The aerodynamic efficiency of a wing profile is the ratio between the lift and drag forces, and it is a measure of the wing performance. Obtaining higher aerodynamic efficiency means to allow the transportation of higher loads for the same fuel consumption.
In this video, we illustrate a set of high-fidelity numerical simulations aimed at evaluating different control strategies applied to a wing profile. Our results show that reducing skin friction, which is one of the contributions to drag, does not always guarantee higher performance. Indeed, one of the control strategies that we studied reduces skin friction, but it increases the pressure contribution to drag and reduce lift, eventually resulting in lower aerodynamic efficiency. Viceversa, a second control strategy improves aerodynamic efficiency even though it increases skin friction because it reduces pressure drag and increases lift.
These examples illustrate well how the complexity of turbulent flows makes it difficult to design effective control strategies. This task remains challenging nowadays, despite many decades of research on this topic.