Modeling of a Three-Dimensional Incompressible Fluid Flow in a Turbulent Boundary Layer in a Diffuser

Within the framework of a three-dimensional boundary layer, the region of developed turbulent flow of an incompressible fluid under the action of a longitudinal unfavorable (positive) pressure gradient (hereinafter, referred to as UPG) in the diffuser is simulated. For a turbulent flow regime, the Reynolds-averaged Navier–Stokes equations in the boundary layer approximation are closed using a differential turbulence model based on the introduction of turbulent viscosity and the Kolmogorov–Prandtl hypotheses. Using the nonlinear least squares method (NLSM), correlation dependencies are found for the initial experimental data, which are further used in the numerical simulation. The calculated and experimental velocity profiles are compared in the region close to separation. Based on the numerical solutions of the turbulent boundary layer equations, the mechanisms of the interaction of the flows in the presence of transverse pressure gradients in an incompressible fluid are studied.