Validation of a Discrete Vortex Method for Low Reynolds Number Unsteady Flows

Abstract

An in-house discrete vortex method code based on steady and unsteady thin airfoil theory is used to rapidly resolve the flowfield and force coefficients for low Reynolds number unsteady aerodynamic applications. The Uhlman method is incorporated due to its ability to incorporate vortex motion, and surface effects in the volume and surface integrals make it ideal to calculate the pressure and the associated forces on the airfoil surface. The code is then used to study both low and high angle of attack impulsive motions, the AIAA Fluid Dynamics Technical Committee Low Reynolds Number Working Group 0–45 deg Pitch–Ramp–Hold Canonical cases, a similar 0–85 deg Pitch–Ramp–Hold to closer simulate perching, a 0–40–0 deg Pitch–Ramp–Hold–Return, and high reduced frequency pure plunge. In all cases, the flowfield and accompanying lift-and-drag results compared well with experimental and computational fluid dymanics results given the extent of the assumptions underlying the discrete vortex method.