CAREER: Multiscale experimental framework on dynamics of deformable particles in turbulent dispersed multiphase flow

从云中的雨滴到生物反应堆和核反应堆中的气泡，自然界和工业应用中的多相流往往是湍流的，跨越了广泛的长度和时间尺度，对数值和实验方法构成了重大挑战。在表征球形颗粒分散的湍流多相流方面已经取得了重大进展；然而，关于另一大类由可变形液滴或气泡组成的分散相的研究却知之甚少。这些粒子可以在湍流中自由变形、翻滚、解体和结合，为本已复杂的问题增加了新的自由度。关键的问题是，这些可变形粒子的独特动力学统计是什么，以及如何表征它们与载波相位的复杂耦合。为了解决这些问题并获得对可变形粒子动力学的完整物理图景的洞察，该项目涉及从界面动力学到大规模统计的几个不同长度尺度的多尺度实验框架。为了得到两相的耦合，在拉格朗日框架下同时跟踪载流子相和分散相。这不仅使我们能够测量两相的速度，而且还能测量对两相之间的动量耦合更为重要的高阶导数，包括加速度和速度梯度张量。

From rain droplets in clouds to gas bubbles in bioreactors and nuclear reactors, multiphase flows occurring in nature and industrial applications are often turbulent, spanning a wide range of length and time scales and posing significant challenges to numerical and experimental methods. Significant progress has been made in characterizing the turbulent multiphase flow dispersed with spherical particles; much less is known, however, about another large category with dispersed phase consisting of deformable liquid drops or gas bubbles. Those particles can freely deform, tumble, break up and coalesce in turbulent flow, adding new degrees of freedom to an already complex problem. The key questions arise as to what are the statistics of unique dynamics of these deformable particles and how to characterize their complex couplings with the carrier phase. In order to address those questions and gain insights in the full physical picture of the dynamics of deformable particles, the project involves a multiscale experimental framework on several different length scales from interface dynamics to large-scale statistics. In order to obtain couplings of two phases, both the carrier phase and the dispersed phases will be tracked in the Lagrangian framework simultaneously. This enables us to measure, not only the velocity of both phases, but also those high-order derivatives, including acceleration and velocity gradient tensor, that are more important to the momentum couplings between two phases.