Eighth Symposium on the Urban Environment
The Energy Committee


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.

wrf recording  Recorded presentation

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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