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IGM Colloquium: Prof. Shmuel Rubinstein, Harvard University

© Work of Prof. Shmuel Rubinstein

© Work of Prof. Shmuel Rubinstein

The physics of crushing and smashing: Cascades and cataclysmic changes, Tuesday 6 November 2018 12:15 - 13:15 MED 0 1418

Many of the big problems we are facing involve far from equilibrium systems that entail a cataclysmic change. Climate, turbulence and earthquakes, developmental biology, aging death, and even evolution. These phenomena are rare (sometimes occurring only once) and are entirely irreversible. While understanding the physics of such irreversible processes is of both fundamental and practical importance, these problems also pose unique challenges. These challenges, as they manifest in turbulence, were beautifully portrayed by Richardson:
“Big whirls have little whirls that feed on their velocity, and little whirls have lesser whirls and so on to viscosity”
Lewis Fry Richardson (1922)

In his short verse, Richardson captures the essence of the turbulent cascade—the conveyance of kinetic energy across scales that underlies the universal dynamics of turbulent flows. Indeed, such conveyance of important physical quantities (energy, stress, frustration and even information) down and up a vast range of scales underlines the dynamics of many systems. The same applies to how a multi-contact frictional interface will form and break or how correlated defect structures determine the strength of a space-rocket, how an intricate network of creases will form when we crumple a thin sheet or when soda can is smashed. The challenge in understanding these systems is in capturing the events as they occur, keeping up with the dynamics on all scales and at all times. Here, I will review our work on several key irreversible system and introduce the new tools we developed to address their unique evolution and discuss the interesting physics we learned. Specifically, I will discuss: turbulence in the collision of vortex rings, splashing, friction, fracture and failure.

Rubinstein's interests lie in understanding the non-linear dynamics of hard, soft and liquid systems. Rubinstein received a Ph.D. degree in Physics from the Hebrew University, Jerusalem, in 2010. At Harvard, Professor Rubinstein is developing a program in soft matter physics that focuses on complex interfaces. His interests are in experimental, out of equilibrium, and non-linear physics. Specifically, his lab focuses on developing cutting-edge experimental techniques to investigate systems where interfacial formation, deformation and collapse dominate the dynamics. He collaborates closely with theorists to explore three main thrusts: (1) disordered solid and liquid systems, (2) nonlinear instabilities in solids and liquids and (3) development of bacterial biofilms. Each of these systems of interest highlights a beautiful, yet poorly understood phenomenon that Rubinstein seeks to elucidate, including: How do things slide? How do things break? Why do soft materials age? How does paper crumple? Why do drops splash? How do micron-size bacteria engineer huge biofilms.

Tuesday 6 November 2018 12:15 - 13:15 MED 0 1418https://memento.epfl.ch/event/igm-colloquium-the-physics-of-crushing-and-smashin/