Computational Modeling of Heat Transfer Characteristics in Copper-water Nanofluids with Nonlinear Thermal Effects

Abstract

This study numerically investigates the three-dimensional mixed-convection flow and heat-transfer behaviour of a copper-water nanofluid over a nonlinear stretching surface in the presence of a magnetic field, thermal radiation, Joule heating, viscous dissipation, and non-uniform heat-source/sink effects. The governing boundary-layer equations are formulated using effective nanofluid properties and transformed into a coupled system of nonlinear ordinary differential equations through similarity transformations. The resulting equations are solved using a shooting procedure combined with the Runge–Kutta–Fehlberg integration method under the prescribed boundary conditions. The effects of the mixed-convection, magnetic, thermal-radiation, heat-generation, velocity-slip, thermal-slip, Eckert-number, and nanoparticle-volume-fraction parameters are evaluated through velocity, temperature, skin-friction, and local Nusselt-number results. Increasing the mixed-convection parameter enhances the primary and secondary velocity profiles and raises the temperature distribution, whereas the magnetic parameter suppresses both velocity components through the Lorentz force. Higher thermal-radiation and heat-generation parameters increase the temperature and thermal-boundary-layer thickness. The nanoparticle volume fraction increases the skin-friction coefficients, while velocity slip reduces wall shear and thermal slip lowers the local Nusselt number. Across the reported parameter values, the local Nusselt number increases from 9.925833 to 59.561509, corresponding to approximately 500.1%. The findings characterise the coupled thermal and electromagnetic controls relevant to copper-water nanofluid systems used in heat-transfer and water-engineering applications.