Modeling the Flow of Multicomponent Reactive Gas on Unstructured Grids

Abstract

Introduction. The article deals with mathematical modeling of the subsonic flow of a multicomponent reactive mixture in a flowing chemical reactor. The numerical algorithm is based on the finite volume method; the calculation is performed on unstructured triangular grids using the Message Passing Interface parallel computing technology. Materials and Methods. To describe the flows under studying, the Navier–Stokes equations are used in the approximation for low Mach numbers. To solve these equations, the finite volume method on unstructured triangular grids is used. The study uses a splitting scheme for physical processes, namely, the chemical kinetics equations responsible for the transformations of substances are first solved, and then the equations describing the conservation laws of momentum and energy for each component of the gas mixture are solved. To find numerical flows through the edges of the grid elements, the Lax–Friedrichs–Rusanov scheme is used. To solve the equations of chemical kinetics, a compact algorithm proposed by the team led by N.N. Kalitkin is used. The METIS library is used to divide the grid into connected subdomains with an approximately equal number of cells. To organize parallel computing, Message Passing Interface technology is used. Results. The article presents a numerical algorithm for studying multicomponent gas flows on unstructured triangular grids taking into account viscosity, diffusion, thermal conductivity, and chemical reactions. As a result of the study, a numerical simulation of the flow of a subsonic multicomponent gas in a flowing chemical reactor was carried out using ethane pyrolysis as an example. Computational, known numerical solutions and experimental data of ethane pyrolysis in a flowing reactor are compared. Discussion and Conclusion. The numerical results on the conversion of the initial gas mixture are in good agreement with the known experimental data. The presented distribution patterns of the main components of the mixture and gas-dynamic parameters correspond to the flow pattern observed experimentally. Further work in this direction involves the modeling of subsonic gas flows on unstructured tetrahedral meshes using algorithms of higher accuracy for a more accurate study of ongoing processes.