A wind tunnel study of turbulent dispersion over two- and three-dimensional gentle hills from upwind point sources in neutral flow

Gong, Wanmin

doi:10.1007/bf00183954

Cited by 17 publications

(6 citation statements)

References 9 publications

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“…The stochastic Lagrangian one-particle method enables simulations without much computational cost and with good results. The results of the numerical simulation using the ARPS code (LES-STO) of the concentrations of CO 2 emitted by a chimney up wind uphill are in good agreement with experimental measurements performed in a wind tunnel [13].…”

Section: Discussionsupporting

confidence: 76%

“…This chapter describes the assumptions and theoretical considerations of the coupling between these STO models with LES. Next, simulation results are compared with CO 2 measurements emitted from an upwind source made by Gong [13]. Finally, model results are compared with measurements of copper concentration made by Fernández-Turiel [14] in Lastenia town, province of Tucuman, Argentina, caused by pollution from a smelter during a severe wind event.…”

Section: Introductionmentioning

confidence: 99%

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Computational Tools for the Simulation of Atmospheric Pollution Transport During a Severe Wind Event in Argentina

Aguirre¹,

Brizuela²

2016

Atmospheric Hazards - Case Studies in Modeling, Communication, and Societal Impacts

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This chapter details the theoretical aspects of numerical methods for the simulation of atmospheric phenomena, such as severe thunderstorms and turbulent transport of the dangerous gases and solid particles into the atmospheric boundary layer. Numerical methods are included in computational algorithms to solve large turbulent scales using large eddy simulation (LES) techniques to obtain acceptable results of turbulent flows. However, microphysics processes involving evaporation, condensation and precipitation water using LES techniques are parameterized. These atmospheric processes are simulated using the advanced regional prediction systems (ARPS) code. On the contrary, atmospheric transport of pollutants is simulated using ARPS code coupled with a Lagrangian stochastic one-particle method. The theoretical details of this coupling are presented. Later, we show some laboratory experiments of plume dispersion emitted from gaseous sources, and the results of the computational simulation tool are compared after obtaining good agreement of the gas concentrations on the stream-wise vertical plane and over the ground. Finally, we present a simulation of a pollution event of copper solid particles at San Miguel de Tucumán city, Argentina. The geographical distributions of copper particle concentrations are in good agreement with the measurements carried out experimentally.

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Section: Discussionsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Computational Tools for the Simulation of Atmospheric Pollution Transport During a Severe Wind Event in Argentina

Aguirre¹,

Brizuela²

2016

Atmospheric Hazards - Case Studies in Modeling, Communication, and Societal Impacts

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“…Ruck and Adams, 1991); 2. wind energy monitoring (identification of potential location of wind turbines; see Ayotte, Davy and Coppin, 2001;Finnigan and Belcher, 2004); 3. forest-atmosphere scalar exchange of pollutant, pollen, greenhouse gases, energy or momentum (identification of dispersion characteristics and better interpretation of micrometeorological measurements in areas submitted to topographic influences; e.g. Gong, 1991;Raupach and Finnigan, 1997;Katul et al, 2006); 4. forest fire propagation (Kobayashi, Pereira and Siqueria, 1994).…”

Section: Introductionmentioning

confidence: 99%

Large‐eddy simulation of turbulent flow over a forested hill: Validation and coherent structure identification

Dupont¹,

Brunet²,

Finnigan

2008

Quart J Royal Meteoro Soc

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ABSTRACT:Modelling turbulent flow at a very fine scale within and above vegetation canopies over complex terrain is of great interest for many environmental applications. Over the last decade, it has been demonstrated that the large-eddy simulation (LES) technique is able to reproduce in detail many observed features of turbulent flow over homogeneous and heterogeneous vegetation canopies on flat terrain. For the first time, a nested LES of turbulent flow within and above a forested canopy on an isolated two-dimensional hill is analysed and validated against pressure and velocity data from a wind-tunnel experiment. The model is shown to be able to reproduce accurately the main features observed over a forested hill. The results also confirm recent observations on the intermittency of the recirculation region behind the hill, and on the domination of sweep motions in momentum transfer at the canopy top all along the hill. The main characteristics of turbulent structures have also been investigated from the analysis of vorticity fields and two-point velocity correlations across the hill. It is shown that the streamwise wind velocity upwind from the summit is not correlated with the flow within the wake region but only with the flow above it, while in the wake region the streamwise wind velocity at the canopy top is only correlated with the flow within the wake region. This result suggests that turbulence within the wake region results from the superposition of various turbulent structures: large turbulent structures induced by the elevated shear layer that may result from the rolling over of Kelvin-Helmotz instabilities, structures induced at the lee-side foot of the hill by an adverse pressure gradient and structures induced by the presence of the canopy. Implications of hilly terrain on canopy-atmosphere exchanges and tree vulnerability to windload are briefly discussed.

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“…3 the present geometry lies in a range of the parameters a and b which is common in flows over low hills (Boyer and Davies 2000). Gong and Ibbetson (1989) and Gong (1991) used b % 0.1 in their wind tunnel study of flow over hills. The flow over a wavy bottom surface-the top surface either rigid or a free surface-has been used as a model for geophysical flows.…”

Section: Introductionmentioning

confidence: 99%

Scalar transport from a point source in flows over wavy walls

2007

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Simultaneous measurements of the velocity and concentration field in fully developed turbulent flows over a wavy wall are described. The concentration field originates from a low-momentum plume of a passive tracer. PLIF and digital particle image velocimetry are used to make spatially resolved measurements of the structure of the scalar distribution and the velocity. The measurements are performed at three different Reynolds numbers of Re b = 5,600, Re b = 11,200 and Re b = 22,400, respectively, based on the bulk velocity u b and the total channel height 2h. The velocity field and the scalar field are investigated in a water channel with an aspect ratio of 12:1, where the bottom wall of the test section consists of a train of sinusoidal waves. The wavy wall is characterized by the amplitude to wavelength ratio a = 0.05 and the ratio b between the wave amplitude and the half channel height where b = 0.1. The scalar is released from a point source at the wave crest. For the concentration measurements, Rhodamine B is used as tracer dye. At low to moderate Reynolds number, the flow field is characterized through a recirculation zone which develops after the wave crest. The recirculation zone induces high intensities of the fluctuations of the streamwise velocity and wall-normal velocity. Furthermore, large-scale structures are apparent in the flow field. In previous investigations it has been shown that these largescale structures meander laterally in flows over wavy bottom walls. The investigations show a strong effect of the wavy bottom wall on the scalar mixing. In the vicinity of the source, the scalar is transported by packets of fluid with a high scalar concentration. As they move downstream, these packets disintegrate into filament-like structures which are subject to strong gradients between the filaments and the surrounding fluid. The lateral scale of the turbulent plume is smaller than the lateral scale of the large-scale structures in the flow field and the plume dispersion is dominated by the structures in the flow field. Due to the lateral meandering of the large-scale structures of the flow field, also the scalar plume meanders laterally. Compared to turbulent plumes in plane channel flows, the wavy bottom wall enhances the mixing effect of the turbulent flow and the spreading rate of the scalar plume is increased.

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A wind tunnel study of turbulent dispersion over two- and three-dimensional gentle hills from upwind point sources in neutral flow

Cited by 17 publications

References 9 publications

Computational Tools for the Simulation of Atmospheric Pollution Transport During a Severe Wind Event in Argentina

Computational Tools for the Simulation of Atmospheric Pollution Transport During a Severe Wind Event in Argentina

Large‐eddy simulation of turbulent flow over a forested hill: Validation and coherent structure identification

Scalar transport from a point source in flows over wavy walls

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