Towards an understanding of the mechanisms leading to air entrainment in the skimming fow over stepped spillways

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dc.contributor.authorZabaleta, Federico
dc.contributor.authorBombardelli, Fabián
dc.contributor.authorToro, Juan Pablo
dc.date.accessioned2021-07-21T00:28:51Z
dc.date.available2021-07-21T00:28:51Z
dc.date.issued2020-02
dc.descriptionIndexación: Scopuses
dc.description.abstractModern turbulence models allow for detailed numerical solutions, involving millions of data points and numerous degrees of freedom; these solutions have the potential to provide notable insights into the fows past hydraulic structures. In this paper, we present new analyses of a Detached-eddy simulation of the fow past stepped spillways in three dimensions, in order to investigate the coherent structures conducive to the phenomenon of air entrainment. The analyses focus on the spatial distributions of vorticity and velocity, as well as time series of the vorticity component in the transverse direction. A new index, Vn, is proposed in order to represent the spatial location of patches of vorticity magnitude, showing by defnition that time-averaged values of such index (Vn) constitute the fraction of time in which the vorticity exceeds n s−1 . When such average values are plotted for the central plane of the spillway, they strongly agree with plots of turbulent kinetic energy, conclusively connecting the vorticity patches with the turbulence intensities. The spatial evolution of velocity and vorticity components in a curved surface located at the experimental values of the thickness of the boundary layer indicates an important development of turbulence, manifested by large instantaneous values of the main fow variables. Three-dimensional plots of iso-surfaces of constant Vn and of turbulent kinetic energy show a similar growth rate, providing further evidence of the interconnection of variables. Finally, these results suggest that steps “compensate” the decay of turbulence by generating vorticity patches in between the steps, which they then become released to the fow and reach positions close to the free surfacees
dc.identifier.citationEnvironmental Fluid Mechanics Open Access Volume 20, Issue 2, Pages 375 - 3921 April 2020es
dc.identifier.issn15677419
dc.identifier.urihttp://repositorio.unab.cl/xmlui/handle/ria/19462
dc.language.isoenes
dc.publisherSpringeres
dc.subjectStepped spillway · Non-aerated fow · Skimming fow · Detached eddy simulation (DES) · Particle image velocimetry (PIV) · Vorticity · Turbulent kinetic energyes
dc.titleTowards an understanding of the mechanisms leading to air entrainment in the skimming fow over stepped spillwayses
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