Intermittent Turbulence in Stratified Flow over a Canopy

S. Boing, H.J.J. Jonker, B.J.H. van de Wiel, A.F. Moene

Research output: Chapter in Book/Report/Conference proceedingConference paper

Abstract

During the night turbulence can often be very intermittent, occurring in sudden vigorous bursts after prolonged periods of low-intensity. Several mechanisms have been proposed to explain intermittency. The present study focuses on the role of porous surface elements, which influence the mean wind profile near the surface and therefore the shear characteristics. The shape of this profile plays a vital role in the mechanism that causes the flow to destabilize. Direct numerical simulations of a pressure driven stably stratified flow are used to study the development of initial instabilities into breaking waves and the possibility of a subsequent collapse of turbulence and return to a weakly turbulent state. To better understand the parameter space associated with the occurrence of intermittency, we conduct a linear stability analysis which provides critical values for the Richardson number in relation to the canopy characteristics. This enables one to make an a-priori educated guess of the conditions that favor intermittency, which are subsequently studied in more detail using the DNS
Original languageEnglish
Title of host publication19th Symposium on Boundary Layers and Turbulence Annual Meeting of the European Meteorological Society, 2-6 August 2010, Keystone, Colorado, USA, 1-6 August 2010
Place of PublicationBoston
PublisherAMS
Pages7.2 (9 pp)
Publication statusPublished - 2010
Event19th Symposium on Boundary Layers and Turbulence - Keystone, United States
Duration: 1 Aug 20106 Aug 2010

Conference

Conference19th Symposium on Boundary Layers and Turbulence
CountryUnited States
CityKeystone
Period1/08/106/08/10

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Boing, S., Jonker, H. J. J., van de Wiel, B. J. H., & Moene, A. F. (2010). Intermittent Turbulence in Stratified Flow over a Canopy. In 19th Symposium on Boundary Layers and Turbulence Annual Meeting of the European Meteorological Society, 2-6 August 2010, Keystone, Colorado, USA, 1-6 August 2010 (pp. 7.2 (9 pp)). Boston: AMS.