Development and Evaluation of the Unstructured-Grid CFD

本研究旨在对非结构网格计算流体力学进行改进和检验，使其成为流体机械分析和设计的实用工程工具。在为期三年的研究中，获得了以下结果：(1)提出了一种在cad定义模型上生成非结构化曲面网格的新方法。(2)提出了一种隐式时间积分和空间推进求解算法，减少了非结构化网格上流动求解器的计算时间。流动求解器的适用性也扩展到燃烧和不可压缩流动。(3)提出了一种结合流特征检测的解自适应细化方法。该方法在高α三角翼上的有效性得到了验证。(4)提出了一种计算相对运动多体绕流的反置非结构网格方法。(5)将非结构网格CFD应用于机翼、飞机、超短内存喷气发动机、空腔和矩形风道流动等领域，评价了非结构网格CFD的准确性和实用性。这些结果超出了我们的预期。研究过程中提出的新算法已在国际学术会议上得到认可。在此过程中，非结构网格CFD的一些新的研究方向也开始了，如优化。

The present study is to refine and examine the unstructured-grid CFD (computational fluid dynamics) so as to use it as a practical engineering tool for analysis and design of fluid machineries. In the three-year research, the following results were obtained.(1) A new method to generate unstructured surface grid on the CAD-define model was developed. With this method, the pre-processing procedure of the unstructured-grid CFD was significantly simplified(2) An implicit time integration and a space marching solution algorithms were developed to reduce the computational time of the flow solver on unstructured grids. The applicability of the flow solver was also extended to combustion and incompressible flows.(3) A solution-adaptive refinement method coupled with a flow-feature detection was proposed. This method was demonstrated of its effectiveness for the high-alpha delta wings.(4) An overset unstructured grid method was proposed to compute flow around multiple bodies with relative motions.(5) The accuracy and usefulness of the unstructured-grid CFD were evaluated by applying it to wings, airplanes, SCRAM jet engines, cavity and rectangular-duct flows, and so on.These results met more than our expectations. The newly proposed algorithms during the research have already been recognized in the international academic conferences. Several new directions of the unstructured-grid CFD, such as optimization, were also commenced during this research.