Optimizing entropy generation in MHD Maxwell dusty nanofluid flow via nanoparticle radius and inter-particle spacing on an inclined stretching sheet.

This study presents a numerical investigation of entropy generation in a magnetohydrodynamic (MHD) flow of a Maxwell dusty nanofluid over an inclined stretching sheet, with a focused analysis on the previously overlooked parameters of nanoparticle radius and inter-particle spacing. The model incorporates the effects of viscous dissipation and thermal buoyancy on the flow dynamics. The governing partial differential equations are transformed into a system of nonlinear ordinary differential equations via similarity transformations and solved computationally using MATLAB's bvp4c solver, with validation against published results confirming high accuracy. The findings quantitatively show that nanoscale particle geometry is a key factor influencing thermal performance and irreversibility. A reduction in the nanoparticle radius from 3.6 nm to 1.6 nm under standard conditions ([Formula: see text], [Formula: see text], [Formula: see text]) suppresses total entropy generation by approximately [Formula: see text]. Conversely, increasing the nanoparticle radius beyond 2.5 nm enhances both the fluid and dust phase velocities by nearly [Formula: see text], which is beneficial for flow applications, but concurrently reduces the effective thermal conductivity by almost [Formula: see text] due to a diminished surface-area-to-volume ratio. Furthermore, the analysis shows that increasing inter-particle spacing decreases entropy generation by reducing particle clustering. This study bridges a crucial research gap in the literature by quantifying the role of nanoparticle microstructure. It provides an operational framework for developing high-efficiency, low-irreversible thermal control systems in industries such as advanced manufacturing and energy production.