Principal Length Scales in Second-Order Closure Models for Canopy Turbulence

Katul, Gabriel G.; Chang, Wei-Han

doi:10.1175/1520-0450(1999)038<1631:plsiso>2.0.co;2

Cited by 72 publications

(62 citation statements)

References 36 publications

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“…One limitation to this model is that l m is assumed to be finite near the ground, which is unrealistic. However, as discussed by Katul and Chang (1999), the impact of this assumption affects a limited region, about 0.05h for dense canopies. We are well aware that a length scale specification cannot be universal across all flow regimes.…”

Section: Model For M Tmentioning

confidence: 99%

“…where Wilson and Shaw, 1977), and a 3 can be determined by the matching procedure described in Katul and Chang (1999) and which results in…”

Section: Simplifications To the K-e Models: The K-u Or One-equation Mmentioning

confidence: 99%

“…Much of the experimental set-up is described elsewhere (Katul and Albertson, 1998;Katul and Chang, 1999;Siqueira and Katul, 2002). For com- pleteness, we review the main features of the site and set-up.…”

Section: The Loblolly Pine Canopymentioning

confidence: 99%

“…Identifying the minimum turbulence closure model necessary to efficiently simulate the mean flow and measures of second-order flow statistics is a logical research question (Wilson et al, 1998). In principle, second-order closure models can predict such flow statistics (Meyers andPaw U, 1986, 1987;Meyers, 1987;Wilson, 1988;Paw and Meyers, 1989;Albertson, 1998, 1999;Ayotte et al, 1999;Katul and Chang, 1999). However, they are computationally expensive and require complex numerical algorithms for three-dimensional transport problems (especially if multiple scalar species must be treated).…”

Section: Introductionmentioning

confidence: 99%

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ONE- and TWO-Equation Models for Canopy Turbulence

Katul

Mahrt

Poggi

et al. 2004

Boundary-Layer Meteorology

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340

223

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Abstract. The predictive skills of single-and two-equation (or K-e) models to compute profiles of mean velocity (U), turbulent kinetic energy (K), and Reynolds stresses ðu 0 w 0 Þ are compared against datasets collected in eight vegetation types and in a flume experiment. These datasets range in canopy height h from 0.12 to 23 m, and range in leaf area index (LAI) from 2 to 10 m 2 m À2 . We found that for all datasets and for both closure models, measured and modelled U, K, and u 0 w 0 agree well when the mixing length (l m ) is a priori specified. In fact, the root-mean squared error between measured and modelled U, K, and u 0 w 0 is no worse than published values for second-and third-order closure approaches. Within the context of onedimensional modelling, there is no clear advantage to including a turbulent kinetic dissipation rate (e) budget when l m can be specified instead. The broader implication is that the added complexity introduced by the e budget in K-e models need not translate into improved predictive skills of U, K, and u 0 w 0 profiles when compared to single-equation models.

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Section: Model For M Tmentioning

confidence: 99%

“…where Wilson and Shaw, 1977), and a 3 can be determined by the matching procedure described in Katul and Chang (1999) and which results in…”

Section: Simplifications To the K-e Models: The K-u Or One-equation Mmentioning

confidence: 99%

Section: The Loblolly Pine Canopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

ONE- and TWO-Equation Models for Canopy Turbulence

Katul

Mahrt

Poggi

et al. 2004

Boundary-Layer Meteorology

Self Cite

340

223

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“…CC BY 4.0 License. Finnigan, 1994;Zhuang and Amiro, 1994;Raupach et al, 1996;Katul, 1998;Katul and Chang, 1999;Finnigan, 2000;Siqueira et al, 2000;Katul et al, 2004;Poggi et al, 2004b, a;Watanabe, 2004;Katul et al, 2006;Gavrilov et al, 2010Gavrilov et al, , 2011Chamecki, 2013;Katul et al, 2013;Dias-Junior et al, 2015), although recent focus in this field has shifted towards studying the effects of complex topography and heterogeneities such as edges and forest clearings. However, there are still gaps in the homogeneous canopy turbulence literature which is the motivation for this study.…”

mentioning

confidence: 99%

Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence

Banerjee

Roo

Linn

2017

Preprint

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Abstract. Studying turbulence in vegetation canopies is important in the context of a number of micrometeorological and hydrological applications. While recent focus has shifted more towards exploring different kinds of canopy heterogeneities, there are still gaps in the existing knowledge on the multiple types of dynamics involved in the case of horizontally homogeneous canopies. For example, experimental studies have indicated that turbulence in the canopy sublayer (CSL) can be divided into three regimes. In the deep-zone, the flow-field is dominated by von Kármán vortex streets and interrupted by strong sweep 5 events. The second zone near the canopy top is dominated by attached eddies and Kelvin-Helmholtz waves associated with the velocity inflection point in the mean longitudinal velocity profile. Above the canopy, the flow resembles classical boundary layer flow. In this study, these different kinds of dynamics are studied together by means of a large eddy simulation (LES).The main theme of this work is to address the question whether the parametrization of the canopy by a distributed drag force in numerical simulations instead of placing real solid obstacles is consistent with the three layer conceptual model. Unique 10 techniques such as measures from information theory and coupled oscillator analysis are used to extract the coherent structures associated with the two motions. It can be stated that a better understanding of the rich dynamics associated with the simplest case of canopy turbulence can lead to more efficient simulations and more importantly improve the interpretation of more complex scenarios.

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Coarse‐grained debris flow dynamics on erodible beds

2017

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A systematic set of flume experiments is used to investigate the features of velocity profiles within the body of coarse‐grained debris flows and the dependence of the transport sediment concentration on the relevant parameters (runoff discharge, bed slope, grain size, and form). The flows are generated in a 10 m long laboratory flume, initially filled with a layer consisting of loose debris. After saturation, a prescribed water discharge is suddenly supplied over the granular bed, and the runoff triggers a debris flow wave that reaches nearly steady conditions. Three types of material have been used in the tests: gravel with mean grain size of 3 and 5 mm, and 3 mm glass spheres. Measured parameters included: triggering water discharge, volumetric sediment discharge, sediment concentration, flow depth, and velocity profiles. The dynamic similarity with full‐sized debris flows is discussed on the basis of the relevant dimensionless parameters. Concentration data highlight the dependence on the slope angle and the importance of the quasi‐static friction angle. The effects of flow rheology on the shape of velocity profiles are analyzed with attention to the role of different stress‐generating mechanisms. A remarkable collapse of the dimensionless profiles is obtained by scaling the debris flow velocity with the runoff velocity, and a power law characterization is proposed following a heuristic approach. The shape of the profiles suggests a smooth transition between the different rheological regimes (collisional and frictional) that establish in the upper and lower regions of the flow and is compatible with the presence of multiple length scales dictated by the type of contacts (instantaneous or long lasting) between grains.

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Principal Length Scales in Second-Order Closure Models for Canopy Turbulence

Cited by 72 publications

References 36 publications

ONE- and TWO-Equation Models for Canopy Turbulence

ONE- and TWO-Equation Models for Canopy Turbulence

Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence

Coarse‐grained debris flow dynamics on erodible beds

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