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Title: Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence

Abstract

Studying turbulence in vegetation canopies is vital 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 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 techniques such as measures from information theory and coupled oscillator analysis are used tomore » extract the coherent structures associated with the two motions. It can be said 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.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karlsruhe Inst. of Technology (KIT) (Germany)
  2. Karlsruhe Inst. of Technology (KIT) (Germany)
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
German research Foundation (DFG); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1558041
Report Number(s):
LA-UR-17-29138
Journal ID: ISSN 1812-2116
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Hydrology and Earth System Sciences Discussions (Online)
Additional Journal Information:
Journal Name: Hydrology and Earth System Sciences Discussions (Online); Journal ID: ISSN 1812-2116
Publisher:
European Geosciences Union (EGU)
Country of Publication:
United States
Language:
English
Subject:
Earth Sciences; canopy turbulence

Citation Formats

Banerjee, Tirtha, De Roo, Frederik, and Linn, Rodman. Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence. United States: N. p., 2017. Web. doi:10.5194/hess-2017-595.
Banerjee, Tirtha, De Roo, Frederik, & Linn, Rodman. Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence. United States. doi:10.5194/hess-2017-595.
Banerjee, Tirtha, De Roo, Frederik, and Linn, Rodman. Wed . "Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence". United States. doi:10.5194/hess-2017-595. https://www.osti.gov/servlets/purl/1558041.
@article{osti_1558041,
title = {Revisiting Kelvin Helmholtz Instabilities and von Kármán Vortices in Canopy Turbulence},
author = {Banerjee, Tirtha and De Roo, Frederik and Linn, Rodman},
abstractNote = {Studying turbulence in vegetation canopies is vital 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 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 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 said 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.},
doi = {10.5194/hess-2017-595},
journal = {Hydrology and Earth System Sciences Discussions (Online)},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {10}
}

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