[Seminar] Mr. Stefano Brizzolara "Unveiling the signature of surface tension on immiscible Rayleigh-Taylor turbulence"

Speaker

Mr. Stefano Brizzolara / ETH Zurich

Title

Unveiling the signature of surface tension on immiscible Rayleigh-Taylor turbulence

Abstract

The Rayleigh-Taylor instability (RTI) originates when a heavier fluid is initially placed on the top of a lighter fluid in the presence of gravity. At late times, the RTI evolves in a self-similar turbulent mixing layer, sustained by the continuous conversion of potential into kinetic energy. If the two phases are insoluble, the surface tension prevents them to mix at the molecular level. Notwithstanding, the turbulence fragments one fluid into the other, generating an emulsion-like state where the characteristic bubble size decreases in time according to a power law scaling that results from a balance between the rising kinetic energy and the surface energy density. In this seminar I draw a phenomenological picture that describes the Rayleigh-Taylor emulsification process following the reasoning of Chertkov et al. [1], and present the first experimental and numerical evidences that validate the phenomenological prediction.

[1] Chertkov, M., Kolokolov, I. and Lebedev, V. "Effects of surface tension on immiscible Rayleigh-Taylor turbulence." PRE 71.5 (2005): 055301.

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