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Journal articles on the topic 'Tracers dispersion'

Author: Grafiati

Published: 10 March 2023

Last updated: 31 July 2025

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1

Istók, Balázs, and Gergely Kristóf. "Dispersion and Travel Time of Dissolved and Floating Tracers in Urban Sewers." Slovak Journal of Civil Engineering 22, no. 1 (2014): 1–8. http://dx.doi.org/10.2478/sjce-2014-0001.

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Abstract Environmental impacts of oil spills affecting urban sewage networks can be eliminated if timely intervention is taken. The design of such actions requires knowledge of the transport of surface pollutants in open channels. In this study we investigated the travel time and dispersion of pollutants by means of tracer experiments in sewage networks and a creek. The travel time of surface tracers has been found to be significantly shorter than that of a bulk flow tracer. The ratio of the travel times of a bulk flow tracer and surface tracers agreed with the known correlations obtained for

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Ayuba, Ibrahim, Lateef T. Akanji, Jefferson L. Gomes, and Gabriel K. Falade. "Investigation of Drift Phenomena at the Pore Scale during Flow and Transport in Porous Media." Mathematics 9, no. 19 (2021): 2509. http://dx.doi.org/10.3390/math9192509.

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This paper reports an analytical study conducted to investigate the behaviour of tracers undergoing creeping flow between two parallel plates in porous media. A new coupled model for the characterisation of fluid flow and transport of tracers at pore scale is formulated. Precisely, a weak-form solution of radial transport of tracers under convection–diffusion-dominated flow is established using hypergeometric functions. The velocity field associated with the radial transport is informed by the solution of the Stokes equations. Channel thickness as a function of velocities, maximum Reynolds num

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3

Lee, Mei-Man, A. J. George Nurser, Andrew C. Coward, and Beverly A. de Cuevas. "Effective Eddy Diffusivities Inferred from a Point Release Tracer in an Eddy-Resolving Ocean Model." Journal of Physical Oceanography 39, no. 4 (2009): 894–914. http://dx.doi.org/10.1175/2008jpo3902.1.

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Abstract This study uses tracer experiments in a global eddy-resolving ocean model to examine two diagnostic methods for inferring effective eddy isopycnic diffusivity from point release tracers. The first method is based on the growth rate of the area occupied by the tracers (the equivalent variance). During the period when tracer dispersion is dominated by stirring, the equivalent variance is found to increase at a rate between the second power law (for a pure shearing flow regime) and the exponential law (for a pure stretching flow regime). The second method is based on the length of the tr

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4

Davis, P. M., T. C. Atkinson, and T. M. L. Wigley. "Longitudinal dispersion in natural channels: 2. The roles of shear flow dispersion and dead zones in the River Severn, U.K." Hydrology and Earth System Sciences 4, no. 3 (2000): 355–71. http://dx.doi.org/10.5194/hess-4-355-2000.

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Abstract. The classical one-dimensional advection-diffusion equation (ADE) gives an inadequate description of tracer cloud evolution in the River Severn, U.K. A solute transport model incorporating the effects of tracer storage in dead zones is presented in which the channel is conceived as being divided into two parallel regions. The bulk flow region occurs in the central part. Its longitudinal dispersive properties are described by the ADE. Adjacent to this, an additional cross-sectional area is defined in which tracer can be stored temporarily in regions of slowly moving water called dead z

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5

Yuan (原), Yuxuan (宇轩), Mark R. Krumholz, and Blakesley Burkhart. "Understanding biases in measurements of molecular cloud kinematics using line emission." Monthly Notices of the Royal Astronomical Society 498, no. 2 (2020): 2440–55. http://dx.doi.org/10.1093/mnras/staa2432.

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ABSTRACT Molecular line observations using a variety of tracers are often used to investigate the kinematic structure of molecular clouds. However, measurements of cloud velocity dispersions with different lines, even in the same region, often yield inconsistent results. The reasons for this disagreement are not entirely clear, since molecular line observations are subject to a number of biases. In this paper, we untangle and investigate various factors that drive linewidth measurement biases by constructing synthetic position–position–velocity cubes for a variety of tracers from a suite of se

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HASZPRA, TÍMEA, PÉTER KISS, TAMÁS TÉL, and IMRE M. JÁNOSI. "ADVECTION OF PASSIVE TRACERS IN THE ATMOSPHERE: BATCHELOR SCALING." International Journal of Bifurcation and Chaos 22, no. 10 (2012): 1250241. http://dx.doi.org/10.1142/s0218127412502410.

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Extensive numerical experiments are performed on tracer dispersion in global reanalysis wind fields. Particle trajectories are computed both along an isobaric (500 hPa) and an isentropic (315 K) surface in a time interval of one year. Besides mean quantities such as advection of the center of mass and growth of tracer clouds, special attention is paid to the evaluation of particle pair separation dynamics. The characteristic behavior for intermediate time scales is Batchelor's dispersion along both surfaces, where the zonal extent of the tracer cloud increases linearly in time. The long-time e

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7

Richards, K. J., Y. Jia, and C. F. Rogers. "Dispersion of Tracers by Ocean Gyres." Journal of Physical Oceanography 25, no. 5 (1995): 873–87. http://dx.doi.org/10.1175/1520-0485(1995)025<0873:dotbog>2.0.co;2.

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8

Smith, Ronald. "Effect of islands upon dispersion in rivers." Journal of Fluid Mechanics 292 (June 10, 1995): 249–70. http://dx.doi.org/10.1017/s0022112095001510.

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A general formulation is given for the dispersion of conservative tracers in steady flow in multi-connected channels. A multi-index is used to distinguish the different routes for tracer between the source and the observation position. For each route exact formulae are obtained for the time integral, time centroid, and cross-channel average of the temporal variance. The total concentration is the superposition of the contributions from the different routes.

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9

Kumar, Parveen, Joshua Tamayo, Ruei-Feng Shiu, Wei-Chun Chin, and Arvind Gopinath. "Size-Dependent Diffusion and Dispersion of Particles in Mucin." Polymers 15, no. 15 (2023): 3241. http://dx.doi.org/10.3390/polym15153241.

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Mucus, composed significantly of glycosylated mucins, is a soft and rheologically complex material that lines respiratory, reproductive, and gastrointestinal tracts in mammals. Mucus may present as a gel, as a highly viscous fluid, or as a viscoelastic fluid. Mucus acts as a barrier to the transport of harmful microbes and inhaled atmospheric pollutants to underlying cellular tissue. Studies on mucin gels have provided critical insights into the chemistry of the gels, their swelling kinetics, and the diffusion and permeability of molecular constituents such as water. The transport and dispersi

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10

Govender, Elaine, Athanasios Kotsiopoulos, and Sue T. L. Harrison. "A Study of Permeability and Diffusion at the Agglomerate-Scale in Heap (Bio)Leaching Systems." Advanced Materials Research 1130 (November 2015): 316–20. http://dx.doi.org/10.4028/www.scientific.net/amr.1130.316.

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Multiple mini-column reactors, loaded with identically constructed ore samples representing grab samples of a larger heap, were used to study the behaviour of solution tracers to elucidate solution diffusion, dispersion and transport. The tracers were either introduced to the ore bed as a pulse, included during agglomeration of the ore or introduced to the system by submerging the ore bed. These methods of tracer introduction allowed for the characterisation of flow interchange in unsteady state systems. The resulting concentration-time distribution curves were analysed to allow characterisati

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11

Pastore, Claudio, Eric Weber, Frédéric Doumenc, Pierre-Yves Jeannin, and Marc Lütscher. "Dispersion of artificial tracers in ventilated caves." International Journal of Speleology 53, no. 1 (2024): 51–62. http://dx.doi.org/10.5038/1827-806x.53.1.2497.

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Artificial CO2 was used as a tracer along ventilated karst conduits to infer airflow and investigate tracer dispersion. In the karst vadose zone, cave ventilation is an efficient mode of transport for heat, gases and aerosols and thus drives the spatial distribution of airborne particles. Modelling this airborne transport requires geometrical and physical parameters of the conduit system, including the cross-sectional areas, the airflow and average air speed, as well as the longitudinal dispersion coefficient which describes the spreading of a solute. Four gauging tests were carried out in one

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12

Badin, Gualtiero, Amit Tandon, and Amala Mahadevan. "Lateral Mixing in the Pycnocline by Baroclinic Mixed Layer Eddies." Journal of Physical Oceanography 41, no. 11 (2011): 2080–101. http://dx.doi.org/10.1175/jpo-d-11-05.1.

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Abstract Using a process study model, the effect of mixed layer submesoscale instabilities on the lateral mixing of passive tracers in the pycnocline is explored. Mixed layer eddies that are generated from the baroclinic instability of a front within the mixed layer are found to penetrate into the pycnocline leading to an eddying flow field that acts to mix properties laterally along isopycnal surfaces. The mixing of passive tracers released on such isopycnal surfaces is quantified by estimating the variance of the tracer distribution over time. The evolution of the tracer variance reveals tha

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13

Farazmand, Mohammad, and Themistoklis Sapsis. "Surface Waves Enhance Particle Dispersion." Fluids 4, no. 1 (2019): 55. http://dx.doi.org/10.3390/fluids4010055.

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We study the horizontal dispersion of passive tracer particles on the free surface of gravity waves in deep water. For random linear waves with the JONSWAP spectrum, the Lagrangian particle trajectories are computed using an exact nonlinear model known as the John–Sclavounos equation. We show that the single-particle dispersion exhibits an unusual super-diffusive behavior. In particular, for large times t, the variance of the tracer ⟨ | X ( t ) | 2 ⟩ increases as a quadratic function of time, i.e., ⟨ | X ( t ) | 2 ⟩ ∼ t 2 . This dispersion is markedly faster than Taylor’s single-particle dispe

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Davis, P. M., and T. C. Atkinson. "Longitudinal dispersion in natural channels: 3. An aggregated dead zone model applied to the River Severn, U.K." Hydrology and Earth System Sciences 4, no. 3 (2000): 373–81. http://dx.doi.org/10.5194/hess-4-373-2000.

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Abstract. An Aggregated Dead Zone (ADZ) model is presented for longitudinal dispersion of tracer in river channels, in which the channel cross-section is divided into two parallel regions: the bulk flow and dead zone storage. Tracer particles in the bulk flow are assumed to obey plug-flow advection at the discharge velocity U without any mixing effects. The dispersive properties of the model are completely embodied in the residence time for tracer storage in the dead zone. The model provides an excellent description and prediction of empirical concentration-time distributions, for times t <

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15

Fast, Jerome D., K. Jerry Allwine, Russell N. Dietz, Kirk L. Clawson, and Joel C. Torcolini. "Dispersion of Perfluorocarbon Tracers within the Salt Lake Valley during VTMX 2000." Journal of Applied Meteorology and Climatology 45, no. 6 (2006): 793–812. http://dx.doi.org/10.1175/jam2371.1.

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Abstract Six perfluorocarbon tracer experiments were conducted in Salt Lake City, Utah, during October 2000 as part of the Vertical Transport and Mixing (VTMX) field campaign. Four tracers were released at different sites to obtain information on dispersion during stable conditions within down-valley flow, canyon outflow, and interacting circulations in the downtown area. Some of the extensive tracer data that were collected are presented in the context of the meteorological field campaign measurements. Tracer measurements at building-top sites in the downtown area and along the lower slopes o

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16

Faller, Alan J. "A random-flight evaluation of the constants of relative dispersion in idealized turbulence." Journal of Fluid Mechanics 316 (June 10, 1996): 139–61. http://dx.doi.org/10.1017/s002211209600047x.

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In the idealized problem of homogeneous isotropic stationary inertial-range turbulence the rate of relative dispersion of an ensemble of tracer pairs can be characterized by a constant C0. In order to compute this constant with random-flight equations, however, it is necessary first to know the values of two other constants, C1 and C2, that occur in the two-particle velocity-component relations of Lagrangian tracers (Faller 1992).C1 and C2 are found by an elaborate trial and error procedure in a new two-tracer random-flight model of dispersion that matches input and output values of these two

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17

Lajeunesse, Eric, Olivier Devauchelle, and François James. "Advection and dispersion of bed load tracers." Earth Surface Dynamics 6, no. 2 (2018): 389–99. http://dx.doi.org/10.5194/esurf-6-389-2018.

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Abstract. We use the erosion–deposition model introduced by Charru et al. (2004) to numerically simulate the evolution of a plume of bed load tracers entrained by a steady flow. In this model, the propagation of the plume results from the stochastic exchange of particles between the bed and the bed load layer. We find a transition between two asymptotic regimes. The tracers, initially at rest, are gradually set into motion by the flow. During this entrainment regime, the plume is strongly skewed in the direction of propagation and continuously accelerates while spreading nonlinearly. With time

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18

Punanova, A., P. Caselli, J. E. Pineda, et al. "Kinematics of dense gas in the L1495 filament." Astronomy & Astrophysics 617 (September 2018): A27. http://dx.doi.org/10.1051/0004-6361/201731159.

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Context. Nitrogen bearing species, such as NH3, N2H+, and their deuterated isotopologues show enhanced abundances in CO-depleted gas, and thus are perfect tracers of dense and cold gas in star-forming regions. The Taurus molecular cloud contains the long L1495 filament providing an excellent opportunity to study the process of star formation in filamentary environments. Aims. We study the kinematics of the dense gas of starless and protostellar cores traced by the N2D+(2–1), N2H+(1–0), DCO+(2–1), and H13CO+(1–0) transitions along the L1495 filament and the kinematic links between the cores and

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19

Rodriguez, A., A. Sánchez-Arcilla, J. M. Redondo, E. Bahia, and J. P. Sierra. "Pollutant dispersion in the nearshore region: modelling and measurements." Water Science and Technology 32, no. 9-10 (1995): 169–78. http://dx.doi.org/10.2166/wst.1995.0682.

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Some results on pollutant dispersion modelling and tracer measurements for the Mediterranean Spanish coast are presented. Two hydrodynamic models have been used to simulate wind and wave induced circulation in the nearshore and surf zones respectively. A “near field” model has been used in order to simulate the initial conditions for the local “far field” dispersion model. Two study cases are presented: The first one shows the mixing of conservative tracers in a Mediterranean surf zone from an experimental and numerical models used to predict bacterial dispersion from the main sea outfalls of

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20

Aniyan, S., A. A. Ponomareva, K. C. Freeman, et al. "Resolving the Disc–Halo Degeneracy – II: NGC 6946." Monthly Notices of the Royal Astronomical Society 500, no. 3 (2020): 3579–93. http://dx.doi.org/10.1093/mnras/staa3106.

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ABSTRACT The mass-to-light ratio (M/L) is a key parameter in decomposing galactic rotation curves into contributions from the baryonic components and the dark halo of a galaxy. One direct observational method to determine the disc M/L is by calculating the surface mass density of the disc from the stellar vertical velocity dispersion and the scale height of the disc. Usually, the scale height is obtained from near-IR studies of edge-on galaxies and pertains to the older, kinematically hotter stars in the disc, while the vertical velocity dispersion of stars is measured in the optical band and

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21

Landel, Julien R., C. P. Caulfield, and Andrew W. Woods. "Streamwise dispersion and mixing in quasi-two-dimensional steady turbulent jets." Journal of Fluid Mechanics 711 (September 12, 2012): 212–58. http://dx.doi.org/10.1017/jfm.2012.388.

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AbstractWe investigate experimentally and theoretically the streamwise transport and dispersion properties of steady quasi-two-dimensional plane turbulent jets discharged vertically from a slot of width $d$ into a fluid confined between two relatively close rigid boundaries with gap $W\ensuremath{\sim} O(d)$. We model the evolution in time and space of the concentration of passive tracers released in these jets using a one-dimensional time-dependent effective advection–diffusion equation. We make a mixing length hypothesis to model the streamwise turbulent eddy diffusivity such that it scales

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22

Atkinson, T. C., and P. M. Davis. "Longitudinal dispersion in natural channels: l. Experimental results from the River Severn, U.K." Hydrology and Earth System Sciences 4, no. 3 (2000): 345–53. http://dx.doi.org/10.5194/hess-4-345-2000.

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Abstract. Abstract: A tracer experiment using Rhodamine WT dye was carried out to measure longitudinal dispersion in a 14-km reach of the River Severn in Wales, U.K. The river’s discharge was measured at six points and the depth, width and cross-sectional area were measured at 86 points along the test reach. The channel geometry was close to being statistically uniform. Discharge and velocity were both nearly constant. Dye concentrations were recorded at stations between 210 and 13775 m downstream of injection. Dye was injected over a short interval as a near-uniform line source across the cha

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23

Jullien, Marie-Caroline, Patrizia Castiglione, and Patrick Tabeling. "Experimental Observation of Batchelor Dispersion of Passive Tracers." Physical Review Letters 85, no. 17 (2000): 3636–39. http://dx.doi.org/10.1103/physrevlett.85.3636.

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24

Rotenberg, B., I. Pagonabarraga, and D. Frenkel. "Dispersion of charged tracers in charged porous media." EPL (Europhysics Letters) 83, no. 3 (2008): 34004. http://dx.doi.org/10.1209/0295-5075/83/34004.

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25

Kim, Keunyong, Hong Thi My Tran, Kyu-Min Song, et al. "Near-Surface Dispersion and Current Observations Using Dye, Drifters, and HF Radar in Coastal Waters." Remote Sensing 16, no. 11 (2024): 1985. http://dx.doi.org/10.3390/rs16111985.

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This study explores the near-surface dispersion mechanisms of contaminants in coastal waters, leveraging a comprehensive method that includes using dye and drifters as tracers, coupled with diverse observational platforms like drones, satellites, in situ sampling, and HF radar. The aim is to deepen our understanding of surface currents’ impact on contaminant dispersion, thereby improving predictive models for managing environmental incidents such as pollutant releases. Rhodamine WT dye, chosen for its significant fluorescent properties and detectability, along with drifter data, allowed us to

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26

Braconnier, Benjamin, Christophe Preux, Frédéric Douarche, and Bernard Bourbiaux. "MUSCL scheme for Single Well Chemical Tracer Test simulation, design and interpretation." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 74 (2019): 10. http://dx.doi.org/10.2516/ogst/2018090.

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Our paper presents an improved numerical scheme to simulate Single Well Chemical Tracer Test (SWCTT) method. SWCTT is mainly applied to determine the residual oil saturation of reservoirs. It consists in injecting an aqueous slug of a primary tracer into the reservoir formation and displacing it at a certain distance from the well. This tracer is partly miscible with oil on the one hand, and generates in situ a secondary tracer on the other hand. As a consequence, a shift is observed between the primary and the secondary tracers arrival times when production is resumed. This time shift is used

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27

Keating, Shane R., K. Shafer Smith, and Peter R. Kramer. "Diagnosing Lateral Mixing in the Upper Ocean with Virtual Tracers: Spatial and Temporal Resolution Dependence." Journal of Physical Oceanography 41, no. 8 (2011): 1512–34. http://dx.doi.org/10.1175/2011jpo4580.1.

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Abstract Several recent studies diagnose lateral stirring and mixing in the upper ocean using altimetry-derived velocity fields to advect “virtual” particles and fields offline. However, the limited spatiotemporal resolution of altimetric maps leads to errors in the inferred diagnostics, because unresolved scales are necessarily imperfectly modeled. The authors examine a range of tracer diagnostics in two models of baroclinic turbulence: the standard Phillips model, in which dispersion is controlled by large-scale eddies, and the Eady model, where dispersion is determined by local scales of mo

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Rabah, Amal, Manuel Marcoux, and David Labat. "Effects of Geometry on Artificial Tracer Dispersion in Synthetic Karst Conduit Networks." Water 15, no. 22 (2023): 3885. http://dx.doi.org/10.3390/w15223885.

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This paper presents the modeling results of tracer test simulations performed using COMSOL Multiphysics (version 6.1), a powerful software for multiphysics simulation. The simulations consist of the propagation of artificial tracers injected into different model configurations. This study is based on computational fluid dynamics (CFDs), which allows us to take into consideration the turbulent regime of the water flow in conduits. The objective of this contribution is to identify the relationship between the tracer dynamics and the geometric parameters of synthetic karstic systems via a systema

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Espa, Stefania, G. Querzoli, and A. Cenedese. "Dispersion of passive tracers in a confined convective flow." European Journal of Mechanics - B/Fluids 20, no. 4 (2001): 525–40. http://dx.doi.org/10.1016/s0997-7546(01)01125-6.

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Gudiksen, Paul H., and Donald L. Shearer. "The Dispersion of Atmospheric Tracers in Nocturnal Drainage Flows." Journal of Applied Meteorology 28, no. 7 (1989): 602–8. http://dx.doi.org/10.1175/1520-0450(1989)028<0602:tdoati>2.0.co;2.

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Yi, Shu Ping, Hai Yi Ma, and Hua An Wang. "A Preliminary Study on the Transport Behavior for a Potential Disposal Site of LILW in Southern China." Advanced Materials Research 356-360 (October 2011): 1445–53. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.1445.

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Near surface disposal of low and intermediate level radioactive waste (LILW) requires a detailed site investigation of the potential sites, in which the transport behavior of solutes in the groundwater system is one of the key processes that needed to be addressed. An investigation is undertaking for the disposal of LILW at a potential site in Southern China. In-situ test have been conducted to study the hydrogeologic characteristics of the site. Firstly, tests including pit permeability tests, injecting tests, water pressure tests, pumping tests and laboratory permeability tests have been per

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Yu, Li-Ming, Wei-Hao Bian, Chan Wang, Bi-Xuan Zhao, and Xue Ge. "Calibration of the virial factor f in supermassive black hole masses of reverberation-mapped AGNs." Monthly Notices of the Royal Astronomical Society 488, no. 2 (2019): 1519–34. http://dx.doi.org/10.1093/mnras/stz1766.

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ABSTRACT Using a compiled sample of 34 broad-line active galactic nuclei (AGNs) with measured H β time lags from the reverberation mapping (RM) method and measured bulge stellar velocity dispersions σ*, we calculate the virial factor f by assuming that the RM AGNs intrinsically obey the same MBH−σ* relation as quiescent galaxies, where MBH is the mass of the supermassive black hole (SMBH). Considering four tracers of the velocity of the broad-line regions (BLRs), i.e. the H β line width or line dispersion from the mean or rms spectrum, there are four kinds of the factor f. Using the H β full w

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Croze, Ottavio A., Gaetano Sardina, Mansoor Ahmed, Martin A. Bees, and Luca Brandt. "Dispersion of swimming algae in laminar and turbulent channel flows: consequences for photobioreactors." Journal of The Royal Society Interface 10, no. 81 (2013): 20121041. http://dx.doi.org/10.1098/rsif.2012.1041.

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Shear flow significantly affects the transport of swimming algae in suspension. For example, viscous and gravitational torques bias bottom-heavy cells to swim towards regions of downwelling fluid (gyrotaxis). It is necessary to understand how such biases affect algal dispersion in natural and industrial flows, especially in view of growing interest in algal photobioreactors. Motivated by this, we here study the dispersion of gyrotactic algae in laminar and turbulent channel flows using direct numerical simulation (DNS) and a previously published analytical swimming dispersion theory. Time-reso

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HAMAKI, Michihiro, Toshiki IWASAKI, Takuya INOUE, Daisuke SATO, Tamaki SUMNER, and Yasuyuki SHIMIZU. "EXPERIMENT AND NUMERICAL SIMULATION OF ADVECTION-DISPERSION OF BEDLOAD TRACERS." Journal of Japan Society of Civil Engineers, Ser. B1 (Hydraulic Engineering) 74, no. 4 (2018): I_1033—I_1038. http://dx.doi.org/10.2208/jscejhe.74.i_1033.

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35

Pizzuto, James E. "Dispersion of dyed sand tracers in an oscillatory flow field." Journal of Geophysical Research 92, no. C2 (1987): 1923. http://dx.doi.org/10.1029/jc092ic02p01923.

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Wagner, Gregory L., Glenn Flierl, Raffaele Ferrari, et al. "Squeeze Dispersion and the Effective Diapycnal Diffusivity of Oceanic Tracers." Geophysical Research Letters 46, no. 10 (2019): 5378–86. http://dx.doi.org/10.1029/2019gl082458.

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CHATWIN, P. C., N. T. HAJIAN, N. MOLE, and C. D. JONES. "Investigations on the Atmospheric Dispersion of Clouds Containing Charged Tracers." IMA Journal of Applied Mathematics 42, no. 2 (1989): 97–117. http://dx.doi.org/10.1093/imamat/42.2.97.

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Croze, Ottavio A., Rachel N. Bearon, and Martin A. Bees. "Gyrotactic swimmer dispersion in pipe flow: testing the theory." Journal of Fluid Mechanics 816 (March 7, 2017): 481–506. http://dx.doi.org/10.1017/jfm.2017.90.

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Suspensions of microswimmers are a rich source of fascinating new fluid mechanics. Recently we predicted the active pipe flow dispersion of gyrotactic microalgae, whose orientation is biased by gravity and flow shear. Analytical theory predicts that these active swimmers disperse in a markedly distinct manner from passive tracers (Taylor dispersion). Dispersing swimmers display non-zero drift and effective diffusivity that is non-monotonic with Péclet number. Such predictions agree with numerical simulations, but hitherto have not been tested experimentally. Here, to facilitate comparison, we

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Choudhury, Spandan, Jaime E. Pineda, Paola Caselli, et al. "Transition from coherent cores to surrounding cloud in L1688." Astronomy & Astrophysics 648 (April 2021): A114. http://dx.doi.org/10.1051/0004-6361/202039897.

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Context. Stars form in cold dense cores showing subsonic velocity dispersions. The parental molecular clouds display higher temperatures and supersonic velocity dispersions. The transition from core to cloud has been observed in velocity dispersion, but temperature and abundance variations are unknown. Aims. We aim to measure the temperature and velocity dispersion across cores and ambient cloud in a single tracer to study the transition between the two regions. Methods. We use NH3 (1,1) and (2,2) maps in L1688 from the Green Bank Ammonia Survey, smoothed to 1′, and determine the physical prop

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Yan, Sheng, Zhili Zou, and Zaijin You. "Eulerian Description of Wave-Induced Stokes Drift Effect on Tracer Transport." Journal of Marine Science and Engineering 10, no. 2 (2022): 253. http://dx.doi.org/10.3390/jmse10020253.

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The wave-induced Stokes drift plays a significant role on mass/tracer transport in the ocean and the evolution of coastal morphology. The tracer advection diffusion equation needs to be modified for Eulerian ocean models to properly account for the surface wave effects. The Eulerian description of Stokes drift effect on the tracer transport is derived in this study to show that this effect can be accounted for automatically in the wave-averaged advection-diffusion equation. The advection term in this equation is the wave-averaged concentration flux produced by the interaction between fluctuati

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Pietrzak, Damian, Jarosław Kania, Ewa Kmiecik, and Katarzyna Wątor. "Identification of transport parameters of chlorides in different soils on the basis of column studies." Geologos 25, no. 3 (2019): 225–29. http://dx.doi.org/10.2478/logos-2019-0024.

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Abstract Knowledge of transport patterns of chemicals in groundwater is essential for environmental assessment of their potential impact. In the present study, the mobility of a chloride tracer injected into three different soils was investigated, using column experiments. The column tests were performed under steady-state conditions to determine parameters of chloride migration through soils. Based on breakthrough curves, pore-water velocity, dispersion coefficient and dispersivity constant were calculated for each soil sample using CXTFIT/STANMOD software. Pore-water velocity was in the rang

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Jung, Minji, Woong June Chung, Minki Sung, Seongmin Jo, and Jinkwan Hong. "Analysis of Infection Transmission Routes through Exhaled Breath and Cough Particle Dispersion in a General Hospital." International Journal of Environmental Research and Public Health 19, no. 5 (2022): 2512. http://dx.doi.org/10.3390/ijerph19052512.

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Identifying infection transmission routes in hospitals may prevent the spread of respiratory viruses and mass infections. Most previous related research focused on the air movement of passive tracers, which typically represent breathing. In this study, particle evaporation and dispersions with various particle sizes were applied to evaluate particle movement because of breathing and coughing using computational fluid dynamics (CFD) simulations. Pyeongtaek St. Mary Hospital, where a Middle East respiratory syndrome (MERS) index patient infected several patients on the same floor, was used for a

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Vázquez, Tarrío Daniel, Alain Recking, Frédéric Liébault, Michal Tal, and Rosana Menéndez-Duarte. "Particle transport in gravel-bed rivers: Revisiting passive tracer data." Earh Surface Processes and Landforms 44, no. 1 (2019): 112–28. https://doi.org/10.1002/esp.4484.

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Data from tracer experiments were compiled and analysed in order to explore the role of geomorphological, hydrological and sedimentological constraints on fluvial gravel transport in gravel-bed rivers. A large data set from 217 transport episodes of tagged stones were compiled from 33 scientific papers. Our analyses showed that while magnitude of peak discharge is a major control on gravel transport and mobility, tracer travel distances show some scale dependence on the morphological configuration of the channel. Our results also highlight differences in the way tracers are displaced between s

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Massardier, Valérie, Molka Louizi, Elisabeth Maris, and Daniel Froelich. "High shear dispersion of tracers in polyolefins for improving their detection." Polímeros 25, no. 5 (2015): 466–76. http://dx.doi.org/10.1590/0104-1428.1974.

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Artale, V., G. Boffetta, A. Celani, M. Cencini, and A. Vulpiani. "Dispersion of passive tracers in closed basins: Beyond the diffusion coefficient." Physics of Fluids 9, no. 11 (1997): 3162–71. http://dx.doi.org/10.1063/1.869433.

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Müller, W. C., and A. Busse. "Diffusion and dispersion of passive tracers: Navier-Stokes vs. MHD turbulence." Europhysics Letters (EPL) 78, no. 1 (2007): 14003. http://dx.doi.org/10.1209/0295-5075/78/14003.

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Jullien, Marie-Caroline. "Dispersion of passive tracers in the direct enstrophy cascade: Experimental observations." Physics of Fluids 15, no. 8 (2003): 2228–37. http://dx.doi.org/10.1063/1.1585030.

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Faller, Alan J., and Stephen J. Auer. "The Roles of Langmuir Circulations in the Dispersion of Surface Tracers." Journal of Physical Oceanography 18, no. 8 (1988): 1108–23. http://dx.doi.org/10.1175/1520-0485(1988)018<1108:trolci>2.0.co;2.

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Cheong, Hin-Fatt, M. H. Abdul Khader, Chor-Juen Yang, and R. Radhakrishnan. "The dispersion of radioactive tracers along the east coast of Singapore." Coastal Engineering 17, no. 1-2 (1992): 71–92. http://dx.doi.org/10.1016/0378-3839(92)90014-l.

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Crawford, Alice. "The Use of Gaussian Mixture Models with Atmospheric Lagrangian Particle Dispersion Models for Density Estimation and Feature Identification." Atmosphere 11, no. 12 (2020): 1369. http://dx.doi.org/10.3390/atmos11121369.

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Atmospheric Lagrangian particle dispersion models, LPDM, simulate the dispersion of passive tracers in the atmosphere. At the most basic level, model output consists of the position of computational particles and the amount of mass they represent. In order to obtain concentration values, this information is then converted to a mass distribution via density estimation. To date, density estimation is performed with a nonparametric method so that output consists of gridded concentration data. Here we introduce the use of Gaussian mixture models, GMM, for density estimation. We compare to the hist

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