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The Humboldt Archipelago (HAp), located off north-central Chile (~28° - 33° S) is one of the most productive marine zones of the Humboldt Current System (HCS). This area lies within a permanent upwelling zone, characterized by two upwelling centers, 100 km apart, that define the Coquimbo Bays System (CBS). The resulting increase in primary productivity and larval retention are mentioned as the main factors that explain the high biodiversity. However, how these upwelling centers interact remains unclear due to the interplay of various physical features such as the general circulation, the meso- and submeso-scale structures (e.g., eddies), and remote and local forcings (e.g., winds, topography) that affect larval transport in the HAp. In this study, we focus on the role played by geostrophic and Ekman currents in controlling the retention (and dispersion) of particles in these centers based on the analyses of satellite data and hydrodynamic model outputs. Lagrangian models are in particular carried out to document particles' transport during selected oceanic conditions corresponding to whether Ekman transport or geostrophic recirculation prevails or are debilitated. The latitudinal variation of the Ekman transport reveals two maxima at each upwelling center with differences in spatial extent but not in intensity. Mean zonal geostrophic current occurs in alternating flow at each upwelling center. Results of the Lagrangian experiments highlight the importance of the cross-shore geostrophic flow on larval transport, where an increased transport of particles to the north and northwest occurs at the southern upwelling center, while the northern upwelling center (where HAp is located) received particles from the south and retained particles released in the same area, which is related to the cyclonic geostrophic recirculation and lower Ekman transport. Particle retention increased with depth and under the relaxation and downwelling scenarios revealing the importance of wind alternation for larval retention. The CBS could act as an upwelling shadow in the south and an upwelling trap in the north where the onshore flow of geostrophic current could enhance larval retention and recruitment over longer periods when compared with the Ekman transport timescale. [ABSTRACT FROM AUTHOR]

Timely forecast of atmospheric pollutants fallout due to accidental fires can provide decision-makers with useful information for effective emergency response, for planning environmental monitoring and for conveying essential alerts to the population to minimize health risks. The SAPERI project (Accelerated simulation of accidental releases in the atmosphere on heterogeneous platforms—from its Italian initials) implements a modeling chain to quickly supply evidence about the dispersion of pollutants accidentally released in the atmosphere, even in the early stages of the emergency when full knowledge of the incident details is missing. The SAPERI modeling chain relies on SPRAY-WEB, a Lagrangian particle dispersion model openly shared for research purposes, parallelized on a GPU to take advantage of local or cloud computing resources and interfaced with open meteorological forecasts made available by the Meteo Italian SupercompuTing PoRtAL (MISTRAL) consortium over Italy. The operational model provides a quantitative and qualitative estimate of the impact of the emergency event by means of a maximum ground level concentration and a footprint map. In this work, the SAPERI modeling chain is tested in a real case event that occurred in Beinasco (Torino, Italy) in December 2021, mimicking its use with limited or missing local input data as occurs when an alert message is first issued. An evaluation of the meteorology forecast is carried out by comparing the wind and temperature fields obtained from MISTRAL with observations from weather stations. The concentrations obtained from the dispersion model are then compared with the observations at three air quality monitoring stations impacted by the event. [ABSTRACT FROM AUTHOR]

Regardless of the specific technology adopted, the use of desalination to produce fresh water from seawater results in a discharge of brine effluent containing a high concentration of salts and other desalination by-products that must be dealt with appropriately. Until now, this effluent has most commonly been discharged into the sea through a submarine outfall. Computational tools are used to simulate the behavior of these brine discharges to minimize their impact on the marine environment. Environmental assessments of desalination plants that are made using these tools can include consideration of the rates of effluent production and flow, diffuser configurations, marine conditions (e.g., currents, tides, salinity, temperature), and the proximity of plants to environmentally significant areas. Computational tools can also assist in the design of programs for monitoring the surroundings of brine disposal points. In this study, we developed a new tool for modeling brine discharges from submarine outfalls based on an adaptation of a near-field mathematical model coupled with a Lagrangian model. This new model was specifically designed for application to negatively buoyant effluent discharges. The near-field dilution results that were obtained for various current velocities and different diffuser vertical inclinations using this tool were compared with those obtained using a reference tool (Visual Plumes), considering four different desalination plants. Excellent correlation and a mean absolute percentage error lower than 10% were obtained between the two sets of results along with good reproducibility. Additionally, the existence of an integrated wave propagation model in the simulation software allowed the analysis of changes in the brine plume direction produced by waves formed far from the outfall area. Using the new model, it was possible to evaluate how the diffuser configuration affected the performance of the diffuser line, and the saline plume generated by the combined Lagrangian and near-field model realistically reproduced the behavior of a submarine brine outfall. This combined model is potentially applicable to a range of other situations, including studies that aim to minimize the environmental impact of desalination plants based on considerations of outfall locations and optimization of the diffuser configuration. [ABSTRACT FROM AUTHOR]

The Humboldt Archipelago (HAp), located off north-central Chile (~28° - 33° S) is one of the most productive marine zones of the Humboldt Current System (HCS). This area lies within a permanent upwelling zone, characterized by two upwelling centers, 100 km apart, that define the Coquimbo Bays System (CBS). The resulting increase in primary productivity and larval retention are mentioned as the main factors that explain the high biodiversity. However, how these upwelling centers interact remains unclear due to the interplay of various physical features such as the general circulation, the meso- and submeso-scale structures (e.g., eddies), and remote and local forcings (e.g., winds, topography) that affect larval transport in the HAp. In this study, we focus on the role played by geostrophic and Ekman currents in controlling the retention (and dispersion) of particles in these centers based on the analyses of satellite data and hydrodynamic model outputs. Lagrangian models are in particular carried out to document particles’ transport during selected oceanic conditions corresponding to whether Ekman transport or geostrophic recirculation prevails or are debilitated. The latitudinal variation of the Ekman transport reveals two maxima at each upwelling center with differences in spatial extent but not in intensity. Mean zonal geostrophic current occurs in alternating flow at each upwelling center. Results of the Lagrangian experiments highlight the importance of the cross-shore geostrophic flow on larval transport, where an increased transport of particles to the north and northwest occurs at the southern upwelling center, while the northern upwelling center (where HAp is located) received particles from the south and retained particles released in the same area, which is related to the cyclonic geostrophic recirculation and lower Ekman transport. Particle retention increased with depth and under the relaxation and downwelling scenarios revealing the importance of wind alternation for larval retention. The CBS could act as an upwelling shadow in the south and an upwelling trap in the north where the onshore flow of geostrophic current could enhance larval retention and recruitment over longer periods when compared with the Ekman transport timescale.

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The current research aims to investigate the deposition and dispersion of nanoparticles for thermally developing laminar flow inside a cooling channel of a photovoltaic (PV) panel. The particle transport is modeled in an Eulerian-Lagrangian framework using a two-way coupling approach to perform the particle trajectories. In the absence of turbulent fluctuations, Brownian diffusion is the main force that contributes to particle deposition due to the small size of the particles used in the current study (below 100 nm). Several parameters were investigated such as inlet temperature, Reynolds number, nanoparticle size, and concentration in order to record the subsequent effects on the deposition efficiency, heat transfer coefficient, and pressure drop. There is no direct particle deposition model available in commercial computational packages such as fluent, so a deposition model was developed and programed in c-language using the user-defined function (UDF) capabilities available in the fluent solver to model how the particles are affected by wall impacts. Model validation was performed against the experimental studies found in the literature and showed good agreement. The efficiency of particle deposition on the channel wall was found to increase with decreasing nanoparticle size and/or Reynolds number. Furthermore, the deposition efficiency increased with the increase in fluid inlet temperature and nanofluid concentration. Moreover, the heat transfer rate was decreased as a result of decreasing nanofluid concentration caused by nanoparticle deposition on the channel walls, while the pumping power was also decreased due to concentration loss. [ABSTRACT FROM AUTHOR]

The feeding activities of fish in marine aquaculture have raised concerns about severe benthic pollution within the cage area. This paper suggests removing particulate waste from the cage area through the implementation of artificial upwelling (AU), a method likely to alleviate the organic burden within the cultivation area. A numerical model was developed to simulate AU-induced particulate matter transport under different operating conditions, with the majority of simulation results validated through flume experiments. The influence of particle characteristics, environmental conditions, and engineering parameters of AU on organic matter transport are discussed. In particular, our study offers a detailed analysis of the minimum initial upwelling velocity required to transport particulate waste to a designated distance. It also recommends situating the bottom of the cage above the maximum height of the waste plume to effectively segregate fish from the waste carried by the upwelling. [ABSTRACT FROM AUTHOR]

Regardless of the specific technology adopted, the use of desalination to produce fresh water from seawater results in a discharge of brine effluent containing a high concentration of salts and other desalination by-products that must be dealt with appropriately. Until now, this effluent has most commonly been discharged into the sea through a submarine outfall. Computational tools are used to simulate the behavior of these brine discharges to minimize their impact on the marine environment. Environmental assessments of desalination plants that are made using these tools can include consideration of the rates of effluent production and flow, diffuser configurations, marine conditions (e.g., currents, tides, salinity, temperature), and the proximity of plants to environmentally significant areas. Computational tools can also assist in the design of programs for monitoring the surroundings of brine disposal points. In this study, we developed a new tool for modeling brine discharges from submarine outfalls based on an adaptation of a near-field mathematical model coupled with a Lagrangian model. This new model was specifically designed for application to negatively buoyant effluent discharges. The near-field dilution results that were obtained for various current velocities and different diffuser vertical inclinations using this tool were compared with those obtained using a reference tool (Visual Plumes), considering four different desalination plants. Excellent correlation and a mean absolute percentage error lower than 10% were obtained between the two sets of results along with good reproducibility. Additionally, the existence of an integrated wave propagation model in the simulation software allowed the analysis of changes in the brine plume direction produced by waves formed far from the outfall area. Using the new model, it was possible to evaluate how the diffuser configuration affected the performance of the diffuser line, and the saline plume generated by the combined Lagrangian and near-field model realistically reproduced the behavior of a submarine brine outfall. This combined model is potentially applicable to a range of other situations, including studies that aim to minimize the environmental impact of desalination plants based on considerations of outfall locations and optimization of the diffuser configuration.

In 2017-2019 southeast Australia experienced one of its most severe droughts since 1900. Rainfall over the region encompassing the Murray-Darling Basin was consistently below average for three consecutive cool seasons, an unprecedented event on record. A strong positive Indian Ocean Dipole event has been previously suggested to have intensified the conditions of the drought in 2019, however the state of the climate drivers cannot fully explain the onset and development of this drought. In this study, we adopt a different approach to investigate processes other than remote climate drivers that may have triggered the drought. Using a Lagrangian model to identify moisture sources to the Murray Darling Basin, we show that local processes were crucial in explaining the onset and development of the drought. We identify the oceanic and terrestrial sources of atmospheric moisture over the Murray Darling Basin and show for the first time a significant decline in rainfall moisture supply from the Tasman Sea in 2017 and 2018. We further show that anomalous atmospheric circulation transported the expected moisture northward toward the Maritime Continent. Our results provide an explanation for the moisture and rainfall deficit that caused the 2017-19 southeast Australian drought. Understanding the processes that led to the 2017-2019 drought is an important step towards improved predictions and planning for future multi-year droughts in Australia.

Timely forecast of atmospheric pollutants fallout due to accidental fires can provide decision-makers with useful information for effective emergency response, for planning environmental monitoring and for conveying essential alerts to the population to minimize health risks. The SAPERI project (Accelerated simulation of accidental releases in the atmosphere on heterogeneous platforms—from its Italian initials) implements a modeling chain to quickly supply evidence about the dispersion of pollutants accidentally released in the atmosphere, even in the early stages of the emergency when full knowledge of the incident details is missing. The SAPERI modeling chain relies on SPRAY-WEB, a Lagrangian particle dispersion model openly shared for research purposes, parallelized on a GPU to take advantage of local or cloud computing resources and interfaced with open meteorological forecasts made available by the Meteo Italian SupercompuTing PoRtAL (MISTRAL) consortium over Italy. The operational model provides a quantitative and qualitative estimate of the impact of the emergency event by means of a maximum ground level concentration and a footprint map. In this work, the SAPERI modeling chain is tested in a real case event that occurred in Beinasco (Torino, Italy) in December 2021, mimicking its use with limited or missing local input data as occurs when an alert message is first issued. An evaluation of the meteorology forecast is carried out by comparing the wind and temperature fields obtained from MISTRAL with observations from weather stations. The concentrations obtained from the dispersion model are then compared with the observations at three air quality monitoring stations impacted by the event.

We propose a nonlinear lagrangian model that takes into account the dynamic interactions between the soil and a n-storey plane frame, which may be subjected to a seismic excitation through the soil. First, the interaction of the soil with the structure is modeled through a combination of springs and dampers representing the characteristics of the soil. In this model, the masses and stiffnesses of the structure elements are condensed to facilitate the analysis. Second, the Euler-Lagrange equations of the system are formulated and generalized for n floors. Third, these equations are discretized using the finite difference method to solve them using the Newton-Raphson method at each time step, during and after the seismic excitation, thus, determining the positions of each concentrated mass of the system. In addition, a linearization of the governing equations is performed in order to compare these results with those of the nonlinear model. Finally, the nonlinear model is used for the analysis of a 10-storey building, which has already been designed for linear geometric and material behaviors. For this analysis, the corrected acceleration record of the 2016 Pedernales (Ecuador) earthquake is used.

Cobia (Rachycentron canadum) is a coastal pelagic migratory fish species of tropical and subtropical waters, where it is an important game fish and it has been commercially expanded in offshore aquaculture systems. Understanding population connectivity is of utmost importance to the sustainable use and conservation of aquatic resources, and information on genetic diversity and structure is key element in unraveling differentiation when no clear physical barriers exist. In the present study, cobia genetic diversity and structure were depicted using mitochondrial DNA cytochrome b sequencing and microsatellite genotyping in samples from the Southwestern Atlantic and showed that a major single population inhabits the southern hemisphere. Cytochrome b sequencing also suggested that the Indian Ocean is the center of origin for this species' diversification. A hierarchical analysis of AMOVA compared sampling locations from the Northwestern Atlantic (from a previous study) with the Southwestern ones using nine shared microsatellite markers. Differentiation among groups (FCT = 0.41), Bayesian clustering analysis, and complementary ordination analyses (by discriminant analysis of principal components [DAPC] and factorial correspondence analysis [3D‐FCA]) presented a clear separation between the two hemispheres, supported by a Lagrangian model that explained the ocean dynamics over larval retention on the Western Atlantic. Another genetic subgroup intermingled with the main Southwestern group may also exist further south, probably associated with the Vitória‐Trindade Ridge and the local current systems. The distribution of this species in metapopulations is of extreme relevance for fisheries and fish hatcheries management in the Atlantic Ocean. [ABSTRACT FROM AUTHOR]

This study classifies the spatial distribution of heavy precipitation in summer (June–August) from 1979 to 2021 in the three provinces of Northeast China (TPNC) into two patterns by using the self‐organizing maps (SOM) neural network, and then quantitatively analyzes their moisture transport channels and sources using the Lagrangian model. The results show that the summer heavy precipitation in TPNC can be divided into the northern and southern patterns according to the distribution of the heavy precipitation. Both patterns of heavy precipitation are affected by the low‐level vortex west of TPNC, but the strength and shape of the low vortex are different. The northern pattern is mainly influenced by the westerly flow in the vortex in the mid‐high latitudes, which transports moisture from the upstream westerly region into TPNC. The southern pattern is mainly affected by the southerly jet stream southeast of TPNC, which conveys a large amount of moisture from the East Asian summer monsoon region into TPNC. In terms of the summer climatological mean, the northern pattern has a higher precipitation recycling rate, while the southern pattern has a lower recycling rate. [ABSTRACT FROM AUTHOR]

Dropwise condensation (DWC) of steam over hybrid hydrophobic–hydrophilic surfaces is numerically investigated via a phenomenological, Lagrangian model. The full non-dimensionalization of the heat transfer model, needed to determine the droplet growth, allows for generalization of computational results. Hybrid surfaces characterized by recursive geometries are implemented via the introduction of proper boundary conditions. The numerical size distribution of both the large and the small droplet populations, crucial for development of simplified, statistically sound models, is compared with empirical and theoretical correlations. Then, the validation with experimental data involving DWC over an hybrid surface is successfully conducted and the heat flux is enhanced under different operating conditions via hybrid geometry optimization. [ABSTRACT FROM AUTHOR]

The transport and prediction of the concentration of particles in confined spaces are crucial for human well-being; this has become particularly evident during the current worldwide pandemic. Computational fluid dynamics (CFD) has been widely used for such predictions, relying on Eulerian–Eulerian (EE) and Eulerian–Lagrangian (EL) models to study particle flow. However, there is a lack of research on industrial factories. In this study, a scaled laboratory in an industrial factory was established for oil mist particles in a machining factory, and oil mist dispersion experiments were conducted under roof exhaust and mixed ventilation conditions. After that, the oil mist concentration distribution in the factory under the same working conditions was calculated by Eulerian and Lagrangian methods, and the corresponding calculation errors and resource consumption were compared. It was found that the simulation results of both methods are acceptable for mixed ventilation and roof exhaust ventilation systems. When there are more vortices in the factory, the Lagrangian method increases the computation time by more than 53% to satisfy the computational accuracy, and the computational error between the Eulerian and Lagrangian methods becomes about 10% larger. For oil mist particles with an aerodynamic diameter of 0.5 μm, both Eulerian and Lagrangian methods have reliable accuracy. Based on the same flow field, the Lagrangian method consumes more than 400 times more computational resources than the Eulerian method. This study can provide a reference for the simulation of indoor particulate transport in industrial factories. [ABSTRACT FROM AUTHOR]

Abstract This study classifies the spatial distribution of heavy precipitation in summer (June–August) from 1979 to 2021 in the three provinces of Northeast China (TPNC) into two patterns by using the self‐organizing maps (SOM) neural network, and then quantitatively analyzes their moisture transport channels and sources using the Lagrangian model. The results show that the summer heavy precipitation in TPNC can be divided into the northern and southern patterns according to the distribution of the heavy precipitation. Both patterns of heavy precipitation are affected by the low‐level vortex west of TPNC, but the strength and shape of the low vortex are different. The northern pattern is mainly influenced by the westerly flow in the vortex in the mid‐high latitudes, which transports moisture from the upstream westerly region into TPNC. The southern pattern is mainly affected by the southerly jet stream southeast of TPNC, which conveys a large amount of moisture from the East Asian summer monsoon region into TPNC. In terms of the summer climatological mean, the northern pattern has a higher precipitation recycling rate, while the southern pattern has a lower recycling rate.

A Lagrangian model which simulates the transport of radionuclides released from nuclear accidents in the western Mediterranean Sea was recently described. This model was developed in spherical coordinates and includes three-dimensional mixing due to turbulence, advection by currents, radioactive decay, and radionuclide exchanges between water and bed sediments. Water circulation was downloaded from the HYCOM global ocean model. Water–sediment interactions were described using a dynamic model based on kinetic transfer coefficients. Mixing, decay, and water–sediment interactions were solved using a stochastic method. Now, a dynamic biological uptake model consisting of four species (phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish) has been integrated within the transport model to be able to assess the effects of a potential accident in biota and fishery regions. The model has been set up for 137 Cs and 90 Sr due to the radiological relevance of these radionuclides. Several hypothetical accidents were simulated, resulting in 137 Cs concentrations in biota significantly higher than background levels. In contrast, 90 Sr accumulates in the food chain to a considerably weaker extent. [ABSTRACT FROM AUTHOR]

We propose a nonlinear lagrangian model that takes into account the dynamic interactions between the soil and a n-storey plane frame, which may be subjected to a seismic excitation through the soil. First, the interaction of the soil with the structure is modeled through a combination of springs and dampers representing the characteristics of the soil. In this model, the masses and stiffnesses of the structure elements are condensed to facilitate the analysis. Second, the Euler-Lagrange equations of the system are formulated and generalized for n floors. Third, these equations are discretized using the finite difference method to solve them using the Newton-Raphson method at each time step, during and after the seismic excitation, thus, determining the positions of each concentrated mass of the system. In addition, a linearization of the governing equations is performed in order to compare these results with those of the nonlinear model. Finally, the nonlinear model is used for the analysis of a 10-storey building, which has already been designed for linear geometric and material behaviors. For this analysis, the corrected acceleration record of the 2016 Pedernales (Ecuador) earthquake is used. [ABSTRACT FROM AUTHOR]

The English-Chinese machine translation system is a current research topic. This paper designs an English-Chinese comparison system based on Lagrangian search mathematical algorithm. This paper proposes a Lagrangian algorithm to describe the English short syntax and improves the English-Chinese translation algorithm. When expanding nodes, the algorithm expands on the inspiration node and expands on other nodes. The experimental results show that the improved Lagrangian search algorithm can obtain better translation results and search efficiency in the system.

A highly extreme rainfall event occurred during June 15–17, 2021 (21·6 event) over southern Xinjiang (SXJ) of China, with daily rainfall overwhelming the climatological annual total at three national stations along the north of Kunlun Mountains. During this event, the SXJ is situated upstream of the 500 hPa trough line and close to the 200 hPa upper jet stream entrance, favouring the upper (lower) level divergence (convergence) with intensified ascending motions and prominent moisture convergence. We examined the moisture paths and sources for this significant rainfall event using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLT) model. The findings indicate that the majority of the moisture sources are located in areas west of the SXJ, extending from central Asia to the North Atlantic, whereas only a small number of trajectories originate from areas south or east of the SXJ. Seven relevant moisture sources for the rainfall event have been divided. About 80.0% of the total moisture is contributed by central Asia, which ranks top in terms of moisture contribution (∼33.2%), north Eurasia (∼25.7%), and water areas (∼17.7%), including the Mediterranean, Black and Caspian Sea region, while fractional moisture contributions among the other four regions are all below 8.0%. When compared to other parts of China (such as South China and East China), where southerly and/or easterly trajectories are the predominant moisture channels, the distribution patterns of moisture trajectories during this event are noticeably different.

The feeding activities of fish in marine aquaculture have raised concerns about severe benthic pollution within the cage area. This paper suggests removing particulate waste from the cage area through the implementation of artificial upwelling (AU), a method likely to alleviate the organic burden within the cultivation area. A numerical model was developed to simulate AU-induced particulate matter transport under different operating conditions, with the majority of simulation results validated through flume experiments. The influence of particle characteristics, environmental conditions, and engineering parameters of AU on organic matter transport are discussed. In particular, our study offers a detailed analysis of the minimum initial upwelling velocity required to transport particulate waste to a designated distance. It also recommends situating the bottom of the cage above the maximum height of the waste plume to effectively segregate fish from the waste carried by the upwelling.

The turbulent standard deviations and the turbulent third-order and fourth-order moments are the key turbulence dispersion parameters in Lagrangian dispersion models. However, the characteristics of these parameters under heavy haze conditions in urban areas have not been fully investigated, and the commonly used similarity relations of these parameters in models were based on observations in highly flat and sparsely populated areas. In this paper, the vertical profiles of these parameters and their local similarity relations under heavy haze conditions in the wintertime of Beijing have been analyzed by using data collected at a 325-m meteorological tower. The heavy haze process has been divided into three stages: transport stage (TS), cumulative stage (CS), and dispersion stage (DS). Results show that the turbulent dispersion parameters behave differently during three stages. In the TS and DS, the maxima appear in the profiles of the turbulent standard deviations above the urban canopy; in the CS, the turbulent standard deviation are almost constant with height. The analysis of the third and fourth order moments shows that the wind velocities above the urban canopy in the TS deviate from the Gaussian distribution more significantly than those in the CS and DS. The local similarity relations of the turbulent dispersion parameters in the TS, especially for the longitudinal wind components, are normally different from those in the CS and DS. Thus, different from the common assumptions in Lagrangian models, the turbulence dispersion in horizontal directions is anisotropic and should be parameterized by multiple similarity relations under heavy haze conditions. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we compare two different parameterisations for the wind velocity–component standard deviations. The first one is the (Hanna 1982) parameterisation, while the second is the (Scire et al. 2000) parameterisation, which provide the proper values and vertical structure for the wind standard deviations in the convective, neutral and stable layers, needed as input the Lagrangian stochastic model SPRAYWEB. The results of the model simulations carried out using the two parameterisations are compared, in terms of both mean concentration and concentration standard deviation, by evaluating some statistical indexes and trough scatter- and qq-plots. [ABSTRACT FROM AUTHOR]

This study serves as a basic study of the indoor dispersion of pollen particles, simulating the flow field and discussing the behavior of particles of different diameters in different rooms. By comparing the vertical velocity components of particles (w¯p$$ {\overline{w}}_{\mathrm{p}} $$) and the mean flow velocity of z‐direction component (wf$$ {w}_{\mathrm{f}} $$) plus the terminal settling velocity in a gravitational field (Vg$$ {V}_{\mathrm{g}} $$), the differences between w¯p$$ {\overline{w}}_{\mathrm{p}} $$ values and wf$$ {w}_{\mathrm{f}} $$ plus Vg$$ {V}_{\mathrm{g}} $$ values are found to occur mainly at locations close to the opposite wall of the inlet. The location of the differences between w¯p$$ {\overline{w}}_{\mathrm{p}} $$ values and wf$$ {w}_{\mathrm{f}} $$ plus Vg$$ {V}_{\mathrm{g}} $$ values is important findings of this study, which facilitates the improvement of the simulation method at a later stage and the rational design of indoor ventilation patterns to easily remove particles from the room. [ABSTRACT FROM AUTHOR]

The transport of radionuclides in the western Mediterranean Sea resulting from hypothetical accidents in a coastal nuclear power plant, and in a vessel with nuclear power or transporting radioactive material, was assessed with a Lagrangian model developed for this kind of accident assessment. Water circulation was obtained from the HYCOM global ocean model. The transport model was developed in spherical coordinates and includes advection by currents, three-dimensional turbulent mixing, radioactive decay, and radionuclide interactions between water and seabed sediments. Age calculations are included as well. A dynamic model based on kinetic transfer coefficients was used to describe these interactions. Mixing, decay, and water/sediment interactions were solved applying a stochastic method. Hypothetical accidents occurring at different moments were simulated to investigate seasonal effects in the fate of radionuclides. In addition, simulations for different radionuclides were carried out to investigate the effects of their different geochemical behaviours. Thus, in the case of a coastal release, 137 Cs is transported at long distances from the source, while 239 , 240 Pu stays close to the release point due to its strong reactivity, most of it being quickly fixed to the seabed sediment. In deep waters, in case of a surface release, 239 , 240 Pu spreads over larger areas since sediments are not reached by radionuclides. [ABSTRACT FROM AUTHOR]

Dropwise condensation (DWC) of steam over hybrid hydrophobic–hydrophilic surfaces is numerically investigated via a phenomenological, Lagrangian model. The full non-dimensionalization of the heat transfer model, needed to determine the droplet growth, allows for generalization of computational results. Hybrid surfaces characterized by recursive geometries are implemented via the introduction of proper boundary conditions. The numerical size distribution of both the large and the small droplet populations, crucial for development of simplified, statistically sound models, is compared with empirical and theoretical correlations. Then, the validation with experimental data involving DWC over an hybrid surface is successfully conducted and the heat flux is enhanced under different operating conditions via hybrid geometry optimization.

Abstract This study serves as a basic study of the indoor dispersion of pollen particles, simulating the flow field and discussing the behavior of particles of different diameters in different rooms. By comparing the vertical velocity components of particles (w¯p) and the mean flow velocity of z‐direction component (wf) plus the terminal settling velocity in a gravitational field (Vg), the differences between w¯p values and wf plus Vg values are found to occur mainly at locations close to the opposite wall of the inlet. The location of the differences between w¯p values and wf plus Vg values is important findings of this study, which facilitates the improvement of the simulation method at a later stage and the rational design of indoor ventilation patterns to easily remove particles from the room.

A rapid-response Lagrangian model for the use in simulation of the transport of a chemical pollutant in the Arabian/Persian Gulf is described. The model is well suited to the provision of a fast response after an emergency due to an accident or a deliberate spill. It is easy to set up for any situation since only requires the modification of a few input files specifying the pollutant properties and release characteristics. Running times are short, even on a desktop PC, which makes it appropriate for a rapid assessment of a hypothetical accident occurring in the region. Baroclinic circulation was obtained from an HYCOM ocean model, and tides were calculated using a barotropic model. The interactions of pollutants with sediments (uptake/release processes) were described using a dynamic approach based on kinetic transfer coefficients and a stochastic numerical method. Some examples of model applications are shown, showing the influence of the geochemical behaviour of the pollutant in its distribution patterns.

The transport and prediction of the concentration of particles in confined spaces are crucial for human well-being; this has become particularly evident during the current worldwide pandemic. Computational fluid dynamics (CFD) has been widely used for such predictions, relying on Eulerian–Eulerian (EE) and Eulerian–Lagrangian (EL) models to study particle flow. However, there is a lack of research on industrial factories. In this study, a scaled laboratory in an industrial factory was established for oil mist particles in a machining factory, and oil mist dispersion experiments were conducted under roof exhaust and mixed ventilation conditions. After that, the oil mist concentration distribution in the factory under the same working conditions was calculated by Eulerian and Lagrangian methods, and the corresponding calculation errors and resource consumption were compared. It was found that the simulation results of both methods are acceptable for mixed ventilation and roof exhaust ventilation systems. When there are more vortices in the factory, the Lagrangian method increases the computation time by more than 53% to satisfy the computational accuracy, and the computational error between the Eulerian and Lagrangian methods becomes about 10% larger. For oil mist particles with an aerodynamic diameter of 0.5 μm, both Eulerian and Lagrangian methods have reliable accuracy. Based on the same flow field, the Lagrangian method consumes more than 400 times more computational resources than the Eulerian method. This study can provide a reference for the simulation of indoor particulate transport in industrial factories.

A Lagrangian model which simulates the transport of radionuclides released from nuclear accidents in the western Mediterranean Sea was recently described. This model was developed in spherical coordinates and includes three-dimensional mixing due to turbulence, advection by currents, radioactive decay, and radionuclide exchanges between water and bed sediments. Water circulation was downloaded from the HYCOM global ocean model. Water–sediment interactions were described using a dynamic model based on kinetic transfer coefficients. Mixing, decay, and water–sediment interactions were solved using a stochastic method. Now, a dynamic biological uptake model consisting of four species (phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish) has been integrated within the transport model to be able to assess the effects of a potential accident in biota and fishery regions. The model has been set up for 137Cs and 90Sr due to the radiological relevance of these radionuclides. Several hypothetical accidents were simulated, resulting in 137Cs concentrations in biota significantly higher than background levels. In contrast, 90Sr accumulates in the food chain to a considerably weaker extent.

The transport of radionuclides in the western Mediterranean Sea resulting from hypothetical accidents in a coastal nuclear power plant, and in a vessel with nuclear power or transporting radioactive material, was assessed with a Lagrangian model developed for this kind of accident assessment. Water circulation was obtained from the HYCOM global ocean model. The transport model was developed in spherical coordinates and includes advection by currents, three-dimensional turbulent mixing, radioactive decay, and radionuclide interactions between water and seabed sediments. Age calculations are included as well. A dynamic model based on kinetic transfer coefficients was used to describe these interactions. Mixing, decay, and water/sediment interactions were solved applying a stochastic method. Hypothetical accidents occurring at different moments were simulated to investigate seasonal effects in the fate of radionuclides. In addition, simulations for different radionuclides were carried out to investigate the effects of their different geochemical behaviours. Thus, in the case of a coastal release, 137Cs is transported at long distances from the source, while 239,240Pu stays close to the release point due to its strong reactivity, most of it being quickly fixed to the seabed sediment. In deep waters, in case of a surface release, 239,240Pu spreads over larger areas since sediments are not reached by radionuclides.

A rapid-response Lagrangian model for the use in simulation of the transport of a chemical pollutant in the Arabian/Persian Gulf is described. The model is well suited to the provision of a fast response after an emergency due to an accident or a deliberate spill. It is easy to set up for any situation since only requires the modification of a few input files specifying the pollutant properties and release characteristics. Running times are short, even on a desktop PC, which makes it appropriate for a rapid assessment of a hypothetical accident occurring in the region. Baroclinic circulation was obtained from an HYCOM ocean model, and tides were calculated using a barotropic model. The interactions of pollutants with sediments (uptake/release processes) were described using a dynamic approach based on kinetic transfer coefficients and a stochastic numerical method. Some examples of model applications are shown, showing the influence of the geochemical behaviour of the pollutant in its distribution patterns. [ABSTRACT FROM AUTHOR]

The dynamics and population structure of octopus species in the Gulf of Mexico (GoM) can be studied by analyzing dispersal paralarvae mechanisms. Accordingly, this study focused on understanding octopus paralarval dispersal using numerical modeling. A Lagrangian approach was implemented using the transport model ICHTHYOP and surface currents from a GoM simulation of the HYbrid Coordinate Ocean Model (HYCOM). We modeled the dispersal of four octopus species from the GoM (Octopus "vulgaris", Octopus insularis, Macrotritopus defilippi, and Amphioctopus burryi), considering two regions as the source of larvae in the southern GoM, namely the Yucatan shelf and the Veracruz coastal waters. Additionally, an environmental suitability analysis was incorporated using the maximum entropy (MaxEnt) model to establish potential settlement areas under the influence of the water masses' thermal conditions. The simulation results supported the hypothesis that the abundances recorded in the GoM were influenced by the fertility (egg‐laying) of each species, surface water circulation (the Loop Current, eddies, and wind), and sea surface temperature. Greater dispersal was obtained throughout the GoM for Yucatan species O. "vulgaris", registering the highest settlement rates. In contrast, in Veracruz, O. insularis dispersed and settled only in the western portion of the GoM. The relevance of the ecological descriptors proposed to influence the dispersal and abundance of octopods throughout the GoM's coastal waters are discussed. [ABSTRACT FROM AUTHOR]

Human–robot interaction has extended its application horizon to simplify how human beings interact with each other through a remotely controlled telepresence robot. The fast growth of communication technologies such as 4G and 5G has elevated the potential to establish stable audio–video-data transmission. However, human–robot physical interactions are still challenging regarding maneuverability, controllability, stability, drive layout, and autonomy. Hence, this paper presents a systematic design and control approach based on the customer's needs and expectations of telepresence mobile robots for social interactions. A system model and controller design are developed using the Lagrangian method and linear quadratic regulator, respectively, for different scenarios such as flat surface, inclined surface, and yaw (steering). The robot system is capable of traveling uphill (30 ∘ ) and has a variable height (600–1200 mm). The robot is advantageous in developing countries to fill the skill gaps as well as for sharing knowledge and expertise using a virtual and mobile physical presence. [ABSTRACT FROM AUTHOR]

Knowledge of connectivity among subpopulations is fundamental in the identification of the appropriate geographical scales for stock status evaluation and management, the identification of areas with greater retention rates, and space‐based fisheries management. Here, an integration of hydrodynamic, biological, and habitat models results is used to assess connectivity and support the definition of essential fish habitats (EFH) in the Adriatic Sea, with reference to Nephrops norvegicus, an important benthic commercial resource, the recruitment of which is strongly related to larval dispersal from spawning to recruitment areas. We explored oceanographic and biological connectivity in the Adriatic Sea under a wide and representative variety of oceanographic conditions (winters 2006–2012) by tracking 3D trajectories of larvae released from different areas. We used a Lagrangian model that features a specific larval behavior module with explicit dependence on environmental parameters (i.e., temperature and sediment type) and that is driven by high‐resolution hydrodynamic and meteorological data. The results were used to partition the area in which Nephrops was observed into 20 homogenous management subareas; to assess the connection between spawning, recruitment, and harvesting grounds; and to identify potential subpopulation boundaries as well as the connectivity among the potential subpopulations. The results suggest the presence of at least three distinct subpopulations, which need to be independently managed and conserved, and confirms that the Jabuka‐Pomo pit is the most important spawning area, but alone it cannot sustain Nephrops populations throughout the Adriatic Sea. The results also show the importance to move from particle‐tracking to approaches based on integrated models. [ABSTRACT FROM AUTHOR]

In September 2017, numerous measurement stations recorded large surface concentrations of Ru 106 in Europe. This event was well recorded by various monitoring stations worldwide and offer a valuable framework to compare the modelling strategies deployed to quickly evaluate where the plume goes and with what concentrations. In general, the source and its intensity are not known and hypotheses have to be done. Models have to be fast and accurate: Lagrangian and Eulerian are often used but rarely compared. In this study, the FLEXPART Lagrangian model and the WRF-CHIMERE Eulerian models are used to simulate the emissions, transport and deposition of this source of Ru 106. First, it is shown that the hypothesis of location, timing and intensity of the source is realistic, by comparison to surface measurements. Second, sensitivity analysis performed with the Eulerian model and several transport scheme showed that this model may provide better results than the Lagrangian one. It opens the door to further development, including chemistry and mixing with other pollutants during these specific events. • Long range atmospheric transport in CHIMERE and FLEXPART models yield similar behaviors. • Numerous worldwide measurements allowed the comparison of CHIMERE and FLEXPART at various ranges. • Confusion matrices indicate that CHIMERE performs overall better than FLEXPART on this case. • Numerical diffusion in CHIMERE can be reduced with newly implemented numerical transport schemes. • Conjoint use of both CHIMERE and FLEXPART could be beneficial in future work. [ABSTRACT FROM AUTHOR]

Given the crucial role of low-level circulation in convective events, this study presents a climatological characterization of the moisture sources and sinks associated with the occurrence of nocturnal low-level jets (NLLJs) in South America. Six selected NLLJ cores are identified according to the jet index that considers a vertical wind speed shear of the lower troposphere at 00:00 local time (LT). The Lagrangian FLEXible PARTicle (FLEXPART) model was used to provide the outputs for tracking atmospheric air masses to determine the moisture sources and sinks for the NLLJ cores (Argentina, Venezuela, and the regions of Brazil: south—Brazil-S, southeast—Brazil-SE, north—Brazil-N, and northeast—Brazil-NE). The analysis is based on 37 years (1980–2016) of the ERA-Interim reanalysis. We found that the NLLJ index is stronger in the warm periods of a year (austral spring and summer) for the six selected regions. The NLLJ frequency is also higher in the warm months of the year, except in Brazil-NE where it is very frequent in all months. In Brazil-NE, the NLLJ also persists for 8 or more days, while the other NLLJs frequently persist for 1–2 days. The NLLJs occupy a broad low-level layer (from 1000 to 700 hPa) and exhibit a mean speed between 7 and 12 ms–1, which peaks mostly at 900 hPa. The moisture transport for each NLLJ shows that in addition to the intense local moisture sources, the NLLJs in Argentina and Brazil-S receive moisture from the tropical-subtropical South Atlantic Ocean and the Amazon basin, while the tropical-subtropical South Atlantic Ocean is the main moisture source for the NLLJ in Brazil-SE. Both moisture sources and sinks are stronger in the austral summer and fall. The NLLJ in Brazil receives moisture from the tropical South Atlantic (TSA) Ocean, which has weak seasonality. The moisture sources for the NLLJs in Brazil-N and Venezuela come from the tropical North Atlantic (TNA) Ocean in the austral summer and fall, while the TSA Ocean appears as an additional moisture source in the austral winter. This research contributes to improving our understanding of the NLLJs and their role in transporting moisture and controlling precipitation over the continent according to the seasons of a year, helping to improve seasonal climate forecasting.

The constitutive model and its pertinent set of parameters are important input data in finite element modeling to define the behavior of Ti6Al4V during machining process. The present work focusses on comparing different constitutive models and the parameters sets available in literatures and investigating the quality of the predictions when varying uncut chip thickness (40 µm, 60 µm, 100 µm and 280 µm). In addition, temperature-dependent strain hardening factor along with strain softening phenomenon based reconstructed material model is proposed. The results from the numerical simulations are compared with experimental results available in literature. The comparison shows that the force values are highly influenced by constitutive models and the choice of parameters sets, whereas the chip morphologies are mainly influenced by the uncut chip thickness and constitutive models. This work justifies the need for an appropriate set of parameters and constitutive model that replicate the machining behavior of Ti6Al4V alloy for different cutting conditions. [ABSTRACT FROM AUTHOR]

This work aims to evaluate the impact of Lagrangian and Coupled Eulerian-Lagrangian (CEL) approaches used in the orthogonal cutting simulation of Inconel 718 nickel-based superalloy on the simulated forces, cutting temperature, chip morphology, chip compression ratio, and residual stresses on the surface and subsurface. Machining models using these approaches are developed, and they include a recent proposed constitutive material model considering the effects of strain hardening, strain-rate, state of stress, and temperature. The simulated results are compared to experimental ones, in order to determine which approach simulates better the orthogonal cutting of Inconel 718. [ABSTRACT FROM AUTHOR]

Flow-induced hemolysis remains a concern for blood-contacting devices, and computer-based prediction of hemolysis could facilitate faster and more economical refinement of such devices. While evaluation of convergence of velocity fields obtained by computational fluid dynamics (CFD) simulations has become conventional, convergence of hemolysis calculations is also essential. In this paper, convergence of the power-law hemolysis model is compared for simple flows, including pathlines with exponentially increasing and decreasing stress, in gradually expanding and contracting Couette flows, in a sudden radial expansion and in the Food and Drug Administration (FDA) channel. In the exponential cases, convergence along a pathline required from one to tens of thousands of timesteps, depending on the exponent. Greater timesteps were required for rapidly increasing (large exponent) stress and for rapidly decreasing (small exponent) stress. Example pathlines in the Couette flows could be fit with exponential curves, and convergence behavior followed the trends identified from the exponential cases. More complex flows, such as in the radial expansion and the FDA channel, increase the likelihood of encountering problematic pathlines. For the exponential cases, comparison of converged hemolysis values with analytical solutions demonstrated that the error of the converged solution may exceed 10% for both rapidly decreasing and rapidly increasing stress. [ABSTRACT FROM AUTHOR]

Short-term events are one of the specific aspects that differentiate odour nuisance problems from conventional air quality pollutants. Atmospheric dispersion modelling has been considered the gold standard to realise odour impact assessments and to calculate separation distances. Most of these models provide predictions of concentrations of a pollutant in ambient air on an hourly basis. Even when the hourly mean odour concentration is lower than the perception threshold, concentration peaks above the threshold may occur during this period. The constant peak-to-mean factor is nowadays the most widespread method for evaluating short-term concentrations from the long-term ones. Different approaches have been proposed in the scientific literature to consider non-constant peak-to-mean factors. Two prominent approaches to do so are the i) variable peak-to-mean factor which considers the distance from the source and atmospheric stability and the ii) concentration-variance transport. In this sense, the aim of this work is to compare the results of three different freely available dispersion models (namely, CALPUFF, LAPMOD and GRAL), which implement three distinct ways to evaluate the short-term concentration values. Two sites, one in Austria and the other in Italy, were selected for the investigation.Dispersion model results were compared and discussed both in terms of long-term (hourly) concentrations and short-term. An important outcome of this work is that the dispersion models provided more equivalent results for hourly mean concentrations, in particular in the far-field. On the contrary, the method to evaluate short-term concentrations can deliver disparate results, thereby revealing a potential risk of poor assessment conclusions.The utilistion of a multiangle methodological approach (dispersion models, study site locations, algorithms to incorporate short-term concentrations) allowed providing useful information for future studies and policymaking in this field. Accordingly, our findings call for awareness on how the use of a particular dispersion model and its sub-hourly peak calculation method can affect odour impact assessment conclusions and compliance demonstrations.

The Arctic Ocean has suffered extreme reductions in sea ice in recent decades, and these observed changes suggest implications in terms of moisture transport. The Arctic region is a net sink of moisture in terms of the total hydrological cycle, however, its role as a moisture source for specific regions has not been extensively studied. Our results show that 80% of the moisture supply from the Arctic contributes to precipitation over itself, representing about 8% of the global moisture supply to the Arctic, the remaining 20% is distributed in the surrounding. A reduction in the sea ice extent could make the Arctic Ocean a slightly higher source of moisture to itself or to the surrounding areas. The analysis of the areas affected by Arctic moisture transport is important for establishing those areas vulnerable to change in a framework of a growing sea ice decline. To this end, the Lagrangian model FLEXPART was used in this work to establish the main sinks for the Arctic Ocean, focusing on the moisture transport from this region. The results suggest that most of the moisture loss occurs locally over the Arctic Ocean itself, especially in summer. Some moisture contribution from the Arctic Ocean to continental areas in North America and Eurasia is also noted in autumn and winter especially from Central Arctic, the East Siberian Sea, the Laptev, Kara, Barents, East Greenland and Bering Seas, and the Sea of Okhotsk.

The influence of particle concentration on the drag force of a particle deserves attention when using the Lagrangian Particle Tracking methods for the prediction of industrial type gas-solid flows. The Lagrangian approach is best suited to applications where the solids volume fraction is low, and the effect of particle concentration can be ignored. In the present work, a 3D time dependent numerical analysis is performed to study the effect of Lagrangian model improvements to replicate experimental studies of straight horizontal pipe flow and flow through a 90° horizontal-to-vertical bend. The present predictions are compared with published experimental data of Tsuji and Morikawa (1982) , and Yilmaz (1997). Special attention is paid to influence of particle mass-flow rates and conveying velocity on the particle motion within the system. This study used a CFX-4 package, where the ability to modify the code was necessary to include particle model improvements. These improvements included implementing a newly drag force model developed as a part of this research work. Particle-wall collision and particle-particle collision models developed by Sommerfeld (1992) , and Sommerfeld (2001) are also implemented in the CFD model. The standard k–ε dispersed turbulence model was utilized as the predictions for the gas phase only gave similar predicted axial velocity compared to the more computationally demanding Reynolds stress model. The results showed that the inclusion of the various improvements lead to reasonable predicted particle velocities in both the upper and lower regions of the straight horizontal pipe which denote the dilute and dense regions respectively. It was also found that the inclusion of the rough-wall particle wall collision model decreases the axial particle velocity in the lower region where the bulk of the particle wall collisions occur. While the inclusion of the particle collision models tends to disperse the particles away from the lower region resulting in a less dense lower section and a distinctly more homogenous particle distribution compared with the standard model predictions. Further, the increase in particle concentration leads to a reduction in axial velocity due to a loss of momentum through particle-wall and particle-particle collisions. Finally, the improved CFD model best predicted both the reduction and increase in the particle velocities in the different regions. [ABSTRACT FROM AUTHOR]