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Large eddy simulation of planetary boundary layers with dynamic mixed subfilter closure
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
In: Environmental Fluid MechanicsArticle in journal (Refereed) Submitted
URN: urn:nbn:se:uu:diva-90146OAI: oai:DiVA.org:uu-90146DiVA: diva2:162385
Available from: 2003-02-19 Created: 2003-02-19Bibliographically approved
In thesis
1. Large Eddy Simulation of Non-Local Turbulence and Integral Measures of Atmospheric Boundary Layers
Open this publication in new window or tab >>Large Eddy Simulation of Non-Local Turbulence and Integral Measures of Atmospheric Boundary Layers
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A new large eddy simulation (LES) code is developed and used to investigate non-local features of turbulent planetary boundary layers (PBLs). The LES code is based on filtered Navier-Stokes equations, which describe motions of incompressible, Boussinesq fluid at high Reynolds numbers. The code computes directly large-scale, non-universal turbulence in the PBL whereas small-scale, universal turbulence is parameterized by a dynamic mixed subgrid closure. The LES code is thoroughly tested against high quality laboratory and field data.

This study addresses non-local properties of turbulence which emphasis on the stable stratification. Its basic results are as follows. The flow stability in PBLs is generally caused by two mechanisms: the negative buoyancy force (in the stable density stratification) and the Coriolis force (in the rotating system). The latter stabilizes the flow if the earth’s vorticity and the turbulent vorticity are anti-parallel. The Coriolis force stability suppresses large-scale turbulence and makes large eddies asymmetric. The density stratification suppresses vertical scales of turbulence. Joint actions of the Coriolis and the buoyancy forces result in a more complex behavior of turbulence. Particularly, the layers of vigorous turbulence may appear in the course of development of low-level jets in baroclinic atmosphere.

Non-local effects determine integral measures of PBLs, first of all the PBL depth. This study clearly demonstrates its pronounced dependences on the Coriolis parameter, the Kazanski-Monin internal stability parameter, and newly introduced imposed-stability and baroclinicity parameters. An LES database is created and used to validate an advanced PBL-depth formulation. LES support the idea that PBLs interact with the stably stratified free flow through the radiation of gravity waves, excited by large turbulent eddies at the interface.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 30 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 800
Meteorology, Planetary boundary layers, large eddy simulations, non-local turbulence, Meteorologi
National Category
Meteorology and Atmospheric Sciences
Research subject
urn:nbn:se:uu:diva-3321 (URN)91-554-5519-0 (ISBN)
Public defence
2003-03-24, Axel Hambergsalen, Geocentrum, Uppsala, 10:00
Available from: 2003-02-19 Created: 2003-02-19Bibliographically approved

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