A Multiscale Approach to Disperse Two-phase Flow

建议编号：0625138主要研究员：普罗斯佩莱蒂，安德烈附属：约翰霍普金斯大学命题：一种分散两相流的多尺度方法智力优点：这项工作是首次将多尺度计算应用于分散多相流问题。它的目标是发展一种方法，将流体流动和悬浮颗粒的详细局部数值解耦合到基于平均方程的粗粒度描述。具体目的是研究边界固体壁面对分散流体颗粒流动的影响。虽然用平均方程来处理这类流动已经取得了很大的进展，但对这些方程的求解施加适当的边界条件并不是很好。为了解决这一问题，建议进行多尺度模拟，其中壁面区域将通过直接数值模拟来处理，该数值模拟将精确地求解具有悬浮有限尺寸颗粒的N-S方程。这个详细的模型将与一个平均方程模型相耦合，该模型描述了远离墙的区域中的流动。除了边界条件问题的具体结果外，预计准确和有效地解决在两种描述的耦合中出现的许多问题将为多尺度计算在多相流中的其他应用开辟道路。由于计算的局限性，以前的绝大多数模拟都是在极小的粒子浓度条件下将粒子近似为质点进行的。有许多非常重要的情况是不能用这些方法来研究的：悬浮在液体中的颗粒、非稀释体系和许多其他情况。这里使用的算法能够充分考虑颗粒的有限范围，并能够模拟稠密系统。广泛影响：多相流是当代研究的一个非常重要的领域。对这项研究感兴趣有令人信服的科学理由：对这类问题的统计处理既是必要的，也是具有挑战性的；流体力学整个学科的很大一部分是相关的；基本过程，如聚集和扩散，还没有完全理解。多尺度计算技术的成功发展将对该学科的进步产生重大影响。在这一领域接受培训的年轻研究人员将能够加入一个充满活力的科学社区，解决重要的研究目标。

ABSTRACTProposal Number: 0625138Principal Investigator: Prosperetti, AndreiAffiliation: Johns Hopkins UniversityProposal Title: A multi-scale approach to disperse two-phase flowIntellectual Merit:This work is the first application of multiscale computing to a disperse multiphase flow problem. Its objectives are to develop methods to couple detailed local numerical solutions of fluid flow with suspended particles to a coarse-grained description based on averaged equations. The specific objective is to study the effect of the bounding solid walls on a disperse fluid particle flow. While much progress has been made in the treatment of such flows by means of averaged equations, the proper boundary conditions to be imposed on the solution of these equations are not well established. In order to address this problem, it is proposed to conduct a multiscale simulation in which the wall region will be treated by direct numerical simulation accurately solving the Navier-Stokes equations with suspended finite-sized particles. This detailed model will be coupled to an averaged-equations model describing the flow in the regions away from the walls. Beyond the specific results for the boundary conditions problem, it is expected that an accurate and efficient solution of the many issues that arise in the coupling of the two descriptions will open the way to other applications of multiscale computing to multiphase flow. Computational limitations have forced the vast majority of previous simulations to be conducted by approximating the particles as mass points in conditions of exceedingly small particle concentration. There are many very important situations which cannot be studied by these means: particles suspended in a liquid, non-dilute systems and many others. The algorithm to be used here is capable of taking full account of the finite extent of the particles and to simulate dense systems.Broader Impacts:Multiphase flow is a very vital area of contemporary research. There are compelling scientific reasons for the interest in this research: the statistical treatment of problems of this type is as necessary as it is challenging; a large fraction of the entire discipline of Fluid Mechanics is relevant; and fundamental processes, such as clustering and diffusion are incompletely understood. The successful development of multiscale computational techniques will have a significant impact on the progress of the discipline. Young researchers trained in this field will be able to join a vibrant scientific community addressing significant research objectives.