Numerical study of high-Reynolds number vortex flows with high-order accurate meshless vortex method.

高阶精确无网格涡流法对高雷诺数涡流的数值研究

基本信息

批准号：
EP/E033083/1
负责人：
Lorena Barba
金额：
$ 26.66万
依托单位：
University of Bristol
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE033083%2F1
关键词：
Numerical study Reynolds number vortex

项目摘要

The flow of fluids is an unusually difficult subject to study, but it affects innumerable aspects of our life. The understanding of the flow of blood in the heart, the vortices created by jet airliners, the cooling of a laptop's microchip, and the flow of air in the atmosphere and water in the ocean, all of these require knowledge of fluid dynamics. Fluid dynamics is a very challenging and exciting field of science. The applications are countless, and so are the complexities. Because the general physical description of fluids results in a mathematical formulation --a differential equation-- which cannot in general be solved, scientists have attempted to use computer simulations since these were available. In fact, many advances in computational science are a direct result of the efforts to tackle some problem of fluid flow.Some flows are particularly difficult to solve, even with the most powerful computers. Flows involving eddies of multiple sizes, turbulence or rapid changes are the chief example. But vortices appear almost everywhere in fluids, and they are responsible for many phenomena that we would like to understand or control. For example, when we hear the noise of a helicopter, that noise is in great measure produced by the vortices left behind by one blade being hit by the next oncoming blade. And when airplanes are spaced by the control tower on approach to landing, it is mostly due to the need to avoid the vortices left behind by the previous plane landing. If our understanding of airplane vortices was such that we could predict where they are in a given moment, the instructions for the next oncoming plane could be safely given with airport efficiency in mind. A huge amount of money could be saved by increasing the frequency of landings in this way.To study these types of problems, the computational approach is essential. The field of Computational Fluid Dynamics involves computer simulations of problems of fluid flow. In this field, the majority of scientists use methods which are based on dividing the space where there is fluid into small elements, squares or triangles, or cubes, where the equations are said to be discretised. The equations are solved by, for example, keeping track of how much fluid enters one side, and leaves the other side, of the elements. These methods have been used for decades, and can produce excellent results. But many times they suffer from one problem: they diffuse the vortices too fast. Using again the example of the jet airliner, they would predict that the wake vortices are gone, when in fact they still persist and pose a danger to oncoming airplanes.Some computational scientists have been experimenting with different methods, where instead of using geometrical elements of fluid, a set of disconnected points are used to calculate the quantities of interest, like velocity. This field has come to be known as meshless or gridfree computation. The research of Dr Barba concentrates in this field, where the use of points, or fluid particles, results in calculations which are able to resolve the small eddies in the flows, and do not diffuse them too fast. The methods are in constant development, and recent advances mean that there is opportunity for very accurate simulations. The research programme of Barba aims to develop an advanced method, based on vortex particles, which is highly accurate. She will introduce innovations allowing the calculation of a range of scales in the flow, more efficiently, and develop clever ways of accounting for the presence of bodies immersed in the fluid. These advances promise to have a significant impact in the field of meshless computation. Moreover, she will use the new methods to study specific problems of interest to physical oceanographers and aerodynamicists, involving interaction of vortices. The results of this research will make progress in both vortex dynamics and computational science in general.

流体的流动是一个异常难以研究的课题，但它影响着我们生活的无数方面。了解心脏中的血液流动、喷气式客机产生的涡流、笔记本电脑微芯片的冷却以及大气中空气和海洋中水的流动，所有这些都需要流体动力学知识。流体动力学是一个非常具有挑战性和令人兴奋的科学领域。应用程序数不胜数，复杂性也数不胜数。由于流体的一般物理描述会产生数学公式（微分方程），而该数学公式通常无法求解，因此科学家们尝试使用计算机模拟，因为计算机模拟已经可用。事实上，计算科学的许多进步都是解决流体流动问题的直接结果。即使使用最强大的计算机，有些流动也特别难以解决。涉及多种尺寸的涡流、湍流或快速变化的流动是主要的例子。但涡旋几乎出现在流体中的任何地方，它们造成了我们想要理解或控制的许多现象。例如，当我们听到直升机的噪音时，这种噪音很大程度上是由一个叶片被下一个迎面而来的叶片撞击时留下的涡流产生的。当飞机在着陆时被控制塔拉开距离，主要是为了避免前一次飞机着陆时留下的涡流。如果我们对飞机涡流的理解能够预测它们在给定时刻的位置，那么就可以在考虑机场效率的情况下安全地给出下一架迎面而来的飞机的指示。通过这种方式增加着陆频率可以节省大量资金。要研究此类问题，计算方法至关重要。计算流体动力学领域涉及流体流动问题的计算机模拟。在这一领域，大多数科学家使用的方法是将有流体的空间划分为小元素、正方形、三角形或立方体，其中方程被离散化。例如，通过跟踪有多少流体进入元件的一侧并离开元件的另一侧来求解方程。这些方法已经使用了几十年，并且可以产生出色的结果。但很多时候它们都会遇到一个问题：漩涡扩散得太快。再次以喷气式客机为例，他们预测尾流涡流已经消失，但事实上它们仍然存在，并对迎面而来的飞机构成危险。一些计算科学家一直在尝试不同的方法，而不是使用几何元素流体，一组断开的点用于计算感兴趣的量，例如速度。该领域被称为无网格或无网格计算。巴尔巴博士的研究集中在这一领域，其中使用点或流体粒子进行计算，能够解决流动中的小涡流，并且不会使它们扩散得太快。这些方法正在不断发展，最近的进展意味着有机会进行非常准确的模拟。 Barba 的研究计划旨在开发一种基于涡流粒子的高精度先进方法。她将引入创新技术，允许更有效地计算流动中的一系列尺度，并开发巧妙的方法来解释浸入流体中的身体的存在。这些进步有望对无网格计算领域产生重大影响。此外，她将利用新方法研究物理海洋学家和空气动力学家感兴趣的具体问题，包括涡旋相互作用。这项研究的结果将在涡动力学和计算科学方面取得总体进展。