Turbulent Boundary Layer CFD

Abstract

In every aerodynamic design, skin friction drag on the boundary layer of the surface needs to be taken into account. The neglect of this could cause a significant error in drag and lead to a faulty design. The aerodynamics of skin friction drag can be assessed using computational fluid dynamics (CFD). CFD is a method that uses numerical algorithms to solve and analyze fluid flow, which can then be used to predict physical flow. The present study analyzed skin friction drag caused by small geometric changes on a surface using the commercial software ANSYS Fluent. This software offers a widely tested shear stress transport (SST) turbulence model. Fluent combines the SST model with other turbulence modeling innovations for maximum accuracy in wall shear, which corresponds directly to skin friction drag. Because of the number of elements needed for this analysis, this study pushed the limits of the software version and computational power available. This project provided a deeper understanding of turbulence modeling that allowed for the prediction of the local skin friction coefficient for different flows and surface geometries. Further analysis with more complicated surface geometries will provide engineers with a more thorough understanding of fluid surface interactions and its effects on skin friction drag. This information can then be used to optimize aerodynamic surfaces.