Open access
Datum
2017-06-10Typ
- Journal Article
Abstract
It was previously observed by Krug et al. (J. Fluid Mech., vol. 765, 2015, pp. 303–324) that the surface area Aη of the turbulent/non-turbulent interface (TNTI) in gravity currents decreases with increasing stratification, significantly reducing the entrainment rate. Here, we consider the multiscale properties of this effect using direct numerical simulations of temporal gravity currents with different gradient Richardson numbers Rig. Our results indicate that the reduction of Aη is caused by a decrease of the fractal scaling exponent β, while the scaling range remains largely unaffected. We further find that convolutions of the TNTI are characterized by different length scales in the streamwise and wall-normal directions, namely the integral scale h and the shear scale lSk = k1/2/S (formed using the mean shear S and the turbulent kinetic energy k) respectively. By recognizing that the anisotropy implied by the different scaling relations increases with increasing Rig, we are able to model the Rig dependence of β in good agreement with the data. Mehr anzeigen
Persistenter Link
https://doi.org/10.3929/ethz-b-000192184Publikationsstatus
publishedExterne Links
Zeitschrift / Serie
Journal of Fluid MechanicsBand
Seiten / Artikelnummer
Verlag
Cambridge University PressThema
Geophysical and geological flows; gravity currents; stratified turbulenceOrganisationseinheit
09454 - Holzner, Markus (SNF-Prof.) (ehemalig) / Holzner, Markus (SNF-Prof.) (former)
Anmerkungen
It was possible to publish this article open access thanks to a Swiss National Licence with the publisher.