Inverse shape design method based on pressure and shear stress for separated flow via Elastic Surface Algorithm

Elastic Surface Algorithm (ESA), which was proposed for the inverse design in external flows, substitutes the airfoil wall by an elastic curved beam that deforms due to a difference between the target and current pressure distributions. The original ESA, such as all inverse design methods, which use only pressure as the target parameter, cannot converge in separated flows because of an almost constant pressure inside the separated region. This study developed the ESA for the inverse design in external separated flows by considering a linear combination of normalized pressure and shear stress distribution as the target flow parameter. Removing the geometrical filtrations, the automatic determination of the beam elasticity modulus, and the definition of dynamic spines instead of the vertical spines were the other essential modifications to upgrade the ESA for separated flows. The method was verified for blunt-leading-edged airfoils in subsonic turbulent flow under different angles of attack, and different initially-guessed geometries. The method reduced the separation by modifying the wall shear stress along the separation region.