Improving Statistical Convergence in Direct Numerical Simulations by Exploring Large-Scale Structures Organization and Symmetry

通过探索大规模结构组织和对称性来提高直接数值模拟中的统计收敛性

基本信息

批准号：
1707075
负责人：
Yulia Peet
金额：
$ 33.12万
依托单位：
Arizona State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-09-01 至 2021-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1707075&HistoricalAwards=false
关键词：
Improving Statistical Convergence Direct Numerical

项目摘要

Computational Fluid Dynamics (CFD) is used to describe, explain, and predict turbulent fluid flow externally around airplanes, rockets, and ground vehicles and internally in engines and building ventilation systems. Such computations can be expensive because of the unsteady structures in the turbulence. This project will focus on developing simulation techniques to make such computations more practical. Outreach activities through ASU community-connect infrastructure will focus on educating high-school students about turbulence and its connection to real-life applications through short tutorials and demonstrations involving advanced visualization of turbulent flows and large-scale organized motions. The goal of this project is to develop the strategies that mitigate the problem associated with the persistence of slow moving coherent structures in certain portions of the flow domain, or locking, during the finite time of numerical simulations. In these situations, the collected flow statistics can be significantly biased by the localized and temporary effect of these structures and cannot reliably represent a long-term system dynamics. The current proposal is devoted to designing simple but efficient strategies that will yield significantly improved convergence of statistics in numerical simulations over a much reduced computational time. These strategies include efficient sampling over multiple realizations and multiple states of the flow during the finite time of the simulations. This will be achieved by designing specific mathematical transformations of the computed flow field at a runtime that can be thought of as disturbances that trigger the state transitions in nature. The symmetries of the system will be explored to design the transformations that (i) amenable to promoting quick transitions into desired unsampled flow states, (ii) mathematically consistent and preserve the governing fluid dynamics equations. In addition to improving statistical convergence, the project seeks to answer the following scientific questions: (i) whether the observation of very long-lived asymmetric flow states in certain symmetric systems, such as jets in crossflow and bluff-body wakes, is an artifact of a similar phenomenon of coherent structure locking and whether the current techniques will yield symmetric average fields, (ii) whether addition of the samples from the newly reconstructed states improve a long-term prediction of the system dynamics by low-order models, such as Proper Orthogonal Decomposition. The research is coupled to the educational plan that includes outreach activities at local Phoenix district high schools, involvement of undergraduates in research, and improving graduate curriculum.

计算流体动力学 (CFD) 用于描述、解释和预测飞机、火箭和地面车辆外部以及发动机和建筑通风系统内部的湍流流体流动。由于湍流中的结构不稳定，这种计算可能会很昂贵。该项目将重点开发模拟技术，使此类计算更加实用。通过亚利桑那州立大学社区连接基础设施开展的外展活动将侧重于通过简短的教程和演示，对高中生进行湍流及其与现实生活应用的联系的教育，涉及湍流的高级可视化和大规模有组织的运动。该项目的目标是制定策略，缓解在数值模拟的有限时间内，与流域某些部分中缓慢移动的相干结构的持久性或锁定相关的问题。在这些情况下，收集到的流量统计数据可能会因这些结构的局部和临时影响而产生显着偏差，并且不能可靠地代表长期的系统动态。当前的提案致力于设计简单但有效的策略，这些策略将在大大减少计算时间的情况下显着提高数值模拟中统计的收敛性。这些策略包括在有限的模拟时间内对流的多个实现和多个状态进行有效采样。这将通过在运行时设计计算流场的特定数学变换来实现，该变换可以被认为是触发自然界状态转换的扰动。将探索系统的对称性来设计变换，(i) 能够促进快速过渡到所需的未采样流动状态，(ii) 数学上一致并保留控制流体动力学方程。除了提高统计收敛性之外，该项目还试图回答以下科学问题：（i）在某些对称系统中观察到的非常长寿命的不对称流动状态（例如横流中的射流和钝体尾流）是否是一种人为现象相干结构锁定的类似现象以及当前技术是否会产生对称平均场，（ii）添加新重建状态的样本是否可以改善低阶模型对系统动力学的长期预测，例如真正交分解。该研究与教育计划相结合，其中包括凤凰城当地高中的外展活动、本科生参与研究以及改进研究生课程。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Cost vs Accuracy: DNS of turbulent flow over a sphere using structured immersed-boundary, unstructured finite-volume, and spectral-element methods

成本与精度：使用结构化浸入边界、非结构化有限体积和谱元方法对球体上的湍流进行 DNS 分析

DOI：
10.1016/j.euromechflu.2023.07.008
发表时间：
2023-11
期刊：
European Journal of Mechanics - B/Fluids
影响因子：
0
作者：
Capuano, Francesco;Beratlis, Nikolaos;Zhang, Fengrui;Peet, Yulia;Squires, Kyle;Balaras, Elias
通讯作者：
Balaras, Elias

Verification and convergence study of a spectral-element numerical methodology for fluid-structure interaction

流固耦合谱元数值方法的验证和收敛性研究