Abstract
We present DNS of stably-stratified, open-channel flows and capped Ekman layers, where the stable stratification is imposed by ground cooling. These flows have very different outer regions, yet the development of the stratification and the flow fields in their buffer regions is very similar. In particular, in both cases turbulence collapse occurs when \(Lu_\tau /\nu \lesssim 100\), suggesting that this is a local process, independent of the details of the outer flow. Analysis of the spectra and energy budgets shows that stable stratification leads to an increase in normalized production, dissipation and pressure strain-rate (inter-component energy transfer). These changes are associated with the increase in the mean shear, which in turn increases the energy at the small scales. On the other hand, the large scales are damped by the direct effect of the stable stratification.
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Acknowledgements
This work has been supported by ARO Grant No. W911NF-08-1-0155. The numerical resources provided by the DoD HPCMP are gratefully acknowledged.
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© 2018 CISM International Centre for Mechanical Sciences
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Flores, O., Riley, J.J. (2018). Energy Balance in Stably-Stratified, Wall-Bounded Turbulence. In: Clercx, H., Van Heijst, G. (eds) Mixing and Dispersion in Flows Dominated by Rotation and Buoyancy. CISM International Centre for Mechanical Sciences, vol 580. Springer, Cham. https://doi.org/10.1007/978-3-319-66887-1_4
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DOI: https://doi.org/10.1007/978-3-319-66887-1_4
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