Numerical investigation of large-scale coherent structures in flow between two parallel fins

Numerical simulations of axial flow in a rectangular channel with two parallel fins were conducted using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations coupled with a Reynolds Stress Model (RSM). The primary objective of this study is to investigate the formation of quasi-periodic coherent structures and their significant role in fluid transport across the inter-fin region. Computational Fluid Dynamics (CFD) results were validated against experimental data available in the literature, specifically for Strouhal numbers and the spacings of coherent structures in the five studied test sections, with a ratio of fin height to inter-fin spacing ranging from 2.5 to 7.5. The Reynolds number, based on the hydraulic diameter of the channel and the bulk velocity, was held constant at 40 × 10⁴. Velocity profiles and contours were analysed to capture and describe the presence of coherent structures within this family of finned rectangular channels.