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|Title:||A large-eddy simulation study on vortex-ring collisions upon round cylinders||Authors:||New, Tze How
Gotama, Gabriel Jeremy
Vevek, U. S.
|Keywords:||Engineering::Mechanical engineering||Issue Date:||2021||Source:||New, T. H., Gotama, G. J. & Vevek, U. S. (2021). A large-eddy simulation study on vortex-ring collisions upon round cylinders. Physics of Fluids, 33(9), 094101-. https://dx.doi.org/10.1063/5.0057475||Journal:||Physics of Fluids||Abstract:||A large-eddy simulation based numerical study was conducted on head-on collisions between vortex-rings and round cylinders. The vortex-ring Reynolds number was Re = 4000, while the ratio of the cylinder diameter to vortex-ring diameter (i.e., diameter ratio, D/d) was varied from 4 to 1. Vortical behavior predicted by the present simulations is observed to agree well with an earlier experimental study [New, T. H., and Zang, B., “Head-on collisions of vortex rings upon round cylinders,” J. Fluid Mech. 833, 648 (2017)]. The present simulations also reveal additional flow details on the vortex dynamics and vortex-core trajectories, which have not been observed previously. First, vortex-dipoles produced by D/d ≤ 2 cylinders are cross sections of elliptic vortex-ringlets formed via vortex disconnection/reconnection of secondary vortex-ring segments. Second, the aspect ratio of the elliptic vortex-ringlets increases when a smaller diameter-ratio cylinder is used, and finally, they undergo axis-switching behavior. Furthermore, up to three sets of tertiary vortex-ring cores are formed along the D/d = 2 and 1 cylinder straight-edges where they subsequently merge with the secondary vortex-ring cores within the confines of the primary vortex-ring cores. This merged vortex core moves toward the collision axis and forms an inner vortex-dipole with a wall separated vortex. Along the convex surface, up to two sets of tertiary vortex-ring cores are observed for D/d = 2 and 1 cylinders, and trajectories of the vortex-dipoles agree well with the past experimental results. These observations support the notion that higher vortex-stretching levels resulting from the use of small diameter-ratio cylinders with higher surface curvatures underpin the wide range of vortical behavior observed here.||URI:||https://hdl.handle.net/10356/153750||ISSN:||1070-6631||DOI:||10.1063/5.0057475||Rights:||© 2021 Author(s). All rights reserved. This paper was published by AIP Publishing in Physics of Fluids and is made available with permission of Author(s).||Fulltext Permission:||open||Fulltext Availability:||With Fulltext|
|Appears in Collections:||MAE Journal Articles|
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Updated on May 17, 2022
Updated on May 17, 2022
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