Numerical Study of Laminar Flow Separation in Step Geometry Using Corners Formulation in Lattice Boltzmann Method

Abstract

In this study, the velocity and temperature distributions of incompressible laminar flow of a step downstream have been investigated using the lattice Boltzmann method. The inlet and outlet flows at internal and external corners of this step have been simulated using the single relaxation time model in various Reynolds number and expansions ratios, two dimensionally. According to Zou and He, constant temperature boundary conditions and open-boundary condition have been utilized at inlet and outlet, respectively. The model results have been validated by experimental data. It was obtained that there are agreements between them. It was resulted that the length of recirculation zone is a function of Reynolds number of inlet flow. Increasing the Prandtl number decays the rate of fluid temperature decrement. Furthermore, in constant Reynolds and Prandtl numbers, decreasing the expansion ratio decreases the Nusselt number of flow. Generally, the ability of lattice Boltzmann method in simulating complex fluid and thermal flows has been shown.