Boundary layer flow and heat transfer characteristics of dusty hybrid nanofluid over multi-oriented surfaces with viscous dissipation effect

Enhancing heat transfer efficiency is crucial for the development of energy and thermal management technologies to develop high-performance systems such as advanced cooling devices, energy-efficient engines, and sustainable power generation units. Previous studies show that using a hybrid nanofluid can improve the heat transfer performance; however, the inclusion of dust particles provides a more realistic and relevant illustration for the flow and heat transfer models, as it constantly influences fluid dynamics. In addition, most studies focus on hybrid nanofluid models, with limited attention given to the combined dusty and hybrid nanofluid with the effects of viscous dissipation and slip conditions. Thus, this research aims to numerically analyse the flow and heat transfer characteristics of a dusty hybrid nanofluid over a multi-oriented stretching/shrinking surface, with the effects of viscous dissipation and slip conditions. The surfaces considered include horizontal, inclined, and vertical orientations, with alumina and copper nanoparticles used as hybrid components. Firstly, the governing equations are formulated according to the problem considered using Tiwari and Das model and are simplified to the boundary layer equations by implementing the boundary layer approximation. Then, the resulting equations are transformed into ordinary differential equations using a similarity transformation by introducing appropriate similarity variables. The transformed ordinary differential equations are solved numerically using the bvp4c function in MATLAB. The influence of pertinent parameters such as dust particle mass concentration, viscous dissipation, inclination angle, nanoparticle volume fraction, mixed convection, velocity slip, thermal slip, stretching/shrinking, and suction parameters is systematically analysed. The results indicate that dual solutions exist for certain ranges of suction and stretching/shrinking parameters. In addition, augmenting certain parameter values, such as dust particle mass concentration, mixed convection parameter, slip conditions, velocity slips, and copper nanoparticle volume fraction contributes to delaying the boundary layer separation. Furthermore, increasing the values of dust particle mass concentrations significantly elevates the skin friction coefficient and diminishes the heat transfer rate at the surface. The consideration of viscous dissipation, represented by the Eckert number, leads to a reduction in the heat transfer rate at the surface, which also depends on the flow configuration and orientation. Additionally, the extensive analysis indicates that horizontal surfaces exhibit the highest rate of heat transfer, followed by inclined and vertical surfaces. Besides that, copper nanoparticles show higher efficiency in comparison to alumina nanoparticles. Thus, the comparative analysis across the three surface orientations highlights the unique contributions of viscous dissipation, gravitational forces, and buoyancy on flow and heat transfer. The findings provide significant insights into engineering and industrial processes related to surface modification, heat exchangers, and hybrid nanofluid applications, where viscous dissipation, slip, and geometric configuration are the essential parameters in designing the devices.