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Turbulence structure in a diabatically heated forest canopy composed of fractal Pythagoras trees

Schröttle, Josef und Dörnbrack, Andreas (2013) Turbulence structure in a diabatically heated forest canopy composed of fractal Pythagoras trees. Theoretical and Computational Fluid Dynamics, 27, Seiten 337-359. Springer. doi: 10.1007/s00162-012-0284-8. ISSN 0935-4964.

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Offizielle URL: http://link.springer.com/article/10.1007%2Fs00162-012-0284-8

Kurzfassung

We investigate the turbulent flow through a heterogeneous forest canopy by high-resolution numerical modeling. For this purpose, a novel approach to model individual trees is implemented in our large-eddy simulation (LES). A group of sixteen fractal Pythagoras trees is placed in the computational domain and the tree elements are numerically treated as immersed boundaries. Our objective is to resolve the multiscale flow response starting at the diameter of individual tree elements up to the depth of the atmospheric surface layer. A reference run, conducted for the forest flow under neutral thermal stratification, produces physically meaningful turbulence statistics. Our numerical results agree quantitatively with data obtained from former field-scale LESs and wind tunnel experiments. Furthermore, the numerical simulations resolve vortex shedding behind individual branches and trunks as well as the integral response of the turbulent flow through the heterogeneous forest canopy. A focus is the investigation of the turbulence structure of the flow under stable thermal stratification and in response to the heating of the fractal tree crowns. For the stratified flows, statistical quantities, e.g. turbulent kinetic energy and vorticity, are presented and the turbulent exchange processes of momentum and heat are considered in detail. The onset and formation of coherent structures such as elevated shear layers above the diabatically heated forest canopy are analyzed. For the stably stratified flow, temperature ramps above the forest canopy were simulated in agreement with previous observations. Thermally driven vortices with a typical diameter of the canopy height were simulated when the tree crowns were diabatically heated. The impact of the coherent flow structures on the heat flux is investigated.

elib-URL des Eintrags:https://elib.dlr.de/81315/
Dokumentart:Zeitschriftenbeitrag
Titel:Turbulence structure in a diabatically heated forest canopy composed of fractal Pythagoras trees
Autoren:
AutorenInstitution oder E-Mail-AdresseAutoren-ORCID-iDORCID Put Code
Schröttle, JosefDLRNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Dörnbrack, AndreasDLRNICHT SPEZIFIZIERTNICHT SPEZIFIZIERT
Datum:15 September 2013
Erschienen in:Theoretical and Computational Fluid Dynamics
Referierte Publikation:Ja
Open Access:Ja
Gold Open Access:Nein
In SCOPUS:Ja
In ISI Web of Science:Ja
Band:27
DOI:10.1007/s00162-012-0284-8
Seitenbereich:Seiten 337-359
Verlag:Springer
Name der Reihe:Theoretical and Computational Fluid Dynamics
ISSN:0935-4964
Status:veröffentlicht
Stichwörter:Forest canopy, Fractal trees, Heat, Atmospheric boundary layer, Turbulence
HGF - Forschungsbereich:Energie
HGF - Programm:Erneuerbare Energie
HGF - Programmthema:keine Zuordnung
DLR - Schwerpunkt:Energie
DLR - Forschungsgebiet:E SF - Solarforschung
DLR - Teilgebiet (Projekt, Vorhaben):E - Windenergie (alt)
Standort: Oberpfaffenhofen
Institute & Einrichtungen:Institut für Physik der Atmosphäre > Wolkenphysik und Verkehrsmeteorologie
Hinterlegt von: Freund, Jana
Hinterlegt am:28 Feb 2013 15:55
Letzte Änderung:06 Sep 2019 15:18

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