ONE- and TWO-Equation Models for Canopy Turbulence

Katul, Gabriel G.; Mahrt, L.; Poggi, Davide; Sanz, Christophe

doi:10.1023/b:boun.0000037333.48760.e5

Cited by 344 publications

(263 citation statements)

References 65 publications

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“…For reference, K-ε model results described in Katul et al (36) are also shown in Figure 1. Both the analytical and K-ε models captured the variations well in wind speed profiles measured by Wilson (39), with coefficient of determination (r 2 ) values of 0.987 and 0.989, respectively.…”

Section: Wind Profilesmentioning

confidence: 99%

Estimation of In-Canopy Ammonia Sources and Sinks in a Fertilized Zea mays Field

Bash

Walker

Katul

et al. 2010

Environ. Sci. Technol.

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An analytical model was developed to describe in-canopy vertical distribution of ammonia (NH 3 ) sources and sinks and vertical fluxes in a fertilized agricultural setting using measured in-canopy mean NH 3 concentration and wind speed profiles. This model was applied to quantify in-canopy air-surface exchange rates and above-canopy NH 3 fluxes in a fertilized corn (Zea mays) field. Modeled air-canopy NH 3 fluxes agreed well with independent above-canopy flux estimates. Based on the model results, the urea fertilized soil surface was a consistent source of NH 3 one month following the fertilizer application, whereas the vegetation canopy was typically a net NH 3 sink with the lower portion of the canopy being a constant sink. The model results suggested that the canopy was a sink for some 70% of the estimated soil NH 3 emissions. A logical conclusion is that parametrization of within-canopy processes in air quality models are necessary to explore the impact of agricultural field level management practices on regional air quality. Moreover, there are agronomic and environmental benefits to timing liquid fertilizer applications as close to canopy closure as possible. Finally, given the large withincanopy mean NH 3 concentration gradients in such agricultural settings, a discussion about the suitability of the proposed model is also presented.

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Section: Wind Profilesmentioning

confidence: 99%

Estimation of In-Canopy Ammonia Sources and Sinks in a Fertilized Zea mays Field

Bash

Walker

Katul

et al. 2010

Environ. Sci. Technol.

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“…The problem is further complicated over forests since the forest applies a significant drag to the incoming flow, providing a spectral shortcut in the energy transfer between large and small scales of motion (Baldocchi and Hutchison 1988;Finnigan 2000). Svensson and Häggkvist (1990) and Katul et al (2004) suggested modifying the standard k − model equations for k and (namely the turbulent kinetic energy and the rate of turbulent kinetic energy dissipation, respectively) to account for such mechanisms. Silva Lopes et al (2013) provided expressions for the additional terms in the k − equations, validating them for several flow cases with different complexities.…”

Section: Introductionmentioning

confidence: 99%

A Linearized $$k-\epsilon $$ k - ϵ Model of Forest Canopies and Clearings

Segalini

Nakamura

Fukagata

2016

Boundary-Layer Meteorol

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A linearized analysis of the Reynolds-averaged Navier-Stokes (RANS) equations is proposed where the k − turbulence model is used. The flow near the forest is obtained as the superposition of the undisturbed incoming boundary layer plus a velocity perturbation due to the forest presence, similar to the approach proposed by Belcher et al. (J Fluid Mech 488:369-398, 2003). The linearized model has been compared against several non-linear RANS simulations with many leaf-area index values and large-eddy simulations using two different values of leaf-area index. All the simulations have been performed for a homogeneous forest and for four different clearing configurations. Despite the model approximations, the mean velocity and the Reynolds stress u w have been reasonably reproduced by the firstorder model, providing insight about how the clearing perturbs the boundary layer over forested areas. However, significant departures from the linear predictions are observed in the turbulent kinetic energy and velocity variances. A second-order correction, which partly accounts for some non-linearities, is therefore proposed to improve the estimate of the turbulent kinetic energy and velocity variances. The results suggest that only a region close to the canopy top is significantly affected by the forest drag and dominated by the non-linearities, while above three canopy heights from the ground only small effects are visible and both the linearized model and the simulations have the same trends there.

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“…Changes are manifest in a reduction in momentum in the model cell where the device is situated along with commensurate changes to turbulent kinetic energy and the turbulent kinetic energy dissipation rate. Sink terms, S Q , S K , and S ε , appropriate to each type of MHK device, represent the rate of momentum extraction, net change to turbulent kinetic energy, and the increase in turbulent kinetic energy dissipation rate, respectively [36]. In addition to the effects from the moving MHK device, the effects of affiliated support structures are also considered.…”

Section: Iiic2 Mhk Simulationmentioning

confidence: 99%

“…Over the last decade or so, various models have been proposed for S ε [36,42,43], but the simplest is used in this model:…”

mentioning

confidence: 99%

Simulating environmental changes due to marine hydrokinetic energy installations

James¹,

Seetho²,

Jones³

et al. 2010

Oceans 2010 MTS/Ieee Seattle

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Abstract-Marine hydrokinetic (MHK) projects will extract energy from ocean currents and tides, thereby altering water velocities and currents in the site's waterway. These hydrodynamics changes can potentially affect the ecosystem, both near the MHK installation and in surrounding (i.e., far field) regions. In both marine and freshwater environments, devices will remove energy (momentum) from the system, potentially altering water quality and sediment dynamics. In estuaries, tidal ranges and residence times could change (either increasing or decreasing depending on system flow properties and where the effects are being measured). Effects will be proportional to the number and size of structures installed, with large MHK projects having the greatest potential effects and requiring the most in-depth analyses. This work implements modification to an existing flow, sediment dynamics, and water-quality code (SNL-EFDC) to qualify, quantify, and visualize the influence of MHK-device momentum/energy extraction at a representative site. New algorithms simulate changes to system fluid dynamics due to removal of momentum and reflect commensurate changes in turbulent kinetic energy and its dissipation rate. A generic model is developed to demonstrate corresponding changes to erosion, sediment dynamics, and water quality. Also, bed-slope effects on sediment erosion and bedload velocity are incorporated to better understand scour potential.

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ONE- and TWO-Equation Models for Canopy Turbulence

Cited by 344 publications

References 65 publications

Estimation of In-Canopy Ammonia Sources and Sinks in a Fertilized Zea mays Field

Estimation of In-Canopy Ammonia Sources and Sinks in a Fertilized Zea mays Field

A Linearized $$k-\epsilon $$ k - ϵ Model of Forest Canopies and Clearings

Simulating environmental changes due to marine hydrokinetic energy installations

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