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Complexity, segregation and pattern formation in rotating-drum flows

Gabriel Seiden

Department of Environmental Sciences and Energy Research,
Weizmann Institute of Science

The rotating horizontal drum is a unique experimental configuration which has served as a fertile tool in the investigation of various out-of-equilibrium phenomena ranging from solitary waves in pure liquids, through segregation in dilute suspensions, to avalanches in granular matter. In the first part of my talk I will present an overview on rotating-drum flows, utilizing a novel unified dimensional analysis which views the different realizations of rotating drum-flows as different regions in a generic dimensionless parameter space [1]. In the second part, I will focus on a particular flow realization, namely coating flow of a polymer solution partially filling the rotating drum. Here, I will present recent experimental results on an elastically driven instability, occurring for negligible Reynolds numbers. This instability manifests itself through localized plume-like bursts, perturbing the free liquid surface [2]. Plume merging leads to an area cascade with a time-independent flux, resulting in a power-law decay of the plume area distribution.

[1] G. Seiden and P. J. Thomas, Rev. Mod. Phys., 83, 1323 (2011).

[2] G. Seiden and V. Steinberg, Europhys. Lett. 96, 28004 (2011).