An ALE formulation of embedded boundary methods for tracking boundary layers in turbulent fluid-structure interaction problems
An ALE formulation of embedded boundary methods for tracking boundary layers in turbulent fluid-structure interaction problems
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DOI：
10.1016/j.jcp.2014.01.018
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发表时间：
2014-04-15
影响因子：
4.1
通讯作者：
Lakshminarayan, Vinod K.
中科院分区：
文献类型：
--
作者：
Farhat, Charbel;Lakshminarayan, Vinod K.
计算流体动力学（CFD）的嵌入边界方法（EBM）通常在欧拉环境中构造。它们对于以大的结构运动和变形为特征的复杂的流固耦合（FSI）问题特别有吸引力。它们对于拓扑变化的流动问题和开裂的流固耦合问题也是至关重要的。对于所有这些问题，替代的任意拉格朗日-欧拉（ALE）方法往往是不可行的，因为网格交叉的问题。然而，对于粘性流，CFD的欧拉EBM不跟踪动态刚性或柔性体周围的边界层。因此，这些方法的粘性流固耦合问题的应用程序需要一个高的网格分辨率在很大一部分的计算流体域，或自适应网格细化。不幸的是，第一种选择计算效率低，第二种选择劳动密集型。由于这些原因，本文提出了一种替代方法，用于在使用CFD的EBM模拟湍流FSI问题期间保持所有运动边界层的解决。在这种方法中，这是简单的和计算上合理的，底层的非贴体网格刚性平移和/或旋转，以便跟踪动态障碍物的运动的刚性分量。然后，远离嵌入面的流动计算采用ALE框架，壁面边界条件采用CFD的欧拉EBM方法处理。因此，本文提出的边界层跟踪问题的解决方案可以描述为一个ALE实现的CFD给定的EBM。用非贴体网格的大涡模拟方法模拟了翼型在垂荡运动中的湍流流动，说明了其基本特征。它的强大的潜力，具有挑战性的FSI问题的解决方案，在合理的计算成本也证明了与模拟湍流过去的一个家庭的高度灵活的扑翼。(C)2014年爱思唯尔公司All rights reserved.
Embedded Boundary Methods (EBMs) for Computational Fluid Dynamics (CFD) are usually constructed in the Eulerian setting. They are particularly attractive for complex Fluid-Structure Interaction (FSI) problems characterized by large structural motions and deformations. They are also critical for flow problems with topological changes and FSI problems with cracking. For all of these problems, the alternative Arbitrary Lagrangian-Eulerian (ALE) methods are often unfeasible because of the issue of mesh crossovers. However for viscous flows, Eulerian EBMs for CFD do not track the boundary layers around dynamic rigid or flexible bodies. Consequently, the application of these methods to viscous FSI problems requires either a high mesh resolution in a large part of the computational fluid domain, or adaptive mesh refinement. Unfortunately, the first option is computationally inefficient, and the second one is labor intensive. For these reasons, an alternative approach is proposed in this paper for maintaining all moving boundary layers resolved during the simulation of a turbulent FSI problem using an EBM for CFD. In this approach, which is simple and computationally reasonable, the underlying non-body-fitted mesh is rigidly translated and/or rotated in order to track the rigid component of the motion of the dynamic obstacle. Then, the flow computations away from the embedded surface are performed using the ALE framework, and the wall boundary conditions are treated by the chosen Eulerian EBM for CFD. Hence, the solution of the boundary layer tracking problem proposed in this paper can be described as an ALE implementation of a given EBM for CFD. Its basic features are illustrated with the Large Eddy Simulation using a non-body-fitted mesh of a turbulent flow past an airfoil in heaving motion. Its strong potential for the solution of challenging FSI problems at reasonable computational costs is also demonstrated with the simulation of turbulent flows past a family of highly flexible flapping wings. (C) 2014 Elsevier Inc. All rights reserved.