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首页> 外文学位 >Computation of unsteady viscous incompressible flow around an obliquely oscillating circular cylinder using a parallelized finite difference algorithm.
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Computation of unsteady viscous incompressible flow around an obliquely oscillating circular cylinder using a parallelized finite difference algorithm.

机译：使用并行有限差分算法计算倾斜振荡圆柱体周围的非稳态粘性不可压缩流。

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摘要

The objective of the thesis is to numerically investigate the near wake structure and fluid forces generated by a circular cylinder oscillating obliquely in a uniform stream of a viscous incompressible fluid. A numerical series expansion solution valid for small values of the time is used to verify the accuracy of the fully numerical scheme in the initial stages of motion. In this latter scheme, the governing Navier-Stokes equations in vorticity-stream function formulation are solved using a parallelized finite difference algorithm which utilizes global conditions of an integral character. A non-inertial coordinate transformation is used to conformally map the unbounded domain outside the cylinder to a rectangular domain which may be discretized by a set of uniformly spaced grid points. Thus, implicitly, the equations are solved on a time-dependent adaptive mesh. The parallel implementation of the algorithm, which is considered for the first time in this thesis, produces nearly optimal speedup results on 8 processors of a Silicon Graphics Onyx shared memory architecture computer. Numerical simulations are conducted at a Reynolds number of R = 200 to first determine fundamental and super-harmonic lock-on ranges. The effect of the amplitude and angle of oscillation on the flow characteristics at several forcing frequencies is then addressed. Whereas inline and transverse oscillations of a circular cylinder have been the focus of many articles, previous work on this problem is limited to a single experimental study by Ongoren and Rockwell (1988b) and three numerical studies by Kocabiyik and Al-Mdallal (2003a,b) and Kocabiyik, Mahfouz, and Al-Mdallal (2004). Therefore, the results of this thesis represent the most comprehensive analysis of the problem to date. Whenever possible, verifications of the method with previous experimental and numerical findings are presented and agreement between the results is excellent.
机译：论文的目的是对粘性流体不可压缩的均匀流中斜向摆动的圆柱体产生的近尾流结构和流体力进行数值研究。一个适用于较小时间值的数值级数展开解可用于验证运动初始阶段全数值方案的准确性。在后一种方案中，使用并行积分有限差分算法（利用积分特征的全局条件）求解涡流函数公式中的主控Navier-Stokes方程。使用非惯性坐标变换将圆柱外部的无界区域保形地映射到矩形区域，该矩形区域可以由一组均匀间隔的网格点离散化。因此，隐式地，方程是在与时间有关的自适应网格上求解的。本文首次考虑该算法的并行实现，可在Silicon Graphics Onyx共享内存体系结构计算机的8个处理器上产生几乎最佳的加速结果。在雷诺数为R = 200的情况下进行数值模拟，首先确定基本和超谐波锁定范围。然后研究了振幅和振荡角度对几个强迫频率下的流动特性的影响。圆柱的轴向和横向振动一直是许多文章的重点，而以前对此问题的研究仅限于Ongoren和Rockwell（1988b）的单个实验研究以及Kocabiyik和Al-Mdallal（2003a，b）的三个数值研究。 ）以及Kocabiyik，Mahfouz和Al-Mdallal（2004年）。因此，本论文的结果代表了迄今为止对该问题的最全面的分析。只要有可能，就用先前的实验和数值结果对方法进行验证，并且结果之间的一致性非常好。

著录项

  • 作者

    Lawrence, Karl P.;

  • 作者单位

    Memorial University of Newfoundland (Canada).;

  • 授予单位 Memorial University of Newfoundland (Canada).;
  • 学科 Engineering Mechanical.
  • 学位 M.Sc.
  • 年度 2004
  • 页码 144 p.
  • 总页数 144
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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