Bulging and bending of Kelvin-Helmholtz billows controlled by symmetry and phase of initial perturbation

• Published in: Journal of physics. Conference series Vol. 216; no. 1; p. 012019
• Main Authors: Kit, E, Gerstenfeld, D, Gelfgat, A Y, Nikitin, N V
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.03.2010
• Subjects: Base flow; Bending; Bifurcations; Cross flow; Flow stability; Perturbation; Physics; Symmetry; Three dimensional flow; Two dimensional flow
• ISSN: 1742-6596; 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/216/1/012019

A computational study of two possible modes of instability of developed Kelvin-Helmholtz (KH) billows is carried out. It is shown that depending on one of three factors, (i) symmetry of initial perturbation in the cross-flow direction, (ii) phase shift of initial perturbation in the streamwise direction, or (iii) excitation of either spanwise or oblique initial wave, the resulting instability can set in as a spanwise bending or bulging of a two-dimensional KH roller. To ensure that the observed secondary bifurcations result from the linear instability the study is carried out considering a two-dimensional flow combined of a distorted mean flow and developed "frozen" KH billow in under and/or over-saturated state as a base flow subject to three-dimensional instabilities.