U.S.-Austria Cooperative Research on the Hydrodynamic Stability of a Resuspended Layer

该奖项支持该市的Andreas Acrivos教授 纽约学院与Uwe教授合作 流体动力学和热研究所的Schaflinger 转让，维也纳技术大学，在一项研究， 再悬浮层的流体动力学稳定性。 几 Acrivos博士的研究生和博士后同事 将参与该项目。 最近有人 在层流条件下， 固体颗粒的沉降床由于作用而再悬浮 剪。 进一步的实验表明， 在再悬浮层和透明流体之间 由于界面波而不稳定。 建议的目的 合作研究是将数字计算联合收割机 通过精心指导的实验，以验证 从空间到空间的过渡的理论预测 绝对不稳定的流动，并深入了解 负责建立和分裂的机制 海浪 这项研究将使用一个实验装置， 由Schaflinger博士建造用来研究基本的再悬浮流 在二维通道中。 他和他在维也纳的团队 非常有经验的实验技术，分析和 数值方法在流体动力学，特别是在两个 相流 与此同时，国际 在纽约州委员会工作组在下列领域的公认专门知识： 剪切诱导颗粒迁移，流体动力学稳定性 和流变学。 他们正在进行的理论研究 粘性再悬浮将大大增强， 实验合作。 再悬浮作用在大多数沉积物中起着重要作用 运输现象，包括工业问题， 错流微滤 在什么条件下 负浮力颗粒的沉降层将重新悬浮 并不容易理解，通常与 高雷诺数下的湍流。 再悬浮也可以 发生在低雷诺数时，惯性效应 不明显，流动是层流。 该项目将 产生一个系统的研究不稳定性， 通过调节两个叠加分层流体的界面 根据正在进行的流程参数 分析和数值研究在CCNY。 应当 导致粘性再悬浮的基本见解， 多相流的稳定性。

This award supports Professor Andreas Acrivos of the City College of New York to collaborate with Professor Uwe Schaflinger of the Institute of Fluid Dynamics and Heat Transfer, Technical University of Vienna, in a study of the hydrodynamic stability of a resuspended layer. Several graduate students and postdoctoral associates of Dr. Acrivos will participate in the project. It has recently been established that under laminar conditions an initially settled bed of solid particles is resuspended due to action of shear. Further experiments have shown that the interface between the resuspended layer and the clear fluid becomes unstable due to interfacial waves. The aim of the proposed cooperative research is to combine numerical calculations with carefully directed experiments in order to verify the theoretical prediction of a transition from a spatially to an absolutely unstable flow and to gain insight into the mechanisms responsible for the creation and the breakup of the waves. The research will use an experimental setup designed and built by Dr. Schaflinger to study the basic resuspension flow in a two dimensional channel. He and his group in Vienna are very experienced with experimental techniques, analytical and numerical methods in fluid dynamics and specifically in two phase flows. Complementing this is the internationally recognized expertise of the group at CCNY in the fields of shear induced migration of particles, hydrodynamic stability and rheology. Their ongoing theoretical investigation of viscous resuspension will be greatly enhanced by this experimental collaboration. Resuspension plays an important role in most sediment transport phenomena, including industrial problems such as cross flow microfiltration. The conditions under which a settled layer of negatively buoyant particles will resuspend are not well understood and are usually associated with turbulence at high Reynolds numbers. Resuspension can also occur at low Reynolds numbers for which inertial effects are insignificant and the flow is laminar. This project will produce a systematic study of the instabilities at the interface of two superposed stratified fluids by adjusting the parameters of the flow in accordance with the ongoing analytical and numerical investigations at CCNY. It should result in fundamental insights into viscous resuspension and the stability of multiphase flows.