Suspensions and Granular Media: Wet vs. Dry

CBET-0828563 BradyProject摘要智能优点：悬浮液和颗粒介质广泛存在于自然界和工业中。虽然这两个领域是独立发展的，但最近人们注意到，粘性悬浮液和干燥的颗粒状物质经常表现出相似的流动现象。尽管有相似之处，但这两个领域仍然是分开的。在这里，我们认为这种分离是不必要的，悬浮液和颗粒介质--湿的和干的--实际上对应于一个共同系统的不同限制行为。连接参数是Stokes数，即惯性与剪力之比：小的Stokes数对应于粘性悬浮液，高的Stokes数对应于干燥的颗粒介质。所提出的研究是一项覆盖整个斯托克斯数(和浓度)范围的模拟研究，从而探索了这两个场之间的流动行为和流变学联系。我们不仅将了解这种联系，还可能增进我们对悬浮和颗粒状媒体的理解。这项研究还提供了重要的流变学数据(剪切应力和法向应力、剪切引起的扩散系数、微观结构等)。对于惯性悬浮，似乎出人意料地微乎其微。更广泛的影响：在更广泛的背景下，这项研究将有助于阐明一种通常被称为物质的新状态-颗粒物质的行为。颗粒流是更大的多相流区域的一部分，应用范围从河流和海湾的泥沙输送，到矿物的气力输送，再到药粉的生产。这项工作还将吸引博士生，他们将成为计算方法、多相流体物理和流变学方面的专家。该研究为多相流模型的建立奠定了基础，多相流模型在科学技术中有着广泛的应用。

CBET-0828563BradyProject SummaryIntellectual Merit: Suspensions and granular media are found widely in nature and industry. And although the two fields have developed independently, recently it has been noted that viscous suspensions and dry granular materials often display similar flow phenomena. Despite the similarities, the two fields nevertheless remain separate. Here we propose that this separation is unnecessary and that suspensions and granular media - wet and dry - actually correspond to different limiting behaviors of one common system. The linking parameter is the Stokes number - the ratio of the inertial to shear forces: small Stokes numbers correspond to viscous suspensions and high Stokes numbers to dry granular media. The proposed research is a simulation study covering the entire range of Stokes numbers (and concentrations) and thus explores the flow behavior and rheological connection between these two fields. Not only will we learn about this connection, we may also advance our understanding of both suspensions and granular media. This study also provides vital rheological data (shear and normal stresses, shear-induced diffusivities, microstructures, etc.) for inertial suspensions, of which there appears to be surprisingly little.Broader Impact: In a broader context, this research will help elucidate the behavior of an often called new state of matter - granular matter. Granular flow forms part of the larger area of multiphase flow with applications ranging from sediment transport in rivers and bays, to pneumatic conveying of minerals, to the production of pharmaceutical powders. The work will also engage PhD students who will become experts in computational methods, multiphase fluid physics and rheology. This research provides the foundation for modeling multiphase flows that has widespread application in science and technology.