Inertial Effects in Porous Media Flows: Experimental and Theoretical Analysis

0933857伍德智力功绩。这一建议侧重于对多孔介质中流动和输运的孔尺度研究，特别强调在雷诺数下的弥散，其中流动中的惯性效应变得重要。我们建议将实验工作、新理论发展和计算相结合，以探索惯性对多孔介质中流动和传输的重要性。多孔介质中的惯性流动在该领域的广泛应用中具有重要意义，从预测填充床反应器的性能到了解地下地下水修复。在这样的应用中，雷诺数通常在惯性范围内，但几乎所有关于多孔介质中流动和输运的理论研究都假设了斯托克斯(非惯性)流。在拟议的研究中，我们计划(I)使用粒子成像测速仪(PIV)在折射率匹配的多孔介质中进行独特的高分辨率三维和三分量速度测量，以确定惯性流对弥散的影响，(Ii)扩展现有理论(通过体积平均)来描述存在惯性流时的渐近和渐近预渐近流动和输运(弥散)，以及(Iii)在亚孔尺度上进行高分辨率计算流体力学模拟流动和输运过程，作为对实验工作的直接证实，并支持放大的理论工作。我们的重点将集中在10Rep 150+范围内的中等(非湍流)粒子雷诺数，但我们也将在非定常层流和湍流区域(Rep 150+)进行更有限的实验和理论研究。假设1.从Darcy流到非线性(Forchheimer Ergan)流的转变可以通过在从Stokes流到惯性流的转变过程中产生复杂的流动结构(螺旋涡、射流、回流区)时产生的动量孔尺度重分布来解释。假设2.在相同雷诺数下，惯性流中流动结构的复杂性将使弥散张量的增加更大。对于色散张量的横向色散分量，这一点最为明显。假设3.随着颗粒雷诺数的增加，色散张量的瞬时演化的影响变得更大(即溶质在有限床中的停留时间相应变短)。这种影响将表现为色散张量对床层位置或床层长度的依赖关系。我们已确定拟议工作将在以下领域产生更广泛的影响：(1)促进发现和理解，同时促进培训和学习；(2)加强网络和伙伴关系；(3)代表人数不足的群体的参与。现将这些要点概括如下。促进培训和学习。我们建议在本科生层面(通过与俄亥俄州立大学NASA本科生微重力飞行团队[MGFT]的现有指导安排)、K-12层面(通过扩大我们与俄亥俄州立大学微笑推广计划的现有互动，并提供视觉流体力学演示，使学生对科学实验测量的力量感到兴奋)和研究生层面(通过安排将一名学生送到太平洋西北国家实验室[PNL]进行夏季研究体验)来促进学习培训。提案的第4.1节对这些教育活动作了更详细的说明。加强网络和伙伴关系。这一建议扩大了PNNL的PIS和研究人员之间的现有合作，并在PIS Wood和Liburdy之间建立了新的跨部门互动。与PNNL的合作很重要，因为(I)PNNL已被证明为研究生提供了极好的机会(如第4.1节所述)，(Ii)PNNL(EMSL)有一个设备齐全的用户设施，过去曾为Pi Wood提供研究设备和专业知识，以及(Iii)该实验室有潜力为我们的学生提供就业机会。提案第4.2节对这些机会作了更详细的说明。代表人数不足的群体的参与。私人投资机构致力于促进多样性，鼓励代表性不足的群体参与。第4.1节所述的K-12教育推广活动在接触任职人数不足的群体，特别是女孩方面非常有效。私人投资机构在鼓励妇女攻读博士学位方面取得了特别成功，这仍将是未来的重点。

0933857WoodIntellectual Merit. This proposal focuses on a pore scale investigation of flow and transport in porous media, with a particular emphasis on dispersion at Reynolds numbers where inertial effects in the flow field become important. We are proposing a combination of experimental work, new theory development, and computation for exploring the importance of inertial contributions to flow and transport in porous media. Inertial flows in porous media have significance in a wide array of applications in the field from predicting the performance of packed bed reactors to understanding subsurface groundwater remediation. In such applications, the Reynolds number is often in the inertial range, but almost all theoretical studies of flow and transport in porous media have assumed Stokes (non-inertial) flow. In the proposed research, we plan to (i) make unique high resolution three dimensional and three component velocity measurements using particle imaging velocimetry (PIV) in index of refraction matched porous media to determine the influence of the inertial flows on dispersion, (ii) extend existing theory (via volume averaging) to describe the asymptotic and pre asymptotic flow and transport (dispersion) when inertial flows are present, and (iii) conduct high-resolution computational fluid dynamics simulations of the flow and transport processes at the sub-pore scale both as direct corroboration of the experimental work, and in support of the upscaling theoretical effort.. Our focus will be on moderate (non turbulent) particle Reynolds numbers in the range 10 Rep 150+, but we will also conduct more limited experimental and theoretical investigations in the unsteady laminar and turbulent flow regimes (Rep 150+). The hypotheses associated with the proposed research are summarized as follows.Hypothesis 1. The transition from Darcy flow to nonlinear (Forchheimer Ergun) flow can be explained by the pore scale redistribution of momentum that occurs when complex flow structures (helical vortexes, jets, regions of back-flow) are generated in the transition from Stokes to inertial flows.Hypothesis 2. The complexity of flow structure during inertial flows will increase the dispersion tensor more than would an equivalent non inertial (Stokes) flow for the same Reynolds number. This will be most evident for the transverse dispersion component of the dispersion tensor.Hypothesis 3. As the particle Reynolds number increases, the influence of the transient evolution of the dispersion tensor becomes greater (in the sense that the residence time of solutes will become correspondingly shorter in a finite bed). This influence will be manifest by the dependence of the dispersion tensor on bed location or bed length.Broader Impacts. We have identified broader impacts that the proposed work will have in the areas of (i) promoting discovery and understanding while promoting training and learning, (ii) enhancing networks and partnerships, and (iii) participation of underrepresented groups. These are summarized as follows. Promoting Training and Learning. We have proposed efforts to promote training in learning at the undergraduate level (through an existing mentoring arrangement with the OSU NASA undergraduate Microgravity Flight Team [MGFT]), K-12 level (by expanding our existing interactions with the OSU SMILE outreach program, and providing visual fluid mechanics demonstrations that excite students to the power of scientific experimental measurements), and graduate level (by arranging to send a student to the Pacific Northwest National Laboratory [PNNL] for a summer research experience). These educational activities are described in greater detail in Section 4.1 of the proposal. Enhancing networks and partnerships. This proposal expands existing collaborations between the PIs and researchers at PNNL, and also establishes a new inter departmental interaction among PIs Wood and Liburdy. The collaboration with PNNL is important because (i) PNNL has proven to provide excellent opportunities for graduate students (as described in Section 4.1), (ii) there is a well equipped user facility at PNNL (EMSL) that has provided research equipment and expertise to PI Wood in the past, and (iii) the lab has the potential to provide employment opportunities to our students. These opportunities are described in additional detail in section 4.2 of the proposal. Participation of Underrepresented Groups. The PIs are committed to promoting diversity and encouraging the participation of underrepresented groups. The K-12 educational outreach described in section 4.1 is very effective at reaching under represented groups, particularly girls. The PIs have had particular success in encouraging women to pursue PhD studies, and this will remain a focus in the future.