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Seminar
Speaker
Balachandra Suri (Institute of Science and Technology (IST), Austria)
Date & Time
Thu, 21 January 2021, 15:30 to 17:00
Venue
Online seminar
Resources
Abstract

Turbulence is widely regarded as the last unsolved problem of classical physics. Despite the availability of well-defined governing equations, a tractable framework that predicts'' the dynamical and statistical properties of (even weak) turbulence has eluded scientists. In this talk, we demonstrate that such a framework can be developed using unstable nonchaotic solutions of the Navier-Stokes equation, called Exact Coherent States (ECS). In a moderately turbulent quasi-two-dimensional laboratory flow, we  show that fleeting appearance of coherent structures is related to the dynamical significance of ECS in turbulence.  We then construct a low-dimensional model for flow dynamics near an ECS and forecast turbulent evolution for a short duration.  Analyzing their statistical significance, we show that frequently appearing ECS capture statistical averages (e.g., rate of energy dissipation) of turbulent flows accurately. Finally, we  provide a geometrical description of transient turbulence using dynamical connections between ECS.