This study examines bioconvective flow and entropy generation (EG) in metal-based nanofluids containing gyrotactic microorganisms under the influence of a magnetic field and thermal radiation. The flow is modelled between two parallel plates undergoing squeezing, and its thermodynamic irreversibility is assessed using EG and the Bejan number. Water is considered the base fluid, while copper, silver, and gold nanoparticles are introduced to modify its thermal and electrical properties. The governing system consists of coupled nonlinear ordinary differential equations describing momentum, microrotation, temperature, species concentration, microorganism density, and EG. These equations are solved numerically using a fourth-order Runge–Kutta method together with a shooting technique. Entropy production associated with thermal gradients, viscous dissipation, and magnetic effects is also quantified. The results indicate that increasing the Hartmann number decreases the momentum boundary-layer thickness due to magnetic damping. Variations in nanoparticle electrical conductivity influence the velocity distribution across the channel. Higher values of spinning and squeezing parameters lead to a reduction in fluid velocity. At the same time, the gold–water nanofluid exhibits a thicker thermal boundary layer compared to silver– and copper–water nanofluids. An improvement in the Peclet number enhances the transport of motile microorganisms toward the squeezing direction. The findings are relevant to confined flow applications such as micro-cooling systems, magnetically regulated thermal channels, and micro-scale bioreactors, where controlled transport and energy efficiency are of interest.
Srinivasu et al. (Wed,) studied this question.