The strakes are small wings placed upstream a main wing, that are used to
modify the downstream vortical flow. A typical application is in agile aircraft
(e.g. fighters). The strakes are one of those examples where the interference can be
largely beneficial both from the aeodynamic point of view (lift) and control (effects
on rolling and bending moments, see below). Similar effects can be achieved
with a long leading edge extension (which makes a smooth wing-body combination).