Junction flows occur when a boundary layer encounters an obstacle (such as a wing) on its path. They can occurr either in laminar or turbulent flow conditions but only the turbulent case is considered here. This type of flow is usually a 3D, anistoropic, unsteady, turbulent flow. These characteristics are the result of two main phenomena. The most important one is called ”horseshoe vortex”, it is due to separation of the flow ahead of the obstacle caused by the adverse pressure gradient generated by the obstacle. The second one can be referred as ”secondary corner vortex” and it is triggered by gradients of Reynolds stresses and thus has no counterpart in laminar flow. These types of secondary flow are responsible for an increase in aerodynamic drag due to the interaction of the approaching boundary layer and the boundary layer developing on the obstacle.