Flow through porous fences in thick boundary layers: comparisons between laboratory and numerical experiments

Packwood, A.

doi:10.1016/s0167-6105(00)00025-8

Cited by 66 publications

(39 citation statements)

References 9 publications

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“…Hence herein we are going to focus the discussion on RNG and realizable k-e. From Figs. 3-8, we can observe that the RNG and realizable k-e turbulence models seem to have better performance for large porosities (f X 0.35), especially in the far lee field x/hbX4 and no great discrepancies are found between them. Most of the differences in the value of peak velocity ratio can be attributed to the computation of turbulent kinetic energy because mean velocity is well estimated as presented in Section 3 and as found by Packwood (2000). For these cases, it has been checked (not shown in this paper) that RNG k-e produces lower values of turbulent kinetic energy than realizable k-e, explaining the lower value of peak velocity ratio that is generally found.…”

Section: Evaluation Of Turbulence Models and Parameters Usedsupporting

confidence: 51%

“…Some studies compare independently average and turbulent components (e.g. Packwood, 2000 found better results in numerical simulations for mean velocity than for turbulence parameters). However, in this work we intend to summarize the information of the shelter zone created in just one parameter defined as the peak velocity ratio:…”

Section: Evaluation Of Turbulence Models and Parameters Usedmentioning

confidence: 99%

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Experimental and numerical study of wind flow behind windbreaks

Santiago

Martín

Cuerva

et al. 2007

Atmospheric Environment

109

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Experimental and numerical study of wind flow behind windbreaks AbstractThe shelter effect of a windbreak protects aggregate piles and provides a reduction of particle emissions in harbours. RANS (Reynolds-averaged Navier-Stokes equations) simulations using three variants of k-e (standard k-e, RNG k-e and realizable k-e) turbulence closure models have been performed to analyse wind flow characteristics behind an isolated fence located on a flat surface without roughness elements. The performance of the three turbulence models has been assessed by wind tunnel experiments. Cases of fences with different porosities (f ) have been evaluated using wind tunnel experiments as well as numerical simulations. The aim is to determine an optimum porosity for sheltering effect of an isolated windbreak. A value of 0.35 was found as the optimum value among the studied porosities (f = 0, 0.1, 0.24, 0.35, 0.4, 0.5).

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Section: Evaluation Of Turbulence Models and Parameters Usedsupporting

confidence: 51%

Section: Evaluation Of Turbulence Models and Parameters Usedmentioning

confidence: 99%

Experimental and numerical study of wind flow behind windbreaks

Santiago

Martín

Cuerva

et al. 2007

Atmospheric Environment

109

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“…The momentum equation is given by: where t is time, p is the mean pressure, u i u j are the Reynolds stresses and S i is a source term that is zero everywhere except inside the canopy. The k-ε turbulence closure model (k is it turbulent kinetic energy and ε is its dissipation rate) or one of its variants was employed in the majority of previous studies of flow through windbreaks (e.g., Wilson and Mooney 1997;Packwood 2000;Santiago et al 2007) and for 3-D fences (Lin 2006;Li et al 2007;Bourdin and Wilson 2008) yielding reasonable agreement with experimental results. Therefore it was adopted in the present study.…”

Section: The Governing Equationsmentioning

confidence: 99%

“…Gross (1987) computed the pressure distribution around a single tree. Hagen et al (1981) as well as Wilson (1985), Wang and Takle (1995), Packwood (2000), Wang et al (2001), Wilson and Yee (2003), Santiago et al (2007) investigated, using a k-ε turbulence model, the effect of width, height, porosity and other parameters related to two-dimensional (2-D) fences. Bourdin and Wilson (2008) compared 2-D simulations of windbreaks and three-dimensional (3-D) simulations of homogeneous shelterbelts with experimental data, demonstrating good agreement.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Airflow Across Trees in a Windbreak

Rosenfeld

Marom

Bitan

2010

Boundary-Layer Meteorol

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The flow across a three-dimensional (3-D) windbreak comprising individual cypress trees is studied to establish the significance and extent of the 3-D flow patterns. The cypress tree is modelled as a solid cylindrical stem and a conic porous canopy. Cases with a single row of trees or two rows of trees with different distances between the rows are considered; in the case of a single row, several densities of the canopy are used. The steady Reynoldsaveraged Navier-Stokes (RANS) approximation is solved using a commercial computational fluid dynamics (CFD) package and a high-resolution mesh. Three-dimensional flow is found in the vicinity of the windbreak up to a leeward distance of 1-2 tree-heights, depending on the density of the canopy, and is manifest as significant lateral variations and reduced vertical flow. At larger leeward distances, a two-dimensional (2-D) flow is established with characteristics similar to existing 2-D studies; the flow leeward of the last row is insensitive to the distance between the rows. Homogeneous 2-D windbreak models are found to be inaccurate in the vicinity of the windbreak. This is exactly the region that needs to be sheltered in many cases, since the inner vegetation is anyway protected by the outer vegetation.

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“…The sand velocity profiles, which is an important aspect of sediment transport both in air and ocean, have been investigated by researchers through experiment [4][5][6][7] and the numerical simulation [13,14]. Most previous numerical studies [15,16] on porous fences excluded the presence of the sand grains and concentrated on wind velocity deficit of the wake behind the fences. In this paper, we focus on the shelter effect of particle velocity as the sand acts more directly than the wind in sand transportation control.…”

mentioning

confidence: 99%

A lattice Boltzmann-Saltation model and its simulation of aeolian saltation at porous fences

Shi

2014

Theor. Comput. Fluid Dyn.

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This paper introduces a 2D lattice Boltzmann-Saltation (LBM-Saltation) model for numerical simulation of velocity profiles of windblown sand particles. The model is based on the LBM equations for transient, incompressible viscous flow. We first introduced a lattice Boltzmann subgrid model, which was used to predict the turbulent wind field. Two-way coupling was then used to describe the interaction between wind and the saltating sand particles. The correctness of the model was verified by comparing the simulated results of several important variables of wind-sand flow with that of experiment over a flat bed surface. To show the feasibility of this model with complex boundary conditions, we used it to simulate the wind-sand flow at porous wind fences and mainly discussed the particle velocity profiles. Single porous wind fence case was computed first and compared with the measurement. Two tandem porous wind fences cases were simulated next. Different distance and porosity of the fences were considered to quantitatively investigate the variation of the shelter effect. The simulated results achieved additional conclusions: The wind speed and the velocity of sand particles are obviously weakened because of the fence; reduction of the particle velocity by porous fence varies with the fence distance and porosity; the larger the distance or the porosity (significantly larger than the 0.3), the worse the shelter effect, and the weaker the reduction of particle velocity.

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Flow through porous fences in thick boundary layers: comparisons between laboratory and numerical experiments

Cited by 66 publications

References 9 publications

Experimental and numerical study of wind flow behind windbreaks

Experimental and numerical study of wind flow behind windbreaks

Numerical Simulation of the Airflow Across Trees in a Windbreak

A lattice Boltzmann-Saltation model and its simulation of aeolian saltation at porous fences

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