Numerical Investigation of Laminar-Turbulent Flow in a Suddenly Expanding Channel

The article presents the results of a numerical study of the flowstructure in a flat channel in the zone of its sudden expansion in the form of a ledge. A characteristic feature of the sudden expansion in this case is considered to be that they exhibit complex anisotropic turbulence due to the recirculation of flows. The calculations are based on the numerical solution of a system of non-stationary equations using a new two-fluid turbulence model. The model provided is based on a two-fluid approach to the turbulence problem. A feature of the two-fluid model is that it is capable of describing complex anisotropic turbulent flows. In this paper, the results are obtained for determining the locations of the reattachment of the primary vortex, the beginning and end of the secondary vortex, and the profiles of the longitudinal velocity in various sections are calculated. For the difference approximation of the initial equations, the control volume method was used, and the relationship between velocities and pressure was found using the SIMPLE procedure. In this case, the viscosity terms were approximated by the central difference, and for the convective terms, a scheme of the second order of accuracy upstream was used. To confirm the correctness of the numerical results, a comparison with experimental data is made, and numerical results of other known turbulence models are presented. It is shown that the two-fluid turbulence model gives results closer to experimental data than others.