Characterization of Turbulent Flow in Porous Media: Integrating Experiments, DNS, and Theory

1336983 wood本研究的主要目的是研究多孔介质中的快速（高雷诺数）流动。提出了一种整合三个研究要素的统一方法：(1)带闭合的上尺度理论（体积平均法）；(2)多孔介质流动的直接数值模拟（DNS）；(3)多孔介质流动的PIV实验研究。该研究将涵盖广泛的雷诺数范围[Re ~O(100-4000)]。这项工作的总体目标是提供一个内聚理论（经过广泛的实验验证），以一种与被广泛使用的经验表达式达西-厄根-福奇海默方程相一致的方式来描述充填床中相当高的流速。高回流在多孔介质中的广泛应用包括固定床反应器、核反应器和地下地下水修复中的气体吸附、过滤、催化剂反应、燃烧、热输运等过程。由于孔隙空间内复杂而不规则的流动几何形状、流动的限制方面以及可变的长度尺度，很难正确定义多孔材料中高回流的平均流动结构和相关湍流。这些复杂性使得实验观察和数值模拟极其困难。迄今为止，关于随机填充多孔介质中湍流流动的详细PIV或DNS数据很少，也没有DNS和实验交叉验证的数据。拟议的研究汇集了独特的和互补的专业知识和能力，在实验，计算和理论方法。结合实验和模拟数据，将增强我们对多孔材料流动物理的理解。升级方法将专注于提供一致的理论，有可能改变致密多孔介质中热量或标量传输的建模方法。实验将使用三分量时间分辨粒子图像测速法对简单立方填充和随机填充的多孔微珠进行孔隙尺度速度场数据分析。DNS的工作将集中在高保真度，完全解决的稳定/非稳定惯性，过渡和湍流的直接数值模拟。这两个来源的详细数据将阐明复杂的流动结构和湍流特性，为开发多孔介质宏观流动和输运特性预测工具奠定理论基础。具体来说，这些数据将有助于直接评估由于模型中未解决的子网格运动尺度而导致的非线性封闭项。研究计划将成为训练学生的基础，并帮助他们认识到对复杂问题进行综合分析的必要性。在实验室里，pi一直有让代表性不足的群体参与进来的记录，包括研究生和本科生（比如德事力学者（Textronic Scholars，面向一年级女生）和大学荣誉学生）。这个项目将接触到发展中的工程师，通过俄勒冈州立大学微笑指导计划为中学生提供学习机会（该计划针对代表性不足的群体）。通过与图卢兹流体力学研究所的合作，学生也将获得国际曝光机会。此外，研究生将通过拟议拨款和部门资金支持，在国际和国内会议上展示他们的工作。研究人员将在最后一年计划在国际会议（如AGU）上举行两次特别会议。该项目由流体动力学和化学、生物工程、环境和运输系统部门的颗粒和多相过程项目共同资助。

1336983WoodThe primary objective of the proposed research is to examine fast (high Reynolds number) flows in porous media. A unified approach is proposed, which integrates three research elements (1) upscaling theory (the method of volume-averaging ) with closure, (2) direct numerical simulation (DNS) of flow in porous media, and (3) PIV experimental studies of flows in porous media. The study will cover a broad range of Reynolds numbers [Re ~O(100-4000)]. The overall goal of this work is to provide a cohesive theory (with extensive experimental validation) to describe rather high velocity flows in a packed bed in a way that is consistent with the widely-used empirical expression known as the Darcy-Ergun-Forchheimer equation. The wide range of applications of high Re flows in porous media includes gas adsorption, filtration, catalyst reactions, combustion, heat transport and other processes in fixed bed reactors, nuclear reactors and subsurface groundwater remediation. Due to the complex and irregular flow geometry within the pore space, the confining aspects of the flow, and the variable length scales, it is difficult to properly define the mean flow structure and associated turbulence of high Re flows in porous materials. These same complexities make experimental observations and numerical simulations extremely difficult. To date there exist few detailed PIV or DNS data for turbulent flows in randomly packed porous media, and none that cross validate among DNS and experiment. The proposed research brings together unique and complementary expertise and capabilities in experimental, computational, and theoretical approaches. Combined experiments and simulation data will be used to enhance our understanding of the flow physics in porous materials. The upscaling approach, which will focus on providing a consistent theory, has the potential to transform modeling approaches for heat or scalar transport in densely packed porous media. The experiments will involve pore-scale velocity field data for both simple cubic packing and randomly packed porous beads using three-component time-resolved particle image velocimetry. The DNS work will focus on high-fidelity, fully resolved direct numerical simulations of steady/unsteady inertial, transitional and turbulent flows. The detailed data from both sources will elucidate the complex flow structures and turbulence characteristics needed to form a theoretical basis for the development of a predictive tool for macroscopic flow and transport properties in porous media. Specifically, the data will facilitate direct evaluation of non-linear, closure terms due to unresolved, sub-grid scales of motion in the model.The research plan will become the basis for training students and helping them appreciate the need for the integrated analysis necessary for complex problems. The PIs have a track record of involving underrepresented groups in their laboratories, both graduate and undergraduates (such as Textronic Scholars [available to first-year women] and University Honors Students. This project will reach out to developing engineers to provide a learning opportunity through the OSU-SMILE mentoring program for middle school students (which targets underrepresented groups). International exposure through collaborations with Insitut de Mecanique des Fluides de Toulouse will also be available to students. In addition the graduate students will be supported through the proposed grant and departmental funds to present their work at international and national conferences. The investigators will plan two special sessions at international conferences (such as AGU) during the final year.This project is jointly funded by the Fluid Dynamics and Particulate and Multiphase Processes Programs in Chemical, Bioengineering, Environmental, and Transport Systems Division.