Geometry, mesh and adaptivity for high reynolds number viscous flow simulations

虽然数值方法和CFD在过去的二十年里取得了巨大的进步，但它们在高度复杂的工业问题中的适用性仍然受到工程师精确建模和离散计算域所需的努力和时间的限制。拟议的研究旨在通过开发满足模拟需求的创新几何和网格处理方法来帮助减少工程师准备模型所需的时间。该研究项目还旨在提高用于复杂三维机械设备，特别是水力透平机械设计的高雷诺数湍流计算流体动力学(CFD)分析的精确度和精确度。这一建议将探索1)几何建模、2)网格生成和3)后验网格自适应的创新方法，在使用有限体积求解器对粘性、湍流不可压缩流动进行CFD模拟的背景下。提出的几何建模研究旨在提高计算域的表示和操纵能力。本研究将探讨计算域的隐式和标准参数边界表示法的结合，以便从两种表示法在域离散和形状处理方面的互补优势中获益。将通过使用替代表示来构建替代曲面以支持后续的域离散化操作，来特别研究曲面重新参数化技术。网格生成的研究将集中在为高效地生成高质量的计算网格而预先构造适当的单元大小和形状控制函数。在非结构化网格生成过程中，单元形状和大小的控制是工业应用环境中许多困难的来源。建议的研究将旨在确定适用于混合单元类型的网格的有效尺寸指定方法。与后验网格适应相关的主题包括不可压缩湍流Navier-Stokes有限体积解的后验误差估计、控制网格适应算法的若干变量的组合和收敛。

While numerical methods and CFD have progressed tremendously in the last twenty years, their applicability to highly complex industrial problems is still limited by the efforts and time required by engineers to accurately model and discretize computational domains. The proposed research aims to help reduce the time required by engineers to prepare models through the development of innovative geometry and mesh manipulation methods addressing the needs of simulation. This research program also aims to enhance the accuracy and precision of high Reynolds number turbulent computational fluid dynamics (CFD) analysis used for the design of complex three dimensional mechanical devices, and particularly hydraulic turbomachinery. This proposal will investi- gate innovative approaches for 1) geometric modeling, 2) mesh generation and 3) a posteriori mesh adaptation in the context of CFD simulations of viscous, turbulent incompressible flows using finite volume solvers. The proposed research on geometric modeling aims to advance computational domain representation and manipula- tion. This research will investigate combining implicit and standard parametric boundary representation of a computational domain in order to benefit from complementary advantages of each representation for domain discretization and shape manipulation. Surface reparameterization techniques will be particularly investigated, through the construction of surrogate surfaces using alternate representations in support to subsequent domain discretization operations. Research on mesh generation will focus on the a priori construction of adequate el- ement size and shape control functions for the efficient generation of high quality computational grids. Control of element shape and size in the course of unstructured mesh generation is the source of many difficulties in the context of industrial applications. The proposed research will aim to identify efficient size specification approaches applicable to meshes of mixed element types. Themes related to a posteriori mesh adaptation include a posteriori error estimation for incompressible turbulent Navier-Stokes finite volume solutions, the combination of several variables to steer adaptation and convergence of mesh adaptation algorithms.