Definition of an Invariant Lamb-Vector-Based Aerodynamic Force Breakdown Using Far-Field Flow Symmetries

Abstract

Some recent developments in the Lamb-vector-based aerodynamic force breakdown used the concept of vortex force to define the lift and to decompose the drag into lift-induced drag and profile drag. However, the Lamb vector formulation involves moment transformations, and the associated force breakdown may depend on the reference point adopted for their computation. Yet, the force acting on an airplane cannot be dependent on this point. Thus, a systematic method based on the far-field flow symmetries is here proposed to eliminate this dependence. Those symmetries also allow for a better understanding of the progressive invariance of the drag decomposition with respect to the size of the integration domain. Finally, a reference-point-invariant formulation is defined and tested for a 2-D transonic flow around an OAT15A airfoil and a 3-D flow around the NASA Common Research Model under cruise flight conditions.