The results of the theoretical solution of aerodynamic problems based on direct numerical simulation by integrating the Navier – Stokes equations without involving additional models and empirical constants are shown. Modern approaches to the theoretical study of high-speed flows are determined. The advantages, problems, development trends and scientific directions of research on various approaches are revealed. The advantages and disadvantages of the direct numerical simulation are analyzed. The velocity vectors of laminar and transient flows in a rectangular channel with a sudden expansion at the inlet are presented in different planes. The convergence of the method is studied when the computational domain is quantized in space. It is discovered that fast relaminarization is characteristic of transitional flows. A mathematical model for calculating bottom drag is presented. The numerical results are compared with the data of physical experiments and the results of other methods. It is shown that the results of simulation based on DNS are not inferior in accuracy to RANS and LES results. The results of a parametric study of a transonic flow around a profile are presented. The high-speed buffet onset is investigated. The distribution surfaces of the velocity pulsation energy generation are shown. The frequency of self-oscillations is determined on the basis of spectral analysis.