Impact of rotating cylinders configurations on Cu-water nanofluid heat transfer in a vented cavity: a COMSOL multiphysics base study

This study investigates forced convection heat transfer and fluid flow in a square vented cavity filled with Cu-water nanofluid, containing three rotating cylinders. This configuration is relevant for thermal performance optimization in compact systems such as electronic cooling, battery packs, and microfluidic heat exchangers. Unlike prior studies that considered only one or two rotating cylinders, this work introduces a more complex model with three cylinders under four distinct rotation configurations, allowing comparative evaluation of individual and collective effects on flow and heat transfer. The Galerkin finite element method (FEM) was applied using COMSOL Multiphysics 6.3 to solve the dimensionless governing equations for momentum and energy transport in the nanofluid system. Simulations are conducted for specific ranges of key physical parameters, including the Reynolds number [Formula: see text], rotational Reynolds number [Formula: see text], nanofluid volume fraction [Formula: see text], and also inlet/outlet port positions across four distinct cases for cylinders rotations. The Reynolds number is fixed at [Formula: see text], while [Formula: see text] is varied (0, 50, 100), along with nanoparticle volume fractions [Formula: see text].The Prandtl number is held constant at Pr = 4.1588, reflecting the thermophysical properties of the Cu-water nanofluid. At Reynolds number [Formula: see text]and nanoparticle volume fraction [Formula: see text], the maximum Nusselt number of 16.405 was achieved when all cylinders rotate at [Formula: see text]. Scenarios with a non-rotating central cylinder (C2) showed significant reductions in heat transfer due to suppressed flow circulation. Cylinder rotation pattern and nanoparticle concentration can be strategically adjusted to enhance localized convective heat transfer. The model provides practical insights for the design of advanced cooling systems where rotational enhancement is feasible.