A novel approach to calculating induced drag from computational fluid dynamics

Abstract

Early aerodynamic mathematical methods rely on potential flow concepts that formally isolate aerodynamic drag into a profile and an induced drag component. The more recent evolution of Navier–Stokes-based Computational Fluid Dynamics (CFD) methods typically directly computes aerodynamic forces. It does so using surface integration of pressure and viscous forces, which does not readily enable conventional separation of profile and induced drag. Isolating induced drag from aerodynamic drag is not well developed using CFD, leading to the present effort that derives a mathematical framework to extract induced drag from CFD model results. The present approach builds on mass, momentum, and energy equation control volume analysis performed within the CFD results. We find that the energy equation provides the necessary means for the closure of quantifying induced drag within the context of minor assumptions. In addition, the results indicate an interesting character in the development of energy losses in the context of induced drag associated with flow reorganization into a tip vortex. The results from the approach indicate accuracy in the method as displayed with good correlation to predictions from analytical and potential flow methods for a variety of wing planforms. Results indicate a novel and efficient method to extract induced drag from CFD models.