Numerical investigation of vortices effect on the pressure drop and flow loss in a channel with planar gradual expansion

The main object of current study is investigation of influence and role of symmetric and asymmetric vortices formation and number of them on the pressure drop and losses of flow in gradual expansions. For creating symmetric and asymmetric vortices, laminar flow of Newtonian fluid is simulated in a channel with a planar gradual expansion for the expansion ratio of 1:3. Discretization of the governing equations is performed with utilization finite volume method (FVM) in two-dimensional. Also, the velocity and pressure are coupled based on the PISO algorithm on a collocated mesh. To study effect of vortices, analyze and calculation of pressure and loss coefficients has been done for a wide range of expansion angles and in different Reynolds numbers . Therefore, to assess the validity of this study, results from the expansion angle of 90° are compared with past researches, which is in very good agreement with previous studies. Streamlines and pressure contours for the analysis and understanding of flow dynamics is depicted. To investigate the role of symmetry and non-symmetric of vortices and the effect of the number of vortices, graphs of pressure changes on the central line of the channel, pressure and loss coefficients have been traced and analyzed as a function of expansion angle and Reynolds number. The remarkable point in this study is that the pressure and loss coefficients in the expansion angle of 53 degrees are independent of the Reynolds number for fluid flow through the planar gradual expansion channel.