The investigations presented focus on the features of calculating the characteristics of vortex formation and decay processes that cause aerodynamic buffet loads acting on elements of aircraft at incompressible subsonic flow. Analysis of stability and numerical dissipation of differencing schemes implemented in OpenFOAM package has been carried out. Based on the obtained results, modification of some differencing schemes has been done. An algorithm for combining RANS and LES approaches for modelling turbulent flows has been briefly presented. A series of calculations of three-dimensional flow around an aircraft considering airbrake has been carried out.