Investigating turbulent particulate flows with the aid of invariant solutions to the Navier-Stokes equations

借助纳维-斯托克斯方程的不变解研究湍流颗粒流

• 批准号: 511929279
• 负责人: Professor Dr. Markus Uhlmann
• 金额: --
• 依托单位: Institut für Hydromechanik (IfH)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/511929279?language=en
• 关键词: Investigating; turbulent; particulate; flows; aid

Many natural and man-made fluidic systems feature a disperse particulate phase, and the majority of these flows is turbulent. Examples are hydro-meteors (rain, snow or hail) in the earth's atmosphere, sediment particles in surface water bodies, or the solid matter transported through an industrial pipeline system. Despite much past research effort our understanding of turbulent particulate flows is still rather limited at this point due to two factors. First, obtaining high-fidelity data in such multi-phase flow systems still poses a formidable challenge to modern experimental and numerical techniques. Second, high-quality data-sets feature an enormous number of degrees of freedom, and they are therefore extremely tedious to analyze. The situation is even worse in the case of particles with a size larger than the smallest relevant flow scales, since they are fully coupled to the fluid motion and no simplified description for their dynamics is available. Here we propose to reduce the complexity of the systems by replacing fully developed turbulence in the carrier phase with one of the relevant invariant solutions (i.e. travelling waves or periodic orbits) pertaining to the specific flow configuration. Our strategy follows the spirit of the dynamical systems approach to turbulence, which considers that invariant solutions contain most of the essential information and thereby form the skeleton of turbulence. Analyzing the dynamics of solid particles in these simpler flows is then much less resource-intensive (thereby allowing for extensive parameter sweeps), while the results can still be directly related to fully-developed turbulence. Our working hypothesis is that carrying out this program will allow us to shed new light on long-standing open questions such as the influence of turbulence upon the settling velocity and the clustering of finite-size particles.

许多天然和人造的流体系统以分散的颗粒相为特征，并且这些流动的大部分是湍流。例如，地球大气中的水流星(雨、雪或冰雹)，地表水体中的沉积物颗粒，或通过工业管道系统运输的固体物质。尽管过去做了大量的研究工作，但由于两个因素，目前我们对湍流颗粒流的了解仍然相当有限。首先，在这样的多相流系统中获得高保真数据仍然是对现代实验和数值技术的巨大挑战。其次，高质量的数据集具有巨大的自由度，因此分析它们非常繁琐。对于尺寸大于最小相关流动尺度的颗粒，情况甚至更糟，因为它们与流体运动完全耦合，并且没有对其动力学的简化描述。在这里，我们建议通过用与特定流动构型相关的不变解(即行波或周期轨道)之一来替换载流相中的完全发展的湍流来降低系统的复杂性。我们的策略遵循了动力系统方法研究湍流的精神，该方法认为不变解包含了大多数基本信息，从而形成了湍流的骨架。在这些更简单的流动中分析固体颗粒的动力学则不那么耗费资源(从而允许广泛的参数扫描)，而结果仍然可以与充分发展的湍流直接相关。我们的工作假设是，执行这一计划将使我们能够为长期悬而未决的问题提供新的线索，例如湍流对沉降速度的影响和有限大小颗粒的聚集。