Parameterization of a hexaedric mesh generation process for the application in the flow solution over a small scale wind turbine

Abstract

The present work has the main objective of defining parameters to the generation of a group of hexahedric meshes in order to simulate the flow over a small scale wind turbine (diameter of 3 m). In such way, the following stages were accomplished: Primarily the size of the control volume upstream and downstream of the turbine was defined. Afterwards, the mesh in areas of large velocity and pressure gradients was progressively refined. Finally, layers near the surface were added in order to improve the quality of the boundary layer modeling. The first two steps aimed to obtain the best relationship between the quality of the results and the computational effort in the mesh generation likewise numerical solution processes as well. In this investigation task, the control volume size was varied from larger to smaller ones, while the behavior of viscous and pressure moments acquired by the numerical solution were observed. For the analysis of the boundary layer and the mesh refinement close to the surface, the y+ value (dimensionless distance of the wall) was adopted as a reference parameter. For the turbulence model adopted, it was intended to achieve values smaller than 50 for y+, what guarantees a good boundary layer modeling according to the logarithmic law of the wall. The software used for this work was OpenFOAM, which is a free package for CFD solutions. To execute this work, applications and solvers were used for the mesh generation and the obtaining process of the flow ́s numerical solution, which applied the classic k-ε turbulence model, together with a second order discretization scheme. The present work is supported by the FUNCAP/CNPq/PPP.