LES of Kármán vortex streets in the atmospheric boundary layer
Responsible: Rieke Heinze
Project type: Diplomarbeit (equivalent to master thesis)
Duration: 15/10/2008-14/10/2009

Atmospheric vortex streets consist of mesoscale eddies with vertical axis in the wake of large islands. They resemble classical Kármán vortex streets which occur in laboratory experiments behind a cylinder. The islands after which vortex streets appear typically have diameters about 20km and mountain tops about 2-4km. Usually, vortex streets can be found in the stratocumulus capped mixed layer over the ocean when there is a strong elevated inversion well below the island top. Since then, the air is forced to go mainly around the mountain and the stratocumulus clouds act as tracer.

The object of the project is the investigation of atmospheric vortex streets with aid of LES. The topography consists of a single idealized mountain. Characteristic parameters like shedding rate or propagation velocity shall be determined. At first, the dry version of PALM is used to generate Kármán like vortex streets. Then, it is planned to simulate a stratocumulus capped boundary layer with vortex street like cloud pattern.

An animation of a Kármán vortex street can be found in our movie gallery.