Linear and Nonlinear Decomposition of Aerodynamic Force Acting on an Oscillating Plate

An exact Lamb vector-based theory for the computation and decomposition of the aerodynamic force in unsteady viscous flows is presented and analyzed. This decomposition allows for a correct and straightforward computation of the dynamic force derivatives even in strongly nonlinear flows. Theory has been applied to numerical solutions around a pitching and plunging plate at low (300) and high (10(6)) Reynolds numbers. A breakdown between thrust and drag contributions is also obtained, evidencing the flow regions where the thrust force is generated. The obtained decomposition is compared with the classical analytical linear inviscid theories. In addition, a new mixed inertial-non-inertial formula is proposed for the computation of the aerodynamic force, which is more accurate when dealing with high Reynolds numbers flows.