Direct numerical simulations of stratified open channel flows
Deusebio E, Schlatter P, Brethouwer G, Lindborg E (2011)
Publication Type: Conference contribution
Publication year: 2011
Publisher: Institute of Physics Publishing
Book Volume: 318
Conference Proceedings Title: Journal of Physics: Conference Series
Event location: POL
DOI: 10.1088/1742-6596/318/2/022009
Abstract
We carry out numerical simulations of wall-bounded stably stratified flows. We mainly focus on how stratification affects the near-wall turbulence at moderate Reynolds numbers, i.e. Reτ = 360. A set of fully-resolved open channel flow simulations is performed, where a stable stratification has been introduced through a negative heat flux at the lower wall. In agreement with previous studies, it is found that turbulence cannot be sustained for h/L values higher than 1.2, where L is the so-called Monin-Obukhov length and h is the height of the open channel. For smaller values, buoyancy does not re-laminarize the flow, but nevertheless affects the wall turbulence. Near-wall streaks are weakly affected by stratification, whereas the outer modes are increasingly damped as we move away from the wall. A decomposition of the wall-normal velocity is proposed in order to separate the gravity wave and turbulent flow fields. This method has been tested both for open channel and full channel flows. Gravity waves are likely to develop and to dominate close to the upper boundary (centerline for full channel). However, their intensity is weaker in the open channel, possibly due to the upper boundary condition. Moreover, the presence of internal gravity waves can also be deduced from a correlation analysis, which reveals (together with spanwise spectra) a narrowing of the outer structures as the stratification is increased.
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How to cite
APA:
Deusebio, E., Schlatter, P., Brethouwer, G., & Lindborg, E. (2011). Direct numerical simulations of stratified open channel flows. In Journal of Physics: Conference Series. POL: Institute of Physics Publishing.
MLA:
Deusebio, E., et al. "Direct numerical simulations of stratified open channel flows." Proceedings of the 13th European Turbulence Conference, ETC13, POL Institute of Physics Publishing, 2011.
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