Development of numerical and experimental methods for resolving of concentrated vortex structures

涡旋结构的求解是计算流体力学的主要问题之一。该项目的总体目标是开发能够探测更大范围的涡旋尺度的数值技术。在该项目中，采取了两种策略。一种是基于涡量约束(VC)方法的发展，另一种是基于基于网格的有限体积方法(FVM)和无网格涡街方法(CVM)相结合的新概念。这两种策略都旨在减少所有现有数值方法中存在的数值扩散量。作为涡量约束方法的一部分，在动量方程中引入了一项对数值扩散起作用的附加项。这一项将基于无网格涡旋法(CVM)进行计算。在混合FVM-CVM方法中，将旋涡分为大尺度结构和小尺度结构，大尺度结构用FVM建模，小尺度结构用CVM建模。这两种方法都将利用文献中关于机翼后叶尖涡流动的现有实验结果进行验证。涡旋结构识别算法的联合开发、在FVM OpenFoam中的实现和对相同测试用例的验证以及CVM结果在VC方法中的集成表明，这两个部分是紧密相连的，所开发的方法可以用于流体力学中广泛的基础和相关问题。

The resolving of vortex structures is one of the main problems in computational fluid dynamics. The overall objective of this project is to develop numerical technologies that can detect a wider range of vortex scales. In the project, two strategies are pursued. One is based on the development of the vorticity confinement (VC) method, while the other is based on a new concept that combines the grid-based finite volume method (FVM) with the grid-free vortex method (CVM). Both strategies aim to reduce the amount of numerical diffusion present in all existing numerical methods. As part of the vorticity confinement method, an additional term that can act against numerical diffusion is introduced into the momentum equation. This term will be calculated based on the grid-free vortex method (CVM). In the hybrid FVM-CVM method, the vortices are divided into large-scale and small-scale structures, where the former is then modelled with FVM and the latter with CVM. Both of these methods will be validated using in the literature available experimental results for tip vortex flow behind wings. The joint development of vortex structure identification algorithms, their implementation in FVM OpenFoam and their validation of the same test cases as well as the integration of CVM results in the VC-method show that these the both parts of the project are strongly interconnected, and the developed methods can be used for a wide range of fundamental and related problems in fluid mechanics.