The Embraer Legacy executive jet.

A winglet is a wing-like surface attached to the tip of the wing that is used to improve fuel efficiency and climbing capability. It accomplishes this by acting like a small sail with a lift component that generates a traction force, draining energy from the tip vortices. Consequently, it reduces the vortex strength, lowering induced drag.

Flow over the winglets must be optimized with the flow over the main wing so that the drag from the winglet doesn't become greater than the reduction in induced drag. Winglets also increase the bending moment at the wing root -- possibly requiring structural reinforcement. It is here that CFD can help by offering rapid turnaround times for parametric configuration studies. For example, it was through FLUENT simulations that the transition between the wing and winglet was optimized to achieve the best performance.

"We evaluated seven designs in only one month, ending up with a shape that was even more successful than we had hoped for," says Bento Silva de Mattos, senior engineer at Embraer.