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Thursday, July 20, 2017
10:00 AM - 11:00 AM
CNLS Conference Room (TA-3, Bldg 1690)

Seminar

Dynamically dominant exact coherent structures in turbulent Taylor-Couette flow

Michael Krygier
Georgia Institute of Technology

Unstable Exact Coherent Structures (ECS), which are solutions to the Navier-Stokes equation, provide a connection between turbulence and dynamical systems and offer a method for exploiting the low dimensionality of weakly turbulent flows. We investigate ECS in an intermittent Taylor-Couette flow (TCF) found in a small-aspect-ratio geometry with counter-rotating cylinders (η = 0 . 5 , Γ = 1 , Rei = - 1200 , Reo = 1200). The presence of end-caps breaks the axial translational symmetry of TCF, but continuous rotational symmetry remains, which suggest that typical ECS should be the relative versions of equilibria and time-periodic orbits. Indeed, previous studies (Meseguer et al., 2009 and Deguchi, Meseguer & Mellibovsky, 2014) found several unstable traveling wave solutions (relative equilibria). We have shown that the dynamically dominant ECS for weakly turbulent TCF in the small-aspect-ratio geometry are relative periodic orbits (not relative equilibria), as evidenced by the frequent visits of their neighborhoods by the turbulent flow.

Host: Daniel M. Israel