Employing numerical simulations, we provide an accurate insight into the of heat transfer mechanisms in the Rayleigh-Bénard convection of concentrated emulsions with finite-size droplets. We focus on the unsteady dynamics characterizing the thermal convection of these complex fluids close to the transition from conductive to convective states, where the heat transfer phenomenon, expressed in terms of the Nusselt number Nu, is characterized by pronounced fluctuations triggered by collective droplets motion [Pelusi et al., Soft Matter 17(13), 3709 - 3721 (2021)]. By systematically increasing the droplet concentration, we show how these fluctuations emerge along with the segregation of "extreme events" in the boundary layers, causing intermittent bursts in the heat flux fluctuations. Furthermore, we quantify the extension $S$ and the duration $\mathcal{T}$ of the coherent droplet motion accompanying these extreme events via a suitable statistical analysis involving the droplets displacements. We show how the increase in droplet concentration results in a power-law behaviour of the probability distribution function of $S$ and $\mathcal{T}$ and how this outcome is robust at changing the analysis protocol. Our work offers a comprehensive picture, linking macroscopic heat transfer fluctuations with the statistics of droplets at the mesoscale.
Rayleigh-Bénard thermal convection in emulsions: a short review
Istituto per le Applicazioni del Calcolo, CNR（意大利国家研究委员会计算应用研究所）；INFN, Sezione Roma “Tor Vergata”（罗马“托尔维加塔”分部意大利国家核物理研究所）；Department of Physics & INFN, Tor Vergata University of Rome（罗马托尔维加塔大学物理系及意大利国家核物理研究所）；Sino-Europe Complex Science Center, School of Mathematics North University of China（中欧复杂科学中心，中北大学数学学院）
Forced generation of simple and double emulsions in all-aqueous system
我们报告了一种易于实施的方法，允许直接生成水包水（w/w）单一乳液。该方法依赖于驱动乳液分散相流动的压力的直接扰动。由于瑞利-高原不稳定性引起的扰动的增长，所产生的内射流被诱导破碎成液滴[L。Rayleigh，Proc. R. Soc. London 29，71-97（1879）];这导致单分散液滴的形成。通过在改性的微流体装置上实施该方法，我们直接产生水包水包水（w/w/w）双重乳液，其对封装液滴的大小和数量具有良好的控制。我们的方法提出了一种将基于液滴的微流体应用于完全基于水的系统的新途径。
A quantitative comparison of physical accuracy and numerical stability of Lattice Boltzmann color gradient and pseudopotential multicomponent models for microfluidic applications
