简介：Abstract

In this talk I will show several examples of an interesting and surprising competition between buoyancy and Marangoni forces.

First, I will introduce the audience to the jumping oil droplet – and its sudden death – in a density stratified liquid consisting of water in the bottom and ethanol in the top: After sinking for about a minute, before reaching the equilibrium the droplet suddenly jumps up thanks to the Marangoni forces. This phenomenon repeats about 30-50 times, before the droplet falls dead all the sudden. We explain this phenomenon and explore the phase space where it occurs.

Next, I will focus on the evaporation of multicomponent droplets, for which the richness of phenomena keeps surprising us. I will show and explain several of such phenomena, namely evaporation-triggered segregation thanks to either weak solutal Marangoni flow or thanks to gravitational effects. The dominance of the latter implies that sessile droplets and pending droplets show very different evaporation behavior, even for Bond number << 1. I will also explain the full phase diagram in the Marangoni number vs Rayleigh number phase space, and show where Rayleigh convections rolls prevail, where Marangoni convection rolls prevail, and where they compete.

The research work shown in this talk combines experiments, numerical simulations, and theory. It has been done by and in collaboration with Yanshen Li, Yaxing Li, and Christian Diddens, and many others.

报告人介绍：Brief Biography

Detlef Lohse got his PhD on the theory of turbulence in Marburg/Germany in 1992. As a postdoc in Chicago and later in Marburg and Muenchen he worked on single bubble sonoluminescence. In 1998, he got appointed as Chair of Physics of Fluids at the University of Twente, The Netherlands, where he still is.  Lohse's present research subjects are turbulence and multiphase flow, biomedical flow, granular matter, and micro- and nanofluidics. Lohse is Associate Editor of Journal of Fluid Mechanics, Annual Review of Fluid Mechanics, and several other journals. He is Fellow of the American Physical Society, Division of Fluid Dynamics, and of IoP. He is a member of the German Academy of Sciences, a member of the Royal Dutch Academy of Sciences, and a member of the National Academy of Engineering (NAE) of the United States of America. He received various prizes such as the Spinoza Prize (2005), the Simon Stevin Prize (2009), two ERC-Advanced Grants (2011,2017), the Physica Prize (2011), the George K. Batchelor Prize for Fluid Dynamics (2012), the AkzoNobel Prize (2012), the American Physical Society Fluid Dynamics Prize (2017), the Balzan Prize (2018), and Max-Planck-Medal 2019 (German Physical Society DPG). He also set up the first (and up to now only) Dutch Max-Planck Center (2016, on Complex Fluid Dynamics).