The article is devoted to mathematical modeling of gas exchange processes. The features of modeling gas exchange processes based on gas dynamics equations are shown. The parameters of the gas flow are calculated by three conservation laws obtained by applying the general laws of physics to the elementary mass released in the flow, followed by a transition to the limit when the volume occupied by this mass tends to zero: momentum, mass, and energy. A mathematical model of the working process in the engine cylinder is created by the necessary conditions for calculating the entire gas exchange. Using a computer allows for a more accurate and complete description of all the main features. In the foreground is not the complexity and volume of calculations, but the accuracy of approximating the processes of fresh charge entering the engine cylinders, the air flow in the intake tract, the possibility of a comprehensive study of the effect on the filling process of each of the parameters of the intake tract design and gas distribution, and the features of the engine operation mode under study. Filling dynamic phenomena in the intake system has the main goal of optimizing engine design parameters.