Propulsion by an Oscillating Thin Airfoil at Low Reynolds Number

This paper describes an investigation of the mechanisms producing thrust for an airfoil performing a pitching or heaving motion in a low Reynolds-number flow (Re = 1000, based on chord length) by analysis of numerically obtained flow fields and forces on the airfoil. For heaving motion the dependence on reduced frequency and non-dimensional heaving amplitude are examined. For pitching motion the reduced frequency and the center of rotation are varied. The vortex generated by the leading edge is found to be determinant for thrust by heaving motion. Pitching propulsion is shown to be an effect of coupled acceleration and inclination of the airfoil.