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Journal articles on the topic 'Passive scalar dispersion'

Author: Grafiati

Published: 4 June 2021

Last updated: 4 February 2022

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1

Tong, Chenning, and Z. Warhaft. "Passive scalar dispersion and mixing in a turbulent jet." Journal of Fluid Mechanics 292 (June 10, 1995): 1–38. http://dx.doi.org/10.1017/s0022112095001418.

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The dispersion and mixing of passive scalar (temperature) fluctuations is studied in a turbulent jet. The temperature fluctuations were produced by heated fine wire rings placed axisymmetrically in the flow. Typically the ring diameters were of the same order as the jet, Dj, and they were placed in the self-similar region. However, other initial conditions were studied, including a very small diameter ring used to approximate a point source. Using a single ring to study dispersion (which is analogous to placing a line source in a planar flow such as grid turbulence), it was found that the inte

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2

MOLE, NILS, THOMAS P. SCHOPFLOCHER, and PAUL J. SULLIVAN. "High concentrations of a passive scalar in turbulent dispersion." Journal of Fluid Mechanics 604 (May 14, 2008): 447–74. http://dx.doi.org/10.1017/s0022112008001353.

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In problems involving the dispersion of hazardous gases in the atmosphere, the distribution of high concentrations is often of particular interest. We address the modelling of the distribution of high concentrations of a dispersing passive scalar at large Péclet number, concentrating on the case of steady releases. We argue, from the physical character of the small-scale processes, and from the statistical theory of extreme values, that the high concentrations can be fitted well by a Generalized Pareto Distribution (GPD). This is supported by evidence from a range of experiments. We show, furt

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3

BOFFETTA, G., F. DE LILLO, and A. MAZZINO. "Peripheral mixing of passive scalar at small Reynolds number." Journal of Fluid Mechanics 624 (April 10, 2009): 151–58. http://dx.doi.org/10.1017/s0022112009006004.

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Mixing of a passive scalar in the peripheral region close to a wall is investigated by means of accurate direct numerical simulations of both a three-dimensional Couette channel flow at low Reynolds numbers and a two-dimensional synthetic flow. In both cases, the resulting phenomenology can be understood in terms of the theory recently developed by Lebedev & Turitsyn (Phys. Rev. E, vol. 69, 2004, 036301). Our results prove the robustness of the identified mechanisms responsible for the persistency of scalar concentration close to the wall with important consequences in completely different

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4

Hsieh, Kun-Jung, Fue-Sang Lien, and Eugene Yee. "Numerical modeling of passive scalar dispersion in an urban canopy layer." Journal of Wind Engineering and Industrial Aerodynamics 95, no. 12 (2007): 1611–36. http://dx.doi.org/10.1016/j.jweia.2007.02.028.

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5

Philips, D. A., R. Rossi, and G. Iaccarino. "Large-eddy simulation of passive scalar dispersion in an urban-like canopy." Journal of Fluid Mechanics 723 (April 16, 2013): 404–28. http://dx.doi.org/10.1017/jfm.2013.135.

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AbstractResults from large-eddy simulations of short-range dispersion of a passive scalar from a point source release in an urban-like canopy are presented. The computational domain is that of a variable height array of buildings immersed in a pressure-driven, turbulent flow with a roughness Reynolds number ${\mathit{Re}}_{\tau } = 433$. A comparative study of several cases shows the changes in plume behaviour for different mean flow directions and source locations. The analysis of the results focuses on utilizing the high-fidelity datasets to examine the three-dimensional flow field and scala

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6

Goulart, E. V., O. Coceal, and S. E. Belcher. "Dispersion of a Passive Scalar Within and Above an Urban Street Network." Boundary-Layer Meteorology 166, no. 3 (2017): 351–66. http://dx.doi.org/10.1007/s10546-017-0315-5.

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7

Wang, Bing-Chen, Eugene Yee, and Fue-Sang Lien. "Turbulent Dispersion of a Passive Scalar in a Staggered Array of Cubes." Numerical Heat Transfer, Part B: Fundamentals 67, no. 4 (2014): 281–301. http://dx.doi.org/10.1080/10407790.2014.964531.

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8

Aguirre, Cesar, Armando B. Brizuela, Ivana Vinkovic, and Serge Simoëns. "A subgrid Lagrangian stochastic model for turbulent passive and reactive scalar dispersion." International Journal of Heat and Fluid Flow 27, no. 4 (2006): 627–35. http://dx.doi.org/10.1016/j.ijheatfluidflow.2006.02.011.

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9

Craske, John, Antoine L. R. Debugne, and Maarten van Reeuwijk. "Shear-flow dispersion in turbulent jets." Journal of Fluid Mechanics 781 (September 16, 2015): 28–51. http://dx.doi.org/10.1017/jfm.2015.417.

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We investigate the transport of a passive scalar in a fully developed turbulent axisymmetric jet at a Reynolds number of $\mathit{Re}=4815$ using data from direct numerical simulation. In particular, we simulate the response of the concentration field to an instantaneous variation of the scalar flux at the source. To analyse the time evolution of this statistically unsteady process we take an ensemble average over 16 independent simulations. We find that the evolution of $C_{m}(z,t)$, the radial integral of the ensemble-averaged concentration, is a self-similar process, with the front position

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10

Belcher, S. E., O. Coceal, E. V. Goulart, A. C. Rudd, and A. G. Robins. "Processes controlling atmospheric dispersion through city centres." Journal of Fluid Mechanics 763 (December 10, 2014): 51–81. http://dx.doi.org/10.1017/jfm.2014.661.

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AbstractWe develop a process-based model for the dispersion of a passive scalar in the turbulent flow around the buildings of a city centre. The street network model is based on dividing the airspace of the streets and intersections into boxes, within which the turbulence renders the air well mixed. Mean flow advection through the network of street and intersection boxes then mediates further lateral dispersion. At the same time turbulent mixing in the vertical detrains scalar from the streets and intersections into the turbulent boundary layer above the buildings. When the geometry is regular

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11

POPE, S. B. "The vanishing effect of molecular diffusivity on turbulent dispersion: implications for turbulent mixing and the scalar flux." Journal of Fluid Mechanics 359 (March 25, 1998): 299–312. http://dx.doi.org/10.1017/s0022112097008380.

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In 1921 G. I. Taylor introduced (with little discussion) the notion that the dispersion of a conserved passive scalar in a turbulent flow is determined by the motion of fluid particles (independent of the molecular diffusivity). Here, a hypothesis of diffusivity independence is introduced, which provides a sufficient condition for the validity of Taylor's approach. The hypothesis, which is supported by DNS data, is that, at high Reynolds number, the mean of the scalar conditional on the velocity is independent of the molecular diffusivity. From this hypothesis it is shown that (at high Reynold

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12

Xu, George, Arthur Lim, Harish Gopalan, Jing Lou, and Hee Joo Poh. "CFD Simulation of Chemical Gas Dispersion Under Atmospheric Boundary Conditions." International Journal of Computational Methods 17, no. 05 (2019): 1940011. http://dx.doi.org/10.1142/s0219876219400115.

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Pollutant control is one of the key concerns in the design of buildings, for the sake of occupational health, safety and environment sustainability. In particular, risk analyses related to emergency leakage of chemicals from storage tanks or chemical processes have aroused increasing attentions in recent days, as well as the effectiveness of mitigation measures in order to eliminate, reduce and control the risks. In this paper, a CFD methodology with nonreactive chemical gases treated as passive scalars has been developed to simulate the gas dispersion across urban environments, subject to atm

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13

VINÇONT, J. Y., S. SIMOËNS, M. AYRAULT, and J. M. WALLACE. "Passive scalar dispersion in a turbulent boundary layer from a line source at the wall and downstream of an obstacle." Journal of Fluid Mechanics 424 (November 16, 2000): 127–67. http://dx.doi.org/10.1017/s0022112000001865.

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Simultaneous measurements of the velocity and scalar concentration fields have been made in the plume emitting from a two-dimensional line source at the wall. The source is one obstacle height, h, downstream of a two-dimensional square obstacle located on the wall of a turbulent boundary layer. These measurements were made in two fluid media: water and air. In both media particle image velocimetry (PIV) was used for the velocity field measurements. For the scalar concentration measurements laser-induced uorescence (LIF) was used for the water flow and Mie scattering diffusion (MSD) for the air

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14

Haynes, P. H., and J. Vanneste. "Dispersion in the large-deviation regime. Part 1: shear flows and periodic flows." Journal of Fluid Mechanics 745 (March 19, 2014): 321–50. http://dx.doi.org/10.1017/jfm.2014.64.

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AbstractThe dispersion of a passive scalar in a fluid through the combined action of advection and molecular diffusion is often described as a diffusive process, with an effective diffusivity that is enhanced compared with the molecular value. However, this description fails to capture the tails of the scalar concentration distribution in initial-value problems. To remedy this, we develop a large-deviation theory of scalar dispersion that provides an approximation to the scalar concentration valid at much larger distances away from the centre of mass, specifically distances that are$O(t)$rathe

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15

Nottrott, Anders, Jan Kleissl, and Ralph Keeling. "Modeling passive scalar dispersion in the atmospheric boundary layer with WRF large-eddy simulation." Atmospheric Environment 82 (January 2014): 172–82. http://dx.doi.org/10.1016/j.atmosenv.2013.10.026.

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16

Hosseini, Seyed Ali, Nasser Darabiha, Dominique Thévenin, and Amir Eshghinejadfard. "Stability limits of the single relaxation-time advection–diffusion lattice Boltzmann scheme." International Journal of Modern Physics C 28, no. 12 (2017): 1750141. http://dx.doi.org/10.1142/s0129183117501418.

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In many cases, multi-species and/or thermal flows involve large discrepancies between the different diffusion coefficients involved — momentum, heat and species diffusion. In the context of classical passive scalar lattice Boltzmann (LB) simulations, the scheme is quite sensitive to such discrepancies, as relaxation coefficients of the flow and passive scalar fields are tied together through their common lattice spacing and time-step size. This in turn leads to at least one relaxation coefficient, [Formula: see text] being either very close to 0.5 or much larger than unity which, in the case o

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17

Baj, Pawel, and Oliver R. H. Buxton. "Passive scalar dispersion in the near wake of a multi-scale array of rectangular cylinders." Journal of Fluid Mechanics 864 (February 4, 2019): 181–220. http://dx.doi.org/10.1017/jfm.2019.11.

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The near wakes of flows past single- and multi-scale arrays of bars are studied by means of planar laser induced fluorescence (PLIF) and particle image velocimetry (PIV). The aim of this research is to better understand dispersion of passive scalar downstream of the multi-scale turbulence generator. In particular, the focus is on plausible manifestations of the space-scale unfolding (SSU) mechanism, which is often considered in the literature as the reason for the enhancement of the turbulent scalar flux in flows past fractal grids (i.e. specific multi-scale turbulence generators). The analysi

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18

Kaplan, H., and N. Dinar. "A stochastic model for the dispersion of a non-passive scalar in a turbulent field." Atmospheric Environment. Part A. General Topics 26, no. 13 (1992): 2413–23. http://dx.doi.org/10.1016/0960-1686(92)90371-q.

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19

Biehl, Jonathan, Bastian Paas, and Otto Klemm. "Ventilation of a Mid-Size City under Stable Boundary Layer Conditions: A Simulation Using the LES Model PALM." Atmosphere 12, no. 3 (2021): 401. http://dx.doi.org/10.3390/atmos12030401.

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City centers have to cope with an increasing amount of air pollution. The supply of fresh air is crucial yet difficult to ensure, especially under stable conditions of the atmospheric boundary layer. This case study used the PArallelized Large eddy simulation (LES) Model PALM to investigate the wind field over an urban lake that had once been built as a designated fresh air corridor for the city center of Münster, northwest, Germany. The model initialization was performed using the main wind direction and stable boundary layer conditions as input. The initial wind and temperature profiles incl

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20

LIAO, Q., and E. A. COWEN. "Relative dispersion of a scalar plume in a turbulent boundary layer." Journal of Fluid Mechanics 661 (August 2, 2010): 412–45. http://dx.doi.org/10.1017/s0022112010003058.

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The relative dispersion of a scalar plume is examined experimentally. A passive fluorescent tracer is continuously released from a flush-bed mounted source into the turbulent boundary layer of a laboratory-generated open channel flow. A two-dimensional particle image velocimetry–laser-induced florescence (PIV–LIF) technique is applied to measure the instantaneous horizontal velocity and concentration fields. Measured results are used to investigate the relationship between the boundary-layer turbulence and the evolution of the distance-neighbour function, namely the probability density distrib

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21

Foures, D. P. G., C. P. Caulfield, and P. J. Schmid. "Optimal mixing in two-dimensional plane Poiseuille flow at finite Péclet number." Journal of Fluid Mechanics 748 (April 28, 2014): 241–77. http://dx.doi.org/10.1017/jfm.2014.182.

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AbstractWe consider the nonlinear optimisation of the mixing of a passive scalar, initially arranged in two layers, in a two-dimensional plane Poiseuille flow at finite Reynolds and Péclet numbers, below the linear instability threshold. We use a nonlinear-adjoint-looping approach to identify optimal perturbations leading to maximum time-averaged energy as well as maximum mixing in a freely evolving flow, measured through the minimisation of either the passive scalar variance or the so-called mix-norm, as defined by Mathew, Mezić & Petzold (Physica D, vol. 211, 2005, pp. 23–46). We show th

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22

Brosten, Tyler R. "Short-time asymptotics of hydrodynamic dispersion in porous media." Journal of Fluid Mechanics 732 (September 17, 2013): 687–705. http://dx.doi.org/10.1017/jfm.2013.429.

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AbstractWe consider convection–diffusion transport of a passive scalar within porous media having a piecewise-smooth and reflecting pore–grain interface. The corresponding short-time expansion of molecular displacement time-correlation functions is determined for the generalized steady convection field. By interpreting the generalized short-time expansion of dispersion dynamics in the context of low-Reynolds-number flow through macroscopically homogeneous porous media, we demonstrate the connection between hydrodynamic permeability and short-time dynamics. The analytical short-time expansion i

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23

Wang, Qi, Yosuke Hasegawa, and Tamer A. Zaki. "Spatial reconstruction of steady scalar sources from remote measurements in turbulent flow." Journal of Fluid Mechanics 870 (May 14, 2019): 316–52. http://dx.doi.org/10.1017/jfm.2019.241.

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Identifying the source of passive scalar transported in a turbulent environment from remote measurements is an ill-posed problem due to the irreversibility of diffusive processes. A significant difficulty of the source reconstruction is due to different potential source locations generating very highly correlated signals at the sensor. A variational algorithm is formulated, which utilizes high-fidelity simulations to reconstruct the spatial distribution of the source. A cost functional is defined based on the difference between the true measurements and their prediction from the simulations wi

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24

Loisy, Aurore, Aurore Naso, and Peter D. M. Spelt. "The effective diffusivity of ordered and freely evolving bubbly suspensions." Journal of Fluid Mechanics 840 (February 9, 2018): 215–37. http://dx.doi.org/10.1017/jfm.2018.84.

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We investigate the dispersion of a passive scalar such as the concentration of a chemical species, or temperature, in homogeneous bubbly suspensions, by determining an effective diffusivity tensor. Defining the longitudinal and transverse components of this tensor with respect to the direction of averaged bubble rise velocity in a zero mixture velocity frame of reference, we focus on the convective contribution thereof, this being expected to be dominant in commonly encountered bubbly flows. We first extend the theory of Kochet al.(J. Fluid Mech., vol. 200, 1989, pp. 173–188) (which is for dis

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25

Buaria, D., P. K. Yeung, and B. L. Sawford. "A Lagrangian study of turbulent mixing: forward and backward dispersion of molecular trajectories in isotropic turbulence." Journal of Fluid Mechanics 799 (June 23, 2016): 352–82. http://dx.doi.org/10.1017/jfm.2016.359.

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Statistics of the trajectories of molecules diffusing via Brownian motion in a turbulent flow are extracted from simulations of stationary isotropic turbulence, using a postprocessing approach applicable in both forward and backward reference frames. Detailed results are obtained for Schmidt numbers ($Sc$) from 0.001 to 1000 at Taylor-scale Reynolds numbers up to 1000. The statistics of displacements of single molecules compare well with the earlier theoretical work of Saffman (J. Fluid Mech. vol. 8, 1960, pp. 273–283) except for the scaling of the integral time scale of the fluid velocity fol

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26

Stefanello, M. B., G. A. Degrazia, L. Mortarini, et al. "Development of an analytical Lagrangian model for passive scalar dispersion in low-wind speed meandering conditions." Physica A: Statistical Mechanics and its Applications 492 (February 2018): 1007–15. http://dx.doi.org/10.1016/j.physa.2017.11.031.

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27

Marro, Massimo, Chiara Nironi, Pietro Salizzoni, and Lionel Soulhac. "Dispersion of a Passive Scalar Fluctuating Plume in a Turbulent Boundary Layer. Part II: Analytical Modelling." Boundary-Layer Meteorology 156, no. 3 (2015): 447–69. http://dx.doi.org/10.1007/s10546-015-0041-9.

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28

Marro, Massimo, Pietro Salizzoni, Lionel Soulhac, and Massimo Cassiani. "Dispersion of a Passive Scalar Fluctuating Plume in a Turbulent Boundary Layer. Part III: Stochastic Modelling." Boundary-Layer Meteorology 167, no. 3 (2018): 349–69. http://dx.doi.org/10.1007/s10546-017-0330-6.

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29

VINKOVIC, IVANA, CESAR AGUIRRE, and SERGE SIMOËNS. "Large-eddy simulation and Lagrangian stochastic modeling of passive scalar dispersion in a turbulent boundary layer." Journal of Turbulence 7 (January 2006): N30. http://dx.doi.org/10.1080/14685240600595537.

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30

Gavrilov, K., D. Morvan, G. Accary, D. Lyubimov, and S. Meradji. "Numerical simulation of coherent turbulent structures and of passive scalar dispersion in a canopy sub-layer." Computers & Fluids 78 (April 2013): 54–62. http://dx.doi.org/10.1016/j.compfluid.2012.08.021.

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31

Salizzoni, P., R. Van Liefferinge, L. Soulhac, P. Mejean, and R. J. Perkins. "Influence of wall roughness on the dispersion of a passive scalar in a turbulent boundary layer." Atmospheric Environment 43, no. 3 (2009): 734–48. http://dx.doi.org/10.1016/j.atmosenv.2008.07.057.

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32

LEPORE, J., and L. MYDLARSKI. "Lateral dispersion from a concentrated line source in turbulent channel flow." Journal of Fluid Mechanics 678 (May 3, 2011): 417–50. http://dx.doi.org/10.1017/jfm.2011.119.

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The dispersion of a passive scalar (temperature) from a concentrated line source in fully developed, high-aspect-ratio turbulent channel flow is studied herein. The line source is oriented in the direction of the inhomogeneity of the velocity field, resulting in a thermal plume that is statistically three-dimensional. This configuration is selected to investigate the lateral dispersion of a passive scalar in an inhomogeneous turbulent flow (i.e. dispersion in planes parallel to the channel walls). Measurements are recorded at six wall-normal distances (y/h = 0.10, 0.17, 0.33, 0.50, 0.67 and 1.

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33

Özdemir, İ. B., J. H. Whitelaw, and A. F. Biçen. "Flow Properties and Passive Scalar Transport in a Model Room With Relevance to Ventilation Efficiency." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 210, no. 4 (1996): 297–307. http://dx.doi.org/10.1243/pime_proc_1996_210_202_02.

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This paper describes an experimental investigation of air flow patterns and related passive scalar transport inside a model room with emphasis on the statistical time-scales of the dispersion process and the local ventilation effectiveness. Time-averaged and instantaneous structures of the turbulent flow were examined by local measurements inside a negatively pressurized cubic enclosure of 2 m side dimension and ventilated through single-supply and exhaust registers at an extract flowrate of 1.81 m3/min with a corresponding air change of 13.6 per hour. Sulphur hexafluoride was introduced at th

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34

Rossi, R., and G. Iaccarino. "Numerical analysis and modeling of plume meandering in passive scalar dispersion downstream of a wall-mounted cube." International Journal of Heat and Fluid Flow 43 (October 2013): 137–48. http://dx.doi.org/10.1016/j.ijheatfluidflow.2013.04.006.

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35

Cai, Xiaoming. "Effects of differential wall heating in street canyons on dispersion and ventilation characteristics of a passive scalar." Atmospheric Environment 51 (May 2012): 268–77. http://dx.doi.org/10.1016/j.atmosenv.2012.01.010.

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36

Park, Seung-Bu, Jong-Jin Baik, Siegfried Raasch, and Marcus Oliver Letzel. "A Large-Eddy Simulation Study of Thermal Effects on Turbulent Flow and Dispersion in and above a Street Canyon." Journal of Applied Meteorology and Climatology 51, no. 5 (2012): 829–41. http://dx.doi.org/10.1175/jamc-d-11-0180.1.

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AbstractThermal effects on turbulent flow and dispersion in and above an idealized street canyon with a street aspect ratio of 1 are numerically investigated using the parallelized large-eddy simulation model (“PALM”). Each of upwind building wall, street bottom, and downwind building wall is heated, and passive scalars are emitted from the street bottom. When compared with the neutral (no heating) case, the heating of the upwind building wall or street bottom strengthens a primary vortex in the street canyon and the heating of the downwind building wall induces a shrunken primary vortex and a

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37

VILLERMAUX, EMMANUEL, and CLAUDIA INNOCENTI. "On the geometry of turbulent mixing." Journal of Fluid Mechanics 393 (August 25, 1999): 123–47. http://dx.doi.org/10.1017/s0022112099005674.

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We investigate the temporal evolution of the geometrical distribution of a passive scalar injected continuously into the far field of a turbulent water jet at a scale d smaller than the local integral scale of the turbulence. The concentration field is studied quantitatively by a laser-induced- fluorescence technique on a plane cut containing the jet axis. Global features such as the scalar dispersion from the source, as well as the fine structure of the scalar field, are analysed. In particular, we define the volume occupied by the regions whose concentration is larger than a given concentrat

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Jiang, Jianbo, and Xinlei Wang. "On the Numerical Study of Indoor Particle Dispersion and Spatial Distribution." Air, Soil and Water Research 5 (January 2012): ASWR.S8113. http://dx.doi.org/10.4137/aswr.s8113.

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In this paper, particle dispersion and spatial distribution in a full scale (5.5 m x 2.4 m x 3.7 m) forced ventilated room are investigated using four different multiphase flow models, including passive scalar model, discrete particle phase model, mixture model and Eulerian model. The main differences between these four models lie in how the particles are modeled. A two layer k-∊ turbulence model is used to calculate airflows. Simulated airflow characteristics and particle concentration are compared with corresponding experimental data. The results show that only discrete particle phase model

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39

Nironi, Chiara, Pietro Salizzoni, Massimo Marro, Patrick Mejean, Nathalie Grosjean, and Lionel Soulhac. "Dispersion of a Passive Scalar Fluctuating Plume in a Turbulent Boundary Layer. Part I: Velocity and Concentration Measurements." Boundary-Layer Meteorology 156, no. 3 (2015): 415–46. http://dx.doi.org/10.1007/s10546-015-0040-x.

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40

Le Ribault, C., S. Simoëns, and I. Vinkovic. "HYBRID LARGE EDDY SIMULATION/LAGRANGIAN STOCHASTIC MODEL FOR TURBULENT PASSIVE AND REACTIVE SCALAR DISPERSION IN A PLANE JET." Chemical Engineering Communications 199, no. 4 (2012): 435–60. http://dx.doi.org/10.1080/00986445.2011.591216.

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41

Glazunov, Andrey, Üllar Rannik, Victor Stepanenko, et al. "Large-eddy simulation and stochastic modeling of Lagrangian particles for footprint determination in the stable boundary layer." Geoscientific Model Development 9, no. 9 (2016): 2925–49. http://dx.doi.org/10.5194/gmd-9-2925-2016.

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Abstract. Large-eddy simulation (LES) and Lagrangian stochastic modeling of passive particle dispersion were applied to the scalar flux footprint determination in the stable atmospheric boundary layer. The sensitivity of the LES results to the spatial resolution and to the parameterizations of small-scale turbulence was investigated. It was shown that the resolved and partially resolved (“subfilter-scale”) eddies are mainly responsible for particle dispersion in LES, implying that substantial improvement may be achieved by using recovering of small-scale velocity fluctuations. In LES with the

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42

Branford, S., O. Coceal, T. G. Thomas, and S. E. Belcher. "Dispersion of a Point-Source Release of a Passive Scalar Through an Urban-Like Array for Different Wind Directions." Boundary-Layer Meteorology 139, no. 3 (2011): 367–94. http://dx.doi.org/10.1007/s10546-011-9589-1.

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43

Elfverson, Daniel, and Christian Lejon. "Use and Scalability of OpenFOAM for Wind Fields and Pollution Dispersion with Building- and Ground-Resolving Topography." Atmosphere 12, no. 9 (2021): 1124. http://dx.doi.org/10.3390/atmos12091124.

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Complex flow and pollutant dispersion simulations in real urban settings were investigated by using computational fluid dynamics (CFD) simulations with the SST k−ω Reynolds-averaged Navier–Stokes (RANS) equation with OpenFOAM. The model was validated with a wind-tunnel experiment using two surface-mounted cubes in tandem, and the flow features were reproduced with the correct qualitative behaviour. The real urban geometry of the Parade Square in Warsaw, Poland was represented with both laser-scanning data for the ground geometry and the CityGML standard to describe the buildings as an example.

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44

KROCHAK, PAUL, and LARS THOMSSON. "A new method for characterizing turbulent mixing in semiconcentrated suspensions." November 2011 11, no. 11 (2011): 45–52. http://dx.doi.org/10.32964/tj10.11.45.

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A high-frequency conductivity probe was used in conjunction with advanced signal processing to measure the turbulent fluctuations of a passive scalar, namely a saline solution, injected into semiconcentrated, monodispersed suspensions consisting of either 2-mm rayon fibers or 130-μm microspheres. The probe was mounted in a pipe flow so that its radial position could be adjusted manually. A saline solution was injected into the centerline of the pipe at a specified velocity relative to the suspension flow. The mean conductivity signal gathered with this tool enabled estimation of the local conc

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45

KANEDA, YUKIO, and TAKAKI ISHIDA. "Suppression of vertical diffusion in strongly stratified turbulence." Journal of Fluid Mechanics 402 (January 10, 2000): 311–27. http://dx.doi.org/10.1017/s0022112099007041.

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A spectral approximation for diffusion of passive scalar in stably and strongly stratified turbulence is presented. The approximation is based on a linearized approximation for the Eulerian two-time correlation and Corrsin's conjecture for the Lagrangian two-time correlation. For strongly stratified turbulence, the vertical component of the turbulent velocity field is well approximated by a collection of Fourier modes (waves) each of which oscillates with a frequency depending on the direction of the wavevector. The proposed approximation suggests that the phase mixing among the Fourier modes

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Zhou, Bowen, Kefeng Zhu, and Ming Xue. "A Physically Based Horizontal Subgrid-Scale Turbulent Mixing Parameterization for the Convective Boundary Layer." Journal of the Atmospheric Sciences 74, no. 8 (2017): 2657–74. http://dx.doi.org/10.1175/jas-d-16-0324.1.

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Abstract Compared to the representation of vertical turbulent mixing through various planetary boundary layer (PBL) schemes, the treatment of horizontal turbulent mixing in the boundary layer has received much less attention. In mesoscale and convective-scale models, subgrid-scale horizontal turbulent mixing has traditionally been associated with mesoscale circulations or eddies. Its parameterization most often adopts the gradient-diffusion model, where the horizontal mixing coefficients are usually set constant, or through the 2D Smagorinsky formulation, or in some cases based on the 1.5-orde

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Tavangar, Tooran, Hesam Tofighian, and Ali Tarokh. "Investigation of the Horizontal Motion of Particle-Laden Jets." Computation 8, no. 2 (2020): 23. http://dx.doi.org/10.3390/computation8020023.

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Particle-laden jet flows can be observed in many industrial applications. In this investigation, the horizontal motion of particle laden jets is simulated using the Eulerian–Lagrangian framework. The two-way coupling is applied to the model to simulate the interaction between discrete and continuum phase. In order to track the continuum phase, a passive scalar equation is added to the solver. Eddy Life Time (ELT) is employed as a dispersion model. The influences of different non-dimensional parameters, such as Stokes number, Jet Reynolds number and mass loading ratio on the flow characteristic

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Cassiani, M., A. Stohl, and S. Eckhardt. "The dispersion characteristics of air pollution from world's megacities." Atmospheric Chemistry and Physics Discussions 12, no. 10 (2012): 26351–400. http://dx.doi.org/10.5194/acpd-12-26351-2012.

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Abstract. Megacities are extreme examples of the continuously growing urbanization of human population that pose (new) challenges to the environment and human health at a local scale. However, because of their size megacities also have larger-scale effects and more research is needed to quantify their regional and global scale impacts. We performed a study of the characteristics of plumes dispersing from a group of thirty-six of world's megacities using the Lagrangian particle model FLEXPART and focusing on black carbon (BC) emissions during the years 2003–2005. BC was selected since it is rep

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Cassiani, M., A. Stohl, and S. Eckhardt. "The dispersion characteristics of air pollution from the world's megacities." Atmospheric Chemistry and Physics 13, no. 19 (2013): 9975–96. http://dx.doi.org/10.5194/acp-13-9975-2013.

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Abstract. Megacities are extreme examples of the continuously growing urbanization of the human population that pose (new) challenges to the environment and human health at a local scale. However, because of their size megacities also have larger-scale effects, and more research is needed to quantify their regional- and global-scale impacts. We performed a study of the characteristics of pollution plumes dispersing from a group of 36 of the world's megacities using the Lagrangian particle model FLEXPART and focusing on black carbon (BC) emissions during the years 2003–2005. BC was selected sin

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Lee, Gwang-Jin, Domingo Muñoz-Esparza, Chaeyeon Yi, and Hi Jun Choe. "Application of the Cell Perturbation Method to Large-Eddy Simulations of a Real Urban Area." Journal of Applied Meteorology and Climatology 58, no. 5 (2019): 1125–39. http://dx.doi.org/10.1175/jamc-d-18-0185.1.

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AbstractWith the continuous increase in computing capabilities, large-eddy simulation (LES) has recently gained popularity in applications related to flow, turbulence, and dispersion in the urban atmospheric boundary layer (ABL). Herein, we perform high-resolution building-scale LES over the Seoul, South Korea, city area to investigate the impact of inflow turbulence on the resulting turbulent flow field in the urban ABL. To that end, LES using the cell perturbation method for inflow turbulence generation is compared to a case where no turbulence fluctuations in the incoming ABL are present (u

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