Secondary Instability of Two-Dimensional Coherent Structures in Shallow Mixing Layers

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Mohamed S Ghidaoui, Man Yue Lam

Friday 3 july 2015

8:30 - 8:45h at Amazon (level 1)

Themes: (ST) River and coastal engineering, (T) Water engineering

Parallel session: 14E. Engineering - River

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The secondary instability of two-dimensional coherent structures (2DCS) in shallow mixing layers is investigated. To this end, secondary stability analysis is performed. The results are compared tononlinear simulations of temporal shallow mixing layers performed with a shallow water model. The results show that there are two modes of instability for 2DCS in shallow mixing layers.By comparing stability analysis results with numerical simulations, it is suggested that the mergingof 2DCS in shallow mixing layers can be explained by the secondary instability of the 2DCS. The two modes of instability in the secondary instability of 2DCS in shallow mixing layers correspond to the two merging mechanisms of 2DCS, namely the pairing and shredding of 2DCS.