Large Eddy Simulations of 2D and Open-tip Airfoils Using Voxel Meshes

Abstract

This paper presents Large Eddy simulations of flow and acoustic computations around 2D and 3D airfoils using a novel type of mesh called voxel mesh. Voxel mesh refers to the mesh that has different number of nodes in the neighbouring cell layers. Voxel mesh has many advantages such as creating cells with minimum skewness, automatic mesh generation and uniformity in cell shapes and sizes. The voxel meshes aren’t yet validated in boundary layer computations. In this paper we validate the use of voxel meshes in boundary layer computations in 2D and 3D airfoils. Six cases were tried out in the research three 2D meshes and three 3D cases were tried out. Each case was simulated at Reynolds number 2.83×105 and attack angle of 90. Flow field computation was done by FrontFlowBlue-7.2 software the acoustic computation was done by using FrontFlowBlue-Acoustic2.2 software. The results obtained from the simulations were compared with the experimental values. The use of voxel meshes to resolve the boundary layer in turbulent fluid flows could be validated using 2D airfoils. Therefore voxel meshes were used in 3D airfoil flow computations. After successful flow computations the source fluctuations in the flow was used for the acoustic computations. The sound pressure levels computed from the acoustic computations were compared with the experimental values. Some oscillation in the pressure could be observed due to the step like structure at the surface of voxel mesh but these variations were less apparent in meshes that had smaller cells.