Analysis of Nanofluid Flow Over a Heated Circular Cylinder using the Volume of Fluid (VOF) Approach

Abstract

This study employs a two‐phase Volume of Fluid (VOF) model to investigate the flow and heat transfer characteristics of Al₂O₃-water nanofluid over a heated circular cylinder at a Reynolds number of 100. Nanoparticle volume fractions (Φ) ranging from 1% to 10% were analyzed. A comprehensive grid-independence study and code validation were conducted to ensure the accuracy of the results. Increasing (Φ) from 0% to 10% led to significant changes in flow parameters: the mean drag coefficient increased by 27.8% (from 1.33 to 1.7), the fluctuating lift coefficient rose by 56.5% (from 0.23 to 0.36), and the Strouhal number increased by 6.7% (from 0.164 to 0.175). Heat transfer enhancement was observed with increasing nanoparticle concentration, as evidenced by the local Nusselt number at the front stagnation point (θ = 0°) rising by approximately 40% over the same (Φ) range. The study revealed significant changes in pressure distribution around the cylinder, with higher (Φ) values smoothing the pressure gradient and altering the separation point. Time-averaged temperature contours demonstrated more uniform thermal distributions and reduced wake sizes at higher (Φ) values, indicating improved thermal diffusion and heat transfer efficiency. The (VOF) model successfully captured complex two-phase flow dynamics, revealing asymmetric nanoparticle distributions in the wake region at higher concentrations. These findings have important applications in thermal management systems, including electronic and energy systems, potentially leading to more efficient cooling systems and heat exchangers.