Large-eddy simulation of plant canopy flows using plant-scale representation

Yue, Wusi; Parlange, Marc B.; Meneveau, Charles; Wei, Zhu; Hout, R. van; Katz, Joseph

doi:10.1007/s10546-007-9173-x

Cited by 68 publications

(53 citation statements)

References 43 publications

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“…Three specific functional forms are postulated. First, C d is a constant, an assumption used in many LES studies (e.g., Shaw and Schumann 1992;Su et al 1998;Patton et al 2003;Yue et al 2007b;Dupont and Brunet 2008;Gavrilov et al 2013). DNS results suggest that a constant instantaneous drag coefficient is a good model for rigid canopies (Santiago et al 2008).…”

Section: Approaches To Estimate the Instantaneous Drag-wind Relationshipmentioning

confidence: 99%

“…The distributed drag force depends on the leaf area density, the velocity, and the local drag coefficient. This framework has been used in a range of modelling approaches including one-dimensional first-and second-order closure (Wilson and Shaw 1977;Katul 1998;Pinard and Wilson 2001;Poggi et al 2004a;Katul et al 2011), Reynolds-averaged Navier-Stokes (RANS; Dupont et al 2006) and large-eddy simulation (LES; Shaw and Schumann 1992;Su et al 1998;Patton et al 2003;Shaw and Patton 2003;Yue et al 2007b;Dupont and Brunet 2008;Gavrilov et al 2013;Pan et al 2014a). Turbulence statistics predicted by these models are highly sensitive to the parametrization schemes employed for the local mean and instantaneous drag coefficients.…”

Section: Introductionmentioning

confidence: 99%

“…Canopy-resolving LES models using a constant drag coefficient (e.g., Shaw and Schumann 1992;Su et al 1998;Patton et al 2003;Yue et al 2007b;Dupont and Brunet 2008;Gavrilov et al 2013) can reproduce profiles of mean velocity, mean vertical momentum flux and components of turbulent kinetic energy (TKE) measured in the field. However, the skewness of streamwise and vertical velocity fluctuations are underestimated by more than 50 % with respect to the measurements.…”

Section: Introductionmentioning

confidence: 99%

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Estimating the Instantaneous Drag–Wind Relationship for a Horizontally Homogeneous Canopy

Pan

Chamecki

Nepf

2016

Boundary-Layer Meteorol

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The mean drag-wind relationship is usually investigated assuming that field data are representative of spatially-averaged metrics of statistically stationary flow within and above a horizontally homogeneous canopy. Even if these conditions are satisfied, large-eddy simulation (LES) data suggest two major issues in the analysis of observational data. Firstly, the streamwise mean pressure gradient is usually neglected in the analysis of data from terrestrial canopies, which compromises the estimates of mean canopy drag and provides misleading information for the dependence of local mean drag coefficients on local velocity scales. Secondly, no standard approach has been proposed to investigate the instantaneous drag-wind relationship, a critical component of canopy representation in LES. Here, a practical approach is proposed to fit the streamwise mean pressure gradient using observed profiles of the mean vertical momentum flux within the canopy. Inclusion of the fitted mean pressure gradient enables reliable estimates of the mean drag-wind relationship. LES data show that a local mean drag coefficient that characterizes the relationship between mean canopy drag and the velocity scale associated with total kinetic energy can be used to identify the dependence of the local instantaneous drag coefficient on instantaneous velocity. Iterative approaches are proposed to fit specific models of velocity-dependent instantaneous drag coefficients that represent the effects of viscous drag and the reconfiguration of flexible canopy elements. LES data are used to verify the assumptions and algorithms employed by these new approaches. The relationship between mean canopy drag and mean velocity, which is needed in models based on the Reynolds-averaged Navier-Stokes equations, is parametrized to account for both the dependence on velocity and the contribution from velocity variances. Finally, velocity-dependent drag coefficients lead to significant variations of the calculated displacement height and roughness length with wind speed. B Marcelo Chamecki

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Section: Approaches To Estimate the Instantaneous Drag-wind Relationshipmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Estimating the Instantaneous Drag–Wind Relationship for a Horizontally Homogeneous Canopy

Pan

Chamecki

Nepf

2016

Boundary-Layer Meteorol

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“…LES was first applied to the canopy turbulence by Shaw and Schumann (1992) and Kanda and Hino (1994) and then by many authors (Dwyer et al 1997;Shen and Leclerc 1997;Su et al 1998Su et al , 2000Patton et al 1998;Fitzmaurice et al 2004;Watanabe 2004;Yue et al 2007). All these studies showed the LES technique is an e¤ective tool for investigating the statistics, energetics and threedimensional structures of canopy turbulence.…”

Section: Introductionmentioning

confidence: 99%

LES Study on the Structure of Coherent Eddies Inducing Predominant Perturbations in Velocities in the Roughness Sublayer over Plant Canopies

Watanabe

2009

Journal of the Meteorological Society of Japan

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Large-eddy simulations (LESs) were performed for neutrally-stratified turbulent flows within and above a homogeneous plant canopy. 100 realizations of a three-dimensional turbulence field obtained from each of four LES runs, which di¤er in the driving force of the flow and the size of computational domain, were used in the present study. A conditional sampling technique was used to construct ensemble-averaged images of coherent eddies that induce predominant perturbations in the streamwise and vertical velocities near the canopy top. To reduce subjectivity, wavelet analysis was adopted for triggering the conditional sampling. Synthesis of the present study and numerous previous studies indicated that, in the canopy turbulence, the spatial scale of eddies that induce predominant perturbations in the streamwise velocity is generally three times larger than that of eddies that induce predominant perturbations in the vertical velocity, irrespective of whether concerning field observations, windtunnel experiments or numerical simulations. Therefore, scales of both eddies are mostly determined by a mechanism inherent in the roughness sublayer. An analysis of the ensemble-averaged results and each realization revealed several findings: (1) the smaller eddies that cause predominant perturbations in the vertical velocity are vortices that accord with the so-called mixing-layer (ML) analogy, which is widely accepted as a mechanism of coherent eddies developing near the canopy top; however, (2) the larger eddies inducing predominant perturbations in the streamwise velocity are not vortices and are much larger than expected from the ML analogy; (3) these eddies are streamwise-elongated motions of high-speed downdraft and low-speed updraft, having characteristic features such that the high-speed downdraft penetrates into the canopy and cross-streamwise spreads inside the canopy thus inducing low-speed updraft to the sides of the downdraft and that the low-speed updraft produces a lifted (higher than the canopy top) shear zone beneath an overriding high-speed motion thereby enhancing the shear instability in that area; (4) the high-speed and low-speed motions aligning side-by-side bear a close resemblance to streaky patterns observed in a near-surface region of planetary boundary layers, although the spatial scales are quite di¤erent.

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“…6. CI-This model was inspired by the work of (Yue et al, 2007) who advocated the use of a plant scale approach when considering canopy flows. Each tree was modelled as an individual cylinder of height and diameter equal to the height and maximum diameter of the actual tree represented, as shown in Fig.…”

Section: Representation Of the Canopy In The Cfd Modelmentioning

confidence: 99%

A study on the inclusion of forest canopy morphology data in numerical simulations for the purpose of wind resource assessment

Desmond

Watson

Aubrun

et al. 2014

Journal of Wind Engineering and Industrial Aerodynamics

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A series of numerical simulations of the flow over a forest stand have been conducted using two different turbulence closure models along with various levels of canopy morphology data. Simulations have been validated against Stereoscopic Particle Image Velocimetry measurements from a wind tunnel study using one hundred architectural model trees, the porosities of which have been assessed using a photographic technique.It has been found that an accurate assessment of the porosity of the canopy, and specifically the variability with height, improves simulation quality regardless of the turbulence closure model used or the level of canopy geometry included. The observed flow field and recovery of the wake is in line with characteristic canopy flows published in the literature and it was found that the shear stress transport turbulence model was best able to capture this detail numerically.

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Large-eddy simulation of plant canopy flows using plant-scale representation

Cited by 68 publications

References 43 publications

Estimating the Instantaneous Drag–Wind Relationship for a Horizontally Homogeneous Canopy

Estimating the Instantaneous Drag–Wind Relationship for a Horizontally Homogeneous Canopy

LES Study on the Structure of Coherent Eddies Inducing Predominant Perturbations in Velocities in the Roughness Sublayer over Plant Canopies

A study on the inclusion of forest canopy morphology data in numerical simulations for the purpose of wind resource assessment

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