Two-dimensional simulation of dynamic surface roughness for aerodynamic flow control

This study addresses the issue of controlling flow separation through the use of dynamic surface roughness. The work focuses on two areas: 1) development of simulation tools for detailed analysis of moving flow boundaries and 2) investigation of the effects of dynamic roughness on aerodynamic flow separation. The process of generating a quality grid for a surface that contains complex roughness can be a labor-intensive project. The addition of dynamic surface roughness, or roughness that grows (or shrinks) in time, can further complicate this process. The current study proposes a method that not only accounts for the perturbations to the surface but also allows for the surface to move dynamically, which produces a robust gridding method that is well suited for this application. The method is applied to dynamic surface roughness in the leading-edge region of an airfoil but could also he used for analysis of internal surface roughness. The dynamic surface roughness examined in this study demonstrated a major effect on the flow field, with the resulting flow being significantly different than the flow found with similar static surface roughness. The dynamic roughness was able to delay or eliminate the unsteady flow separation for the conditions tested at both constant angle of attack and dynamic stall regimes and shows strong potential as an aerodynamic-flow-control mechanism.