Radiative heat transfer in MHD copper-based polymer nanofluid over a sphere using larger radius and inter particle spacing of nanoparticles

• The size and spacing of nanoparticles impact thermal resistance and heat transfer, essential for electronics cooling and heat exchangers. • 2. The study examines heat transport in a Carreau Cu-polymer nanofluid under MHD and radiative conditions, focusing on nanoparticle size and spacing effects. • 3. Nonlinear PDEs are converted to ODEs using similarity transformations and solved with the Bvp4c scheme. • 4. Larger nanoparticle size improves thermal conductivity and viscosity, while higher heat source values increase the temperature profile. • 5. Velocity decreases for smaller nanoparticle size and spacing but increases with larger sizes and spacing. The impact of nanoparticle size and interparticles spacing play a crucial role in fluid theology due to its significance on enhance heat transfer performance, which is crucial in many engineering and industrial processes particularly in thermal management systems. Due to this attention, the proposed study aims to explore the influence of nanoparticle radius and inter-particle spacing on thermal transport in a Copper (Cu) Polymer nanofluid over a sphere with radiative and magnetohydrodynamic (MHD) effects. Physical model incorporates Carreau fluid viscosity model. In addition, with incorporation of exponential heat generation and thermal radiation, the analysis reveals how tuning nanoparticle geometry significantly enhances heat transfer performance, which is critical for advanced thermal management systems. The governing nonlinear partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using similarity transformations and solved using the well-known bvp4c computational method. Results of proposed study indicate that larger nanoparticles and wider inter-particle spacing improve thermophysical and rheological behavior of fluid specifically thermal conductivity and fluid viscosity, which enhanced heat transport and intensified the temperature profile. Conversely, velocity profile decreases for smaller particle sizes and spacing but improves with increased nanoparticle dimensions.