Numerical investigation of the effect of circular obstacles on flow and heat transfer in sinusoidal wavy channels

This study numerically investigates the effects of wave amplitude and circular obstacles on flow and heat transfer in sinusoidal wavy channels. Computational Fluid Dynamics (CFD) analyses were conducted using ANSYS Fluent with the finite volume method. Convective terms were discretized using a second-order upwind scheme and solved via the SIMPLE algorithm, employing the standard k-ε turbulence model. Wave amplitude (s), diameter of circular obstacles (d), and Reynolds number (Re) were varied while other parameters remained constant. Initially, analyses were performed for three different wave amplitudes (s = 20 mm, 30 mm, 40 mm) in channels without obstacles (d = 0). Subsequently, circular obstacles of varying diameters (d = 4 mm, 6 mm, 8 mm) were introduced at a fixed wave amplitude (s = 40 mm). Under turbulent flow conditions (3000 ≤ Re ≤ 8000), parameters including Nusselt number (Nu), heat transfer enhancement ratio (ER), pressure drop (ΔP), friction factor (f), relative friction factor (frel), and performance factor (PF) were evaluated. Results indicate that increasing wave amplitude and obstacle diameter enhances heat transfer, with a maximum improvement of 1.82 times compared to a smooth channel at s = 40 mm and d = 8 mm. However, this enhancement is accompanied by increased pressure losses. The highest performance factors were observed as 1.10 for d = 0 at Re = 4000, and 1.08 for d = 4 mm at Re = 8000. This study contributes to the design optimization of sinusoidal wavy channels, aiming to enhance flow and heat transfer performance.