Mixed convection and entropy generation analysis of carbon nanotube-water nanofluid in a square cavity with cylinders and flow deflectors

This study explores the mixed convection of carbon nanotube (CNT)-water nanofluid within a square cavity containing heated cylinders under the influence of a magnetic field, focusing on three geometric configurations: a single heated cylinder, two heated cylinders, and two heated cylinders with a flow deflector. The impact of various parameters, including Reynolds number (Re), Richardson number (Ri), Hartmann number (Ha), wavy wall peaks (n), nanoparticle volume fraction (ϕ), Hartmann angle (γ), rotational speed (ω), and inclination angle (α), on thermal and fluid dynamic behaviors is analyzed. MWCNT nanofluids exhibit up to a 19.1% increase in Nuave compared to SWCNT nanofluids, confirming their superior heat transfer performance. Adding a second heated cylinder increases Nuave by approximately 71.7% compared to a single-cylinder configuration, while the inclusion of a flow deflector modifies vortex structures, further enhancing convective transport. Increasing wavy wall peaks (n) enhances heat transfer by intensifying vortex formation and disrupting thermal boundary layers, leading to a more uniform temperature distribution. SWCNT nanofluids exhibit Bejan numbers up to 58.7% higher than MWCNT nanofluids, indicating greater thermal irreversibility. These findings provide valuable insights for optimizing thermal management systems in engineering applications, highlighting the importance of selecting appropriate nanofluids, geometric configurations, and magnetic field parameters to achieve optimal thermal performance and fluid stability.