Computational analysis of backward facing step flow using OpenFOAM®

Abstract

The most widely investigated model for the study of flow separation is the Backward Facing Step (BFS). The separation phenomenon can be found in several aerodynamic and heat transfer systems. The sudden decrement in the pressure gradient due to expansion of the flow leads to the separation of the shear layer at the step edge resulting in the formation of a separation bubble. The extent of the recirculation region is devised from the measurement of the re-attachment length. These measures are dependent on the flow and geometric properties. The chaotic interactions of the vortices shredded from the step edge and the upper wall surface open a wide domain to explore and study its characteristics. Several researchers in the past have theoretically, experimentally, and computationally obtained outcomes to study these kinds of flows. The present study was performed to investigate the complex interactions between the vortices formed at the step edge, the upper wall, and the secondary vortices forming in the secondary re-circulation region. The simulation was performed using an open-source CFD software package; OpenFOAM® using a transient incompressible solver which incorporates the PISO (Pressure Implicit with Splitting of operators) algorithm to solve the pressure-velocity linked equations. The visualisation outcomes at the uniform time interval of 0.001 seconds were presented along with several energy modes identified using the mathematical technique of POD (Proper Orthogonal Decomposition) were also presented in this script.