Suspensions and Granular Media: Wet vs. Dry

智力优势：悬浮液和颗粒状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颗粒材料经常表现出类似的流动现象。尽管有相似之处，但这两个领域仍然是分开的。在这里，我们提出这种分离是不必要的，悬浮液和颗粒介质-湿和干-实际上对应于一个共同系统的不同极限行为。链接参数是斯托克斯数——惯性力与剪力的比值：小的斯托克斯数对应于粘性悬浮液，大的斯托克斯数对应于干燥的颗粒状介质。该研究是一项模拟研究，涵盖了整个斯托克斯数（和浓度）范围，从而探索了这两个领域之间的流动行为和流变联系。我们不仅可以了解这种联系，还可以提高我们对悬浮液和颗粒介质的理解。该研究还为惯性悬架提供了重要的流变数据（剪切和正应力，剪切诱导扩散率，微观结构等），其中似乎很少。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。颗粒流是多相流的一部分，其应用范围从河流和海湾中的沉积物输送，到矿物的气动输送，再到制药粉末的生产。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。该研究为多相流的建模提供了基础，在科学技术上具有广泛的应用。

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.