Effect of Reynolds Number on Flow Control using Traveling Wave Morphing*

This study numerically investigates the effect of Reynolds number (Re) on the flow separation and aerodynamic performance (lift coefficient, C_L, and drag coefficient, C_D) of an airfoil under active flow control using low amplitude surface morphing in the form of backward (opposite to the airfoil's forward motion) traveling waves applied on the upper surface of the airfoil. A NACA0018 airfoil at a post-stall angle of attack (AOA = 20⁰) is simulated using the large eddy simulations (LES) curvilinear immersed boundary (CURVIB) method at distinct Reynolds number (Re = 5,000 to 500,000). While our previous investigations demonstrated the efficacy of backward traveling waves at pre-stall (AOA = 10⁰), stall (AOA = 15⁰), and post-stall angles of attack (AOA = 20⁰) at Re = 50,000, the efficacy of these waves at different Reynolds numbers has not been explored. The simulations of the baseline airfoil at AOA = 20⁰ and the Reynolds number range of Re = 5,000-500,000 are performed first. Afterward, the effect of traveling wave actuation with a low nondimensional amplitude of a* = 0.001 - 0.002 (a* = a/L; a: amplitude, L: chord length of the airfoil) and a reduced frequency range of f* = 8.0 (f* = fL/U; f: frequency, U: freestream velocity) will be investigated at the post-stall angle of attack (AOA = 20⁰) for the distinct Reynolds number (Re = 5,000 to 500,000). This work is supported by National Science Foundation (NSF) grant CBET 1905355, and the computational resources are provided by High Performance Research Computing (HPRC) group at Texas A&M University.