The effect of stratification on the aerodynamic roughness length and displacement height
Sergej Zilitinkevich, University of Helsinki, Helsinki, Finland; and I. Mammarella, A. Baklanov, and S. Joffre
The roughness length, and displacement height, characterize the resistance exerted by the roughness elements on turbulent flows and provide a conventional boundary condition for a wide range of turbulent-flow problems. Classical laboratory experiments and theories treat them as geometric parameters independent of the characteristics of the flow. In this paper, we demonstrate essential stability dependences – stronger for the roughness length (especially in stable stratification) and weaker but still pronounced for the displacement height. We develop a scaling-analysis model for these dependences and verify it against experimental data.
Joint Session 24, Modeling Tools for Urban and Complex Terrain Environments
Thursday, 15 January 2009, 3:30 PM-5:00 PM, Room 124A
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