CAREER: Transition to Turbulence and Mixing for Rayleigh Taylor Instability with Acceleration Reversal

该建议的重点是使用计算和实验组件来阐明变密度湍流中的混合（即，当不同密度的两种流体由于湍流而混合时）。在这一领域的大量先前研究集中在对流场没有影响的质量传输的更容易的情况下，以及规范流（例如，槽流、射流、边界层）。拟议的研究旨在克服与非规范流（这些流是在工业和自然界中常见的）的实验研究相关的困难，并在新的设置中以前所未有的细节测量湍流量。这些工作可以开辟流体动力学其他领域的发展，包括多相流，传热和燃烧以及冲击驱动流。拟议的教育活动包括让当地一所社区学院参与PI的研究，开发一个教育视频系列，通过iTunes提供，并将8至12年级学生纳入夏令营进行研究。本文的目的是通过实验和模拟研究变密度流中的瑞利-泰勒不稳定性。这种不稳定性发生在两种不同密度的流体接触时，并且较轻的流体加速了较重的流体。PI已经建立了一个相当独特的实验设施，使他能够完成拟议工作的实验部分。它是一种允许控制旋转系统中流体加速和减速的装置。实验系统甚至允许从加速切换到减速，然后进一步逆转加速。PI建议使用平面激光诱导荧光，PLIF，和立体粒子图像测速获得高阶统计的流量和标量场。为了用最先进的模拟来补充实验，PI与LANL建立了合作关系，对流动进行直接数值模拟（DNS）。

1453056BanerjeeThe focus of this proposal is to use both computational and experimental components to elucidate mixing in variable density turbulence (i.e., when two fluids of different density mix because of turbulence). The bulk of prior research in this area has focused on the easier case of transport of mass without effects on the flow field, and on canonical flows (e.g., channel flows, jet flows, boundary layers). The proposed research aims to overcome the difficulties associated with experimental studies of non-canonical flows (these flows are the ones commonly found in industry and in nature), and to measure turbulence quantities in unprecedented details in new settings. Such work can open up developments in other areas of fluid dynamics, including multiphase flow, heat transfer and combustion and shock-driven flows. The proposed educational activities include the involvement of a local community college in the PI's research, the development of an educational video series that would be available through iTunes, and the inclusion of 8th to 12th graders in summer camps for research. The goal of the proposed research is to investigate the Rayleigh-Taylor instability in variable density flows using both experiments and simulations. This instability occurs when two fluids of different density are in contact, and the denser fluid is accelerated by the lighter fluid. The PI has built a rather unique experimental facility that would enable him to complete the experimental part of the proposed work. It is a device that allows the control of acceleration and deceleration of the fluid in a rotating system. The experimental system even allows the switch from acceleration to deceleration and then further reversals of acceleration. The PI proposes the use of planar laser-induced fluorescence, PLIF, and stereo-Particle Image Velocimetry to obtain high order statistics for the flow and scalar fields. In order to complement the experiments with state-of-the-art simulations, the PI has established a collaboration with LANL to conduct direct numerical simulations (DNS) of the flow.