Visiting Researcher: BiGlobal Methods for Optimal Flow Perturbations

客座研究员：最优流动扰动的 BiGlobal 方法

基本信息

批准号：
EP/E006493/1
负责人：
Spencer Sherwin
金额：
$ 4.12万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2006
资助国家：
英国
起止时间：
2006 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FE006493%2F1
关键词：
Visiting Researcher BiGlobal Methods Optimal

项目摘要

Research applications of computational fluid dynamics in viscous, unsteady and separated flows since the mid-1980s largely focused on direct simulation of the time-dependent Navier--Stokes equations. Increases in computational power and advances in computational methods over this time have permitted significantly larger simulations to be performed, with concomitantly larger volumes of data as the outcome. However one of the major issues still facing the analyst, particularly when dealing with unsteady and transitional/turbulent simulations, is the question of how to assimilate, analyse and apply this great wealth of data. The development complex geometry stability (biglobal) and bifurcation analyses to understand the dominant instability modes of the underlying basic state have provided a powerful tools to applying computational analysis which complement experimental data.Despite the successes of biglobal stability methods in complex geometries in various application such as bluff body flows there have still been a number significant failures of this classical approach, e.g. the finding that both tubular Poiseuille flow and planar Couette flow are asymptotically linearly stable (whereas they are both well-known to support turbulence). More recently, there has been a general recognition of the fundamental importance of non-normality of linear instability modes and techniques using adjoint methods to determine optimal flow perturbations. However the published works dealing with applications of regular and adjoint modes have almost without exception dealt with either one-dimensional or quasi-one-dimensional boundary-layer type flows, while biglobal stability analyses have dealt only with with the asymptotic instability of regular modes. In the present proposal, we seek to begin the process of marrying the methods, by extending our existing highly accurate spectral/$hp$ element stability analysis for asymptotic instabilities to the problem of optimal growth, but in general geometries.The researchers believe significant further progress will only be possible through continued direct collaboration. A certain amount of useful interchange and incremental advance can take place through email exchanges, but for rapid progress and significant advances this cannot replace face-to-face interaction. This application therefore seeks funding to allow an external visit to the UK by Dr~Blackburn in 2006. During this visit Blackburn, Sherwin and Barkley will build on existing research and consolidate further work which will be undertaken in the intervening period.

自1980年代中期以来，计算流体动力学在粘性，不稳定和分离的流中的研究应用很大程度上集中在直接模拟时代依赖性的Navier（Stokes）方程。在这段时间内，计算能力的增加和计算方法的进步已允许进行更大的模拟，并随之而来的数据量大多是结果。但是，仍面临分析师的主要问题之一，尤其是在处理不稳定和过渡/动荡的模拟时，如何同化，分析和运用这些大量数据。开发复杂的几何稳定性（Biglobal）和分叉分析，以了解基本基本状态的主要不稳定性模式为应用计算分析提供了强大的工具，这些工具可以补充实验数据。尽管在各种应用中，大斑bal稳定性方法的成功，例如在各种应用中，例如Bluff体流中的复杂地理位置上的成功率，但仍具有这种典型的失败。管状Poiseuille流量和平面couette流的发现在线性稳定上都是渐近的（而它们都是众所周知的支持湍流）。最近，人们普遍认识到使用伴随方法来确定最佳流动扰动的线性不稳定模式和技术的基本重要性。但是，与常规和伴随模式的应用有关的已发表的作品几乎没有例外处理一维或准二维边界层型流，而Biglobal稳定性分析仅处理了常规模式的渐变不稳定性。在本提案中，我们试图通过扩展现有的高度准确的光谱/$ HP $元素稳定性分析，以实现渐近不稳定性到最佳增长问题，但是一般的几何形状，研究人员认为，只有通过直接的直接合作才有可能进一步的进一步进展，我们试图开始结婚的过程。可以通过电子邮件交流进行一定数量的有用的互换和增量进步，但是为了快速进步和重大进展，这不能取代面对面的互动。因此，该申请寻求资金，以允许〜Blackburn博士于2006年对英国进行外部访问。在这次访问中，布莱克本，舍温和巴克利将在现有研究的基础上进行，并巩固将在此期间进行的进一步工作。