COMPUTATIONAL ANALYSIS OF TURBULENT FLOW PHENOMENA IN BAFFLED RECTANGULAR CHANNELS: SINGLE VS. DOUBLE STEP CONFIGURATIONS

Abstract

The  present work shows computational analysis of fluid flow through a rectangular channel modified by single as well as double baffle steps utilizing the finite element method (FEM) within the COMSOL Multi-physics background. The study focuses on the complex relationship of boundary layer separation, vortex generation, and flow phenomena governed by the incompressible Navier-Stokes and continuity equations. To achieve a numerical solution, these second-order governing equations were converted into a first-order system by introducing vorticity as an additional unknown. Discretization was performed using the Galerkin finite element method coupled with a least squares residual approach to manage non-linearity and higher-order terms, while the Newton-Raphson method was utilized for final calculations. Steady-state simulations conducted across a Reynolds number (Re) range of 1 to 500 reveal that vortex formation is strongly dependent on fluid inertia. Results indicate that while no vortices appear at Re = 1, distinct primary and secondary vortices begin to form in the corners of the step baffles by Re = 50. As Re increases to 200, these vortices merge, and by Re = 500, the consolidated secondary vortex expands significantly to fill the entire channel domain. Comparative analysis between single- and double-baffle configurations shows that increasing the number of baffles facilitates more energetic and sustained vortex growth, with the double-step geometry reaching a maximum vortex length of approximately 0.20 compared to 0.06 in the single-step design at Re = 500. The numerical results demonstrate strong agreement with established literature, confirming the accuracy of the proposed computational approach for investigating flow efficiency and energy dissipation in baffled channels.