The TRR 181 seminar is held by Dr. Nazmi Burak Budanur (Max Planck Institute for the Physics of Complex Systems) on October 25, 15:15 Uhr in in Grindelberg 5, Room 4007.

Reduced-order modeling of turbulent flows in terms of coherent structures

Abstract

A large volume of experimental and numerical evidence suggests that the dynamics of turbulent flows are underpinned by "coherent structures," i.e. large-scale flow patterns that persist for long times. In addition to their observations in laboratory and computer experiments, the theoretical works of the past forty years have determined causal connections between the coherent structures, such as the self-sustaining cycle of streaks and vortices in shear flows. Altogether, these developments suggest that it should be possible to utilize coherent structures in reduced-order turbulence models, yet, the methodology for developing such models remains an open problem. In the first part of my talk, I will introduce one approach to this problem based on the coarse-graining of the state space using periodic orbits and present the results of its application to the sinusoidally-driven flow in a triply-periodic domain.
In the second part, I will give examples from my recent research on data-driven techniques ƒor tackling the same problem in more complicated settings.

References: 

[1] G. Yalnız, N. B. Budanur, Inferring symbolic dynamics of chaotic
flows from persistence, Chaos 30, 033109 (2020), arXiv:1910.04584.
[2] G. Yalnız, B. Hof, and N. B. Budanur, Coarse graining the state space of a
turbulent flow using periodic orbits, Phys. Rev. Lett. 126, 244502 (2021)
arXiv:2007.02584.
[3] E. Marensi, G. Yalnız, B. Hof, and N. B. Budanur, Symmetry-reduced Dynamic
Mode Decomposition of Near-wall Turbulence, arXiv:2101.07516.