Influence of shallow gaps on compressible boundary-layer transition

The aviation industry is constantly demanding further increase in the fuel efficiency of aircraft, e.g. by a reduction in drag. One of the most promising technologies is the use of laminar wings, i.e. wings in which the laminar properties of the incoming flow extend along the wing surface much longer that on current wing designs [2]. Unfortunately, the different components of the wing introduce unavoidable surface imperfections, such as steps, gaps, humps, etc. These irregularities might lead to an upstream displacement of the expected laminar-turbulent transition location compared with a clean configuration (i.e. without surface irregularities).