emitted electrons. The 3-D electrostatic, electromagnetic, and particle tracking simulations are done by using the Computer Simulation Technology (CST) Studio Particle tracking module. Discharge properties are evaluated by using disk-type Langmuir probe (LP) measurements accompanied by detailed mathematical calculations. This work helps to address the HV breakdown issue in electron gun, which is of great practical significance.

3-D analysis of electron beam shape at target plane through parametric variation of an indirectly heated cathode-based electron gun

In this paper, a detailed 3-D analysis of the electron beam shape at the target plane of high power (60 kW, 60 kV, 1 A) 2700-bent indirectly heated cathode-based electron gun has been successfully carried out. This work will help analyse individual electron beam trajectories in the actual 3-D plane to ensure optimum electron beam bending and focusing at the target plane. Moreover, due to the presence of an additional electrode in an indirectly heated cathode-based electron gun i.e., a filament which is resistively heated and an indirectly heated solid cathode (heated through electron bombardment), this analysis becomes even more imperative. The work carried out in this paper will ensure better performance, characterization, and optimization of the 2700-bent indirectly heated cathode-based electron gun. Rigorous simulation work has been carried out by performing 3-D electrostatic, electromagnetic, and particle tracking simulations using CST Studio Particle Tracking Module. Adaptive mesh refinement has been utilized to ensure high accuracy of the results obtained. An optimum filament-solid cathode interspacing was found, using strip-shaped filament by providing a higher negative potential to the grid cup. It led to a well-focused 2700-bent electron beam, exhibiting minimum electron beam emittance at the target plane.

Study on dust control technology of mobile spray combined with full-section fog curtain in return airway of header working face.

For the problem of coal dust pollution in the return air lane of the comprehensive mining working face of soft rock mines.Based on the principle of supersonic siphon pneumatic atomization dust control, mobile vehicle-mounted pneumatic spraying combined with full-section fog curtain dust control technology is proposed to address the coal dust pollution problem in the return air tunnel of the comprehensive mining working face of soft rock mines. This technology has a wider spraying range, stronger wind resistance and lower energy consumption.Using the k-ε turbulence module and the fluid flow particle tracking module of COMSOL simulation software, a three-dimensional numerical model of the return air tunnel was established. The effect of wind flow characteristics on the diffusion range of coal dust and fog droplets was analysed, and the dust transport pattern and dust control effect of the new technology were obtained for different cross-sectional return airways. The results show that the velocity of the wind flow is continuously decayed by the slope, and the dust of different particle sizes is distributed differently by the inertial force. Coal dust with particle sizes larger than 6.5 μm accumulates below the structure at a lower velocity, and coal dust with particle sizes smaller than 4.5 μm is mostly suspended above the structure at a higher velocity. The device effectively stops the transport of dust and covers the whole section of the roadway, and the dust removal efficiency reaches 96.53%~97.93%, which provides relevant theoretical support and treatment means for the control of dust pollution in the return airway of coal mines.

Modeling of an Impedimetric Biosensor with Ultrasonic-Assisted Cell Alignment for the Detection of Yeast

Yeast is an integral part of our environment. The detection of yeast is of great significance in many fields. The impedance-based sensor with interdigital microelectrodes is a promising method to establish a simple and portable detection system. However, the positions of yeast cells greatly influence the impedance variation and eventually the sensitivity of detection. In this study, an impedimetric biosensor with ultrasonic-assisted cell alignment for yeast detection was proposed. In order to verify the feasibility of this biosensor, finite element modeling was conducted using the software COMSOL. The acoustic pressure field and the acoustic radiation force exerted on yeast cells were investigated. Cell positions in the microfluidic channel were determined using the fluid particle tracking module. After that, the impedance between the microelectrodes was calculated. Yeast suspensions with different cell concentrations were used as the tested samples for the simulation. The proposed sensor showed a higher sensitivity than the conventional impedimetric biosensor on which the cells were randomly located. It can be used for the detection of microorganisms. This finite element modeling provided an effective approach for the design of biosensors.

Lagrangian Modeling of Marine Microplastics Fate and Transport: The State of the Science

Microplastics pollution has led to irreversible environmental consequences and has triggered global concerns. It has been shown that water resources and marine food consumers are adversely affected by microplastics due to their physico-chemical characteristics. This study attempts to comprehensively review the structure of four well-known Lagrangian particle-tracking models, i.e., Delft3D—Water Quality Particle tracking module (D-WAQ PART), Ichthyoplankton (Ichthyop), Track Marine Plastic Debris (TrackMPD), and Canadian Microplastic Simulation (CaMPSim-3D) in simulating the fate and transport of microplastics. Accordingly, the structure of each model is investigated with respect to addressing the involved physical transport processes (including advection, diffusion, windage, beaching, and washing-off) and transformation processes (particularly biofouling and degradation) that play key roles in microplastics’ behavior in the marine environment. In addition, the effects of the physical properties (mainly size, diameter, and shape) of microplastics on their fate and trajectories are reviewed. The models’ capabilities and shortcomings in the simulation of microplastics are also discussed. The present review sheds light on some aspects of microplastics’ behavior in water that were not properly addressed in particle-tracking models, such as homo- and hetero-aggregation, agglomeration, photodegradation, and chemical and biological degradation as well as additional advection due to wave-induced drift. This study can be regarded as a reliable steppingstone for the future modification of the reviewed models.

Simulation of Marine Leisure Accidents Using Random-Walk Particle Tracking on Macro-Tidal Environment

In the west coast of Korea (WCK), macro-tidal environments with wide tidal flats yield distinctive characteristics such as recursive tidal currents and tidal asymmetry. Here, we proposed an efficient search and rescue (SAR) computation method for WCK conditions (where bottom shapes affect nearshore sticking) using a finely resolved wet–dry circulation model. A random-walk particle tracking module (PTM) was applied to an unstructured finite element model to provide the SAR information needed to mitigate the consequences of marine leisure accidents. To capture the unique external forcing characteristics affecting the nearshore SAR case, sensitivity tests, which considered the characteristics of human bodies in particle representation, were performed on an idealized basin under typical external forcing. Furthermore, the effects of surface drag were included to represent real conditions more accurately. Our simulations showed that the accuracy of initial accident times for in situ mannequin floating tests (where several initial locations and times of accidents were used) directly affected the accuracy and effectiveness of SAR missions. However, to understand and predict the missing floating person in real time, additional intensive field experiments are required that account for the local geomorphological characteristics, external real-time temporal tides, and wind forcing incorporating extreme weather conditions.

A novel molecular communication inspired detection method for the evolution of atherosclerosis

Background and objective: Atherosclerosis is a leading cause of potentially serious cardiovascular diseases such as heart attack, stroke, and peripheral artery disease. Due to the prolonged and non-reversible process of thickening arteries walls, atherosclerosis plaques in the blood vessels are formed that restrict the blood flow. Early detection plays a vital role in minimizing the risk as there is no reliable method to detect the early stage of the disease. This paper proposes a novel atherosclerosis detection method based on the emerging paradigm of molecular communications. The work could pave the way to implement a low-cost and straightforward early detection method of atherosclerosis in the future.Methods: We used COMSOL to model the physical field, coupled the fluid module and the fluid particle tracking module, and mapped the contrast agent into nanoparticles (NPs). The NPs are released at the entrance of the blood vessel and received at the exit of the blood vessel, while NPs are propagating through different arterial stenosis. The arrival probability of NPs is defined as the ratio of the number of NPs that reach the outlet to the total number of released NPs. As a result of atherosclerosis, the arrival probability of Nps is affected by the dynamic flow nature changes, thereby reflecting the arterial stenosis degree. Furthermore, we introduce the multi-release method in this study, which has a similar concept of Inter-symbol interference in traditional communication. This multi-release method leads the overlapping concentrations of NPs remaining in the vessels and enhances the differences of arrival probability in different degrees of stenosis, which increases the chance of more observable results.Results: The assessment of arterial stenosis degree can be from the early stage to the late stage of the disease. To evaluate the arterial stenosis degree, we analyzed the Poincaré maps, representing the arrival probability of NPs at different arterial stenosis. Moreover, we could directly use data to quantify the pathological process at various stages. The difference between the data results obtained through multiple release methods is more prominent than a single-released method.Conclusions: This research proposes a new atherosclerosis detection method based on molecular communication, that is, to evaluate the arterial stenosis degree by modelling and using statistical data of NPs emission and reception in blood vessels. This method can not only use a simple method to detect the early stage of the disease. In addition, we can directly use data to quantify the pathological process of each stage, which is straightforward to assist doctors and may reduce the labour cost of traditional detection.

Model-based estimation of plastic debris accumulation in Banten Bay, Indonesia, using particle tracking - Flow model hydrodynamics approach

Coastal pollution caused by marine debris in Banten Bay is increasing and threatening the environmental and ecological sustainability of the bay's coastal area. This study aims to simulate the particle tracking of floating plastic debris within Banten Bay and to estimate the coastal debris accumulation for the period 2018 to 2028 based on numerical spatial modeling. To determine the dominant direction of plastic debris flow, we recorded floating plastic waste at four locations (Bojonegara port, Karangantu Estuary, Cibanten Estuary, and the Sunda Straits) by releasing wooden drifters. The numerical model was developed using a Particle Tracking module based on the Langevin equation. In comparison to data provided by the drifter survey, the particle tracking showed a similar distribution trace that tended to move westward during the northeast monsoon and eastward during the southwest monsoon. During the northeast monsoon, marine debris intake peaked, ranging from 2.25 kg to 5.75 kg. We estimated that over the ten years modeled plastic debris accumulation would increase by approximately 11%, to a maximum rate of 9.42 kg/day. Of particular concern, it is modeled that 41% of Banten Bay will be covered by plastic debris in 2028 if effective mitigations are not immediately applied. We recommend conducting a coastal cleanup operation every ten days so that coastal debris deposits can be well-controlled.

Performance optimization of indirectly heated cathode based electron gun by controlling high voltage surface flashover and beam positioning at target plane

In this paper, an improved design of a practical 2700-bent, 60 kV, 60 kW, indirectly heated cathode-based electron gun has been proposed in order to reduce high voltage breakdown in the electron gun. This ensures reliable and uninterrupted operation of the electron gun for melting and evaporation applications. For this purpose, 1) shield electrodes have been optimally designed for gun insulators in order to provide desired voltage grading/shielding and 2) optimization of positioning of the gun electrodes and optimal current in Helmholtz coil in order to ensure desired 2700-bent electron beam at the target plane, have been achieved. A new optimization technique incorporating formulation of a 3-D cost function is developed and is implemented by using an open-source web application utilizing python script. Electrostatic and electromagnetic 3-D gun simulations are carried out by using CST Studio Particle Tracking Module with modified parameters. Trial experiments have been conducted to monitor breakdown signal which showed improvement in surface flashover performance of electron gun. Molybdenum tablets were successfully melted at target plane by achieving the desired 2700-bent electron beam. Dimensions of molybdenum melt pool and simulation results showed good correspondence.

Study and Analysis on the Influence Degree of Particle Settlement Factors in Pipe Transportation of Backfill Slurry

In this study, we developed a pipeline transport model to investigate the influence of particle sedimentation factors on slurry transportation through pipelines. The particle tracking module of the software was used to simulate the transport process, and the influences on the sedimentation rate were analyzed considering the slurry concentration, particle size, and flow velocity. The established model exhibited small calculation errors. In addition, the results revealed that the proposed model is reliable for calculating the degree of influence of various factors on particle sedimentation. The effect of the particle sedimentation rate on the pipeline slurry was explored considering the particle size, slurry concentration, and flow velocity. The sedimentation rate was positively related to particle size and adversely related to the slurry concentration and flow velocity. Indeed, study on the sedimentation rate requires considering a reasonable range of particle sizes, preparing a slurry with an appropriate concentration, and adjusting an appropriate flow velocity. Numerical simulations were performed using the filling data as the background for a sample mining area. The experimental results showed optimal slurry concentration and particle size of 60% and 25.25 µm, respectively.

Identification of Marine Debris Sources in Kuta Beach, Bali, Indonesia

Maharta, I.P.R.F.; Radjawane, I.M.; Suprijo, T.; Park, H., and Hendrawan, I.G., 2021. Identification of marine debris sources in Kuta Beach, Bali, Indonesia. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 594–598. Coconut Creek (Florida), ISSN 0749-0208. Kuta Beach is one of the beaches with the biggest tourist arrivals in Bali. In recent years Kuta beach has received shipments of marine debris from the Bali Strait. Kuta Beach area gets an average of piles of marine debris reaching ± 30 tons/day and the peak occurred in January 2014 which reached ± 1,700 tons. Previous studies only carried out simulations with sources of marine debris from outside the Bali Strait and the coast in Bali. This study aims to determine the marine debris that reaches Kuta Beach with the source of debris from rivers in the west season (January 2019). The Finite Volume Coastal Ocean Model (FVCOM) is used to obtain the circulation of current patterns and patterns of movement of particles by using the Lagrangian Particle Tracking module, with the sources of the debris from 8 river in Bali Strait. In general, the pattern of movement of currents in the Bali Strait at west season is dominantly moving towards the east due to the influence of the west monsoon winds. The simulation results show that particles that reach Kuta Beach are dominated by rivers that flow near Kuta Beach, with the river that gives the most debris is the Tukad Penet, which is 68.89% of the total marine debris that reaches Kuta Beach.

EXCHANGE CHARACTERISTICS OF AN ANTHROPOGENICALLY MODIFIED LAGOON: AN EULERIAN-LAGRANGIAN MODELING CASE STUDY WITH AN EMPHASIS ON THE NUMBER OF PARTICLES

The transport pathways and exchange characteristics of the Kamil Abdüş Lagoon in Istanbul, Turkey, are simulated using a finite element model with a Lagrangian particle tracking module. The lagoon is in the process of being reconfigured. The simulations are performed using a draft configuration. The effect of winds and the number of particles on the e-folding time is simulated. Results show that the lagoon is strongly dominated by winds with a correlation coefficient of 0.897 between the wind and residual current magnitudes. The lagoon e-folds in 9.1 days under realistic winds and in 14.3 days when there is no wind with confidence levels of 5%. The Lagrangian study uses six simulations with particle numbers ranging between 65073 and 2730486. A methodology based on confidence levels is proposed. It is observed that approximately 784 000 particles are necessary to obtain 5% level of confidence. With a problematic history and new planning options, the lagoon has a potential to be used as an example setting, all-field study ground for anthropogenically engineered coastal ecosystems.

Adapting HYDRUS-1D to simulate the transport of soil water isotopes with evaporation fractionation

Ecohydrological processes are often evaluated by studying the fate of stable water isotopes. However, isotopic fractionation during evaporation is often ignored or simplified in current models, resulting in simulation errors that may be propagated into practical applications of stable isotope tracing. In this study, we adapted and tested the HYDRUS-1D model, a numerical model widely used to simulate variably-saturated water flow and solute transport in porous media, by including an option to simulate isotope fate and transport while accounting for evaporation fractionation. The numerical results obtained by the adapted model were in excellent agreement with existing analytical solutions. Additional plausibility tests and field evaluation further demonstrated the adapted model's accuracy. A simple particle tracking algorithm was also implemented to calculate soil water's transit times and further validate the modified model's results. Transit times calculated by the particle tracking module (PTM) were similar to those estimated by the isotope peak displacement method, validating the applicability of the PTM. The developed model represents a comprehensive tool to numerically investigate many important research problems involving isotope transport processes in the critical zone.