Collaborative Research: Drag Rules for Quasi-Static Granlar Media - Experimental and Numerical Studies

摘要提案编号：0626191和0625139主要研究者：Koehler， Stephan和Santamaria， J. carlos隶属于：Emory大学和Georgia Tech研究公司提案标题：合作研究：准静态颗粒介质的阻力规律实验和数值研究智力优势：致密颗粒物质的流动在技术上很重要，但人们知之甚少。相互竞争的致密颗粒物质模型基于不同的物理假设，这些假设有足够的自由参数，可以与实验观察结果大致一致。实验模型系统的数量相对较少，并且它们的典型特征是涉及简单流动的高度对称性，例如平面剪切或库埃特流。为了促进对致密颗粒流的理解，需要考虑更大、更丰富的模型系统。两个研究小组，一个来自埃默里大学物理系，另一个来自佐治亚理工学院土木工程系，将合作研究密集颗粒介质中入侵者的动力学。提出了四个相互关联的项目：1)入侵者在静态颗粒介质中垂直移动的力和流场测量；2)阻力对入侵者方向的依赖；3)由于颗粒物质剪切引起的入侵者阻力变化；4)通过颗粒介质介导的两个入侵者之间的相互作用。埃默里大学的研究小组将进行物理实验；佐治亚理工学院的团队将使用商用的离散单元代码和等效摩擦连续体Cam Clay模型来模拟这四个系统。实验结果将验证代码的准确性，而数值模拟将提供对实验无法达到的量的见解，例如流场和织物。拟议的研究将为入侵者的阻力提供现象学规则，其结果将使理论家能够确定其模型所基于的物理假设的有效性。这些规则对于开发处理颗粒物质的新方法和了解某些沙漠动物如何在沙质环境中游泳具有实际意义。更广泛的影响：将开发程序，以确定基于入侵者阻力的颗粒床内的原位局部流变性。这些程序将在许多不同的设置中加强颗粒物质的处理，从传送带到混合药物粉末。通过将来自两所不同大学和学科的团队结合起来，每个团队研究相同的系统，但使用不同的方法，该项目将建立一个令人兴奋的、协同的和跨学科的环境。这些互动也将促进软凝聚态物理课程和颗粒物质基础课程的跨学科教学。其他活动包括本科生和研究生的研究参与，创建基于网络的教学模块，以及与沙漠生物学家的互动。

ABSTRACTProposal Numbers: 0626191 and 0625139Principal Investigators: Koehler, Stephan and Santamaria, J. CarlosAffiliations: Emory University and Georgia Tech Research CorporationProposal Title: Collaborative Research: Drag Rules for Quasi-Static Granular Media Experimental and Numerical StudiesIntellectual Merit:The flow of dense granular matter is technologically important, but poorly understood. Competing models of dense granular matter are based upon different physical assumptions, that have enough free parameters to allow for general agreement with experimental observations. The number of experimental model systems is relatively small, and they are typically characterized by a high degree of symmetry involving simple flows, such as plane shear or Couette flow. In order to advance understanding of dense granular flow, a larger and richer variety of model systems needs to be considered.Two research teams, one from the Emory physics department and another from the Georgia Tech civil engineering department will collaboratively investigate the dynamics of intruders in dense granular media. Four inter-related projects are proposed: 1) Force and flowfield measurements of intruders moving vertically through static granular media, 2) Dependence of drag forces on the intruder's orientation, 3) Variations of intruder drag forces due to shearing of granular matter, and 4) Interactions between two intruders mediated through the granular medium. The Emory team will perform the physical experiments; the Georgia Tech team will simulate these four systems using a commercially available discrete element code and the equivalent frictional continuum Cam Clay model. The experimental results will verify that the code is accurate, and the numerical simulations will provide insight into experimentally inaccessible quantities, such as the flow fields and fabric. The proposed studies will provide phenomenological rules for the resistive forces on intruders, and the results will enable theorists to determine the validity of physical assumptions upon which their models are based. These rules will be of practical use for developing new methods of handling granular matter and for understanding how certain desert animals swim through sandy environments.Broader Impact:Procedures will be developed for determining the in situ, local rheology within granular beds based upon intruder drag. These procedures will enhance processing of granular matter in many different settings, varying from conveyer belts to mixing of pharmaceutical powders. This program will build an exciting, synergistic and interdisciplinary environment, by combining teams from two different universities and disciplines, with each team studying the same systems but using different approaches. These interactions will also prompt inter-disciplinary teaching of a soft condensed matter physics course and a fundamentals of granular matter course. Additional activities include undergraduate and graduate research participation, creation of web-based teaching modules, and interactions with desert biologists.