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器和核反应堆中的气泡，自然界和工业应用中发生的多相流通常是湍流，跨越广泛的长度和时间尺度，对数值和实验方法提出了重大挑战。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，对另一个由可变形液滴或气泡组成的分散相的大类知之甚少。这些粒子可以在湍流中自由变形、翻滚、分裂和合并，为本已复杂的问题增加了新的自由度。出现的关键问题是什么是这些可变形粒子的独特动力学的统计，以及如何表征其复杂的耦合与载波相位。为了解决这些问题，并获得可变形粒子动力学的完整物理图像的见解，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。为了获得两相的耦合，将在拉格朗日框架中同时跟踪载体相和分散相。这使得我们不仅可以测量两相的速度，还可以测量那些对两相之间的动量耦合更重要的高阶导数，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.