Numerical Differential Quadrature Examination of Steady Mixed Convection Nanofluid Flows Over an Isothermal Thin Needle Conveying Metallic and Metallic Oxide Nanomaterials: A Comparative Investigation

The significance of the local skin friction as well as the heat transfer rate on the motion of water \( \left( {{\text{H}}_{2} {\text{O}}} \right) \) and ethylene glycol \( \left( {{\text{C}}_{2} {\text{H}}_{6} {\text{O}}_{2} } \right) \) conveying metallic and metallic oxide nanoparticles (e.g., Al, Cu, Zn, Al₂0₃, CuO and ZnO) along a vertical thin needle is needed to improve the performance of chemical reactors, heat exchangers, pharmaceutical equipment and hybrid-powered engines. This led to the investigation of mixed convection flow and heat transfer of some nanofluids, in which the thermal conductivity and viscosity vary nonlinearly with the volume fraction. For simplifying the present investigation, appropriate variables were introduced successfully in the mathematical formulation to convert the governing nonlinear partial differential equations to coupled ordinary differential equations (ODEs). Moreover, the resulting ODEs were solved numerically via a robust differential quadrature algorithm. Furthermore, a comparative study with the existing literature is found to be in an excellent agreement. The enhancement of heat transfer in nanofluids is ascertained by increasing the convection ratio. Generally, the maximum improvement in the local skin friction was perceived for the flows of zinc–water-based nanofluids (\( {\text{Zn}} \)–\( {\text{H}}_{2} {\text{O}} \)) with the upsurge in the volume fraction of the nanoparticles \( {\text{Zn}} \). On the contrary, the highest enhancement in the heat transfer rate was revealed for the flows of copper–ethylene glycol-based nanofluids (\( {\text{Cu}} \)–\( {\text{C}}_{2} {\text{H}}_{6} {\text{O}}_{2} \)) with the increase in the weight percent of the \( {\text{Cu}} \) nanomaterial loading.