The fourth symposium on the doctoral research of the von Karman Institute for Fluid Dynamics took place during the period March 4 to 6, 2013. The doctoral students have presented the progress of their research work carried out in the three departments: Aeronautics and Aerospace, Environmental and Applied Fluid Dynamics, Turbomachinery and Propulsion. The articles written at this occasion are available for free download in the VKI STORE.