Buoyancy Driven Turbulence Beyond Self-Similar Equilibrium

0967672 Banerjee自相似性是湍流研究中出现的一个重要概念，其中通常假设初始条件（IC）的记忆在后期丢失，并且湍流发展到平衡（即自相似）状态。然而，最近的研究表明，只有特殊的湍流是真正的自相似。浮力驱动湍流中的实验和计算表明，后期湍流可以受到接种到流中的IC的影响，并且这些IC的记忆不会丢失。这为预测和设计后期浮力驱动的湍流提供了一个绝佳的机会，该湍流将完全发展的平衡概念抛在后面，并通过规定的IC来拥抱后期湍流，这些IC可以增强或抑制或保持这些流动中的湍流强度/结构。拟议研究计划的目标是评估IC的后期特征，这将使人们更好地了解混合主导的浮力问题，并在热交换器、化学反应堆、气候动力学、污染物扩散、惯性约束聚变和天体物理学中得到广泛应用。流动。研究包括实验和模拟。实验推力将涉及一个新的两轮高加速实验，使用控制IC的实验研究RT流的后期湍流物质（分子）混合。高保真诊断，包括组合的快速粒子成像测速/平面激光诱导荧光（f-PIV/PLIF）。这将提供每个实验中的IC的详细数据，以及流速的现场测量、密度的统计概率密度函数、速度波动和相关的湍流相关性和互相关。此外，隐式大涡模拟（ILES）计划通过验证和验证（V V）的模拟与实验交叉耦合，因此提供额外的详细数据集，以研究设计的IC的后期效果。智力优点：所提出的工作的智力优点涉及使用的实验和计算数据集：（a）检查的作用IC控制的分子混合动力学;（B）提供有价值的信息主动控制湍流混合发生在各种应用程序中的这种流动。此外，拟议的研究预计会导致新的发现有关的混合过程，这也可以用来扩展湍流理论超越传统的Kolmogorov的想法，这是与存在的惯性范围动力学和小尺度的普遍性。更广泛的影响：拟议的研究远远超出了我们对浮力驱动流的兴趣，并结合了系统设计初始和边界条件的可能性，用于后期湍流的被动控制。在教育方面，它将帮助支持两名研究生，并将向学生介绍湍流研究生课程中的前沿研究思想。本科研究人员将通过密苏里州S T-OURE（本科研究经验的机会）计划。谁将执行这项研究的大部分学生将积极招募来自代表性不足的群体（妇女和少数民族）在密苏里州ST通过妇女在科学工程（WISE）计划在校园里。此外，与洛斯阿拉莫斯国家实验室（LANL）的积极合作将有助于这项工作的潜在影响，预计将导致研究生在完成学位后的未来研究机会。

0967672BanerjeeSelf similarity is an important concept that arises in the study of turbulent flows, in which an assumption is often made that memory of initial conditions (ICs) are lost at late time and the turbulence develops to a equilibrium (i.e. self similar) state. However, recent studies have indicated that only special turbulent flows are truly self similar. Experiments and computations in buoyancy driven turbulence have indicated that late time turbulence can be affected by ICs seeded into the flow and memory of these ICs are not lost. This presents a remarkable opportunity to predict and design late time buoyancy driven turbulence that leaves behind the fully developed equilibrium concept, and embrace late time turbulence through prescribed ICs that either enhance, or suppress, or maintain turbulence intensity/structure in these flows. The objective of the proposed research program is to evaluate late-time signatures of ICs that will result in a better understanding of mix dominated buoyancy problems with widespread applications in heat exchangers, chemical reactors, climate dynamics, pollutant dispersion, inertial confinement fusion, and, astrophysical flows. The research includes experiments and simulations. The experimental thrust will involve a novel two wheel high acceleration experiment that uses controlled ICs to experimentally study the late time turbulent material (molecular) mixing for RT flows. High fidelity diagnostics which include a combined fast-Particle Imaging Velocimetry/Planar Laser Induced Fluorescence (f-PIV/PLIF). This will provide detailed data of ICs in each experiment, and field measurements of flow velocities, statistical probability density functions of density, velocity fluctuations and associated turbulence correlations and cross correlations. In addition, implicit Large Eddy Simulations (ILES) are planned to cross-couple with the experiment via validation and verification (V&V) of the simulation and therefore provide additional detailed data sets to study the late-time effect of designed ICs. Intellectual Merits:The intellectual merits of the proposed work involve usage of the experimental and computational data sets to: (a) examine the role of ICs to control the molecular mixing dynamics; (b) provide valuable information on active control of turbulent mixing as occurs in various applications of such flows. In addition, the proposed research is expected to result in new discoveries about the mixing process which can also be used to extend turbulence theory beyond the traditional ideas of Kolmogorov which is related to the existence of inertial range dynamics and small scale universality. Broader Impacts:The proposed research extends well beyond our interest in buoyancy driven flows and incorporates the possibility of systematically designing initial and boundary conditions for passive control of late time turbulence. On the educational front, it will help support two graduate students and will introduce students to cutting edge research ideas in a graduate level course on Turbulent Flows. Undergraduate researchers will be included through the Missouri S&T-OURE (Opportunities for Undergraduate Research Experience) program. The students who will perform the bulk of this research will be actively recruited from underrepresented groups (women and minority) at Missouri S&T through the Women in Science & Engineering (WISE) program on campus. In addition, active collaboration with Los Alamos National Laboratory (LANL) will aid in the potential impact of this work and is expected to result in future research opportunities for graduate students upon completion of their degrees.