Intruder dynamics in fluid saturated granular medium

由固体颗粒和流体组成的介质出现在地质学、石油开采、化学和食品加工工业中。 入侵者在这些情况下的运动，例如，章鱼在海床上挖洞或移动，目前很难预测。 无论入侵者是一个比固体颗粒密度更大的刚性物体，还是一个活跃的物体，如机器人或蠕虫，都是如此。 这项研究将开发一套模型，预测入侵者的详细运动作为其物理特性和介质的函数。此外，实验将进行三维成像技术，允许入侵者的运动和周围的颗粒和流体的运动的同时测量。实验和模型将首先集中在球形入侵者，然后扩展到杆和多连杆机器人入侵者。 这些机器人可能用于探测海洋沉积物，其设计规则将通过研究淡水蠕虫的运动来制定。最终，研究结果将应用于工业中湿颗粒材料的有效处理，以及可以在复杂环境中移动的机器人的开发。 该项目将提供研究经验，为学生在他们的教育生涯的各个阶段，在一个合作的环境，专注于干。入侵者在干颗粒材料的运动进行了研究，以了解非遍历行为的动力系统和隔离机制。 然而，流体饱和颗粒介质中的入侵者动力学的理解，重要的是更广泛的自然和工业系统，在很大程度上是欠发达。最近开发的介质的流变学描述作为一个功能的无量纲惯性和粘性数从颗粒和悬浮液的研究将结合低雷诺数流体动力学阻力理论来描述入侵者在多相颗粒系统的运动。紧密耦合的荧光标记的内部成像技术将进一步发展和用于测量在单颗粒水平的颗粒和流体相的重排。详细测量的形状和方向相关的阻力的入侵者结合所观察到的阻力的介质的微观力学的连接将使一个基本的流变学模型的主动和被动入侵者的动态通过湿颗粒介质的发展。该项目活动还将支持一系列教育活动，包括促进本科生和研究生的实验室研究经验，以及针对学校学生和公众的外展活动。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Media composed of solid grains and fluids occur in geology, oil recovery, and chemical and food processing industries. The motion of an intruder in these situations, for example, the burrowing or locomotion of an octopus through the sea bed, is currently difficult to predict. This is true whether the intruder is a large, rigid object that is denser than the solid grains or an active object such as a robot or worm. This research will develop a set of models that predict the detailed motion of intruders as a function of their physical properties and those of the medium. In addition, experiments will be performed with three-dimensional imaging techniques that allow simultaneous measurement of the intruder motion and the motion of the surrounding grains and fluid. The experiments and models will focus first on spherical intruders, and then extend to rods and multi-link robot intruders. Design rules for these robots, which might be used to probe marine sediments, will be developed by studying the motion of freshwater worms. Ultimately, the results will be applied to efficient processing of wet granular materials in industry and the development of robots that can move through complex environments. The project will provide research experience for students at various stages of their educational careers in a collaborative environment focused on STEM.Intruder motion in dry granular materials has been studied to understand non-ergodic behavior in dynamical systems and segregation mechanisms. However, an understanding of intruder dynamics in fluid saturated granular medium, important to an even wider range of natural and industrial systems, is largely underdeveloped. Rheological descriptions of the medium developed recently as a function of dimensionless inertial and viscous numbers from granular and suspensions research will be combined with low-Reynolds number hydrodynamic resistive force theory to describe the motion of the intruder in multi-phase particulate systems. Closely coupled fluorescence-tagged internal imaging techniques will be further developed and used to measure the rearrangements of the granular and fluid phase at the single-grain level. Detailed measurement of the shape and orientation dependent drag of the intruder combined with the connection of the observed drag to the micromechanics of the medium will enable the development of a fundamental rheology model of active and passive intruder dynamics through wet granular medium. The project activities will also support a range of educational activities including enabling undergraduate and graduate laboratory research experience, and outreach activities targeting school students and members of the public.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.