Mixed Convection Nanofluid Transport Over an Exponentially Stretching/Shrinking Surface With Convective Boundary Conditions: Stability and Sensitivity Analyses Under Thermo‐Diffusion and Dissipation

Mixed convection nanofluid flowing through stretching/shrinking permeable sheet has significant applications in numerous thermal devices such as heat exchangers, microfluidics, cooling of electronic devices, and materials processing. Nevertheless, the combined role of convective boundary conditions, thermo‐diffusion, viscous dissipation, and flow stability in these configurations is still not well understood. In this work, the mixed convection flow with heat and mass transfer of water‐based AA7075 nanofluid over an exponentially stretching/shrinking permeable surface is investigated. The buoyancy, external forces, and Soret effects are taken into consideration to incorporate the coupling between momentum, temperature, and concentration fields along with convective boundary conditions. The boundary layer equations are reduced to similarity equations and solved numerically by the MATLAB solver bvp4c. Nonunique solutions are found in specific ranges of suction/injection, stretching/shrinking, and mixed convection parameters. Linear temporal stability analysis is carried out by using an eigenvalue method to determine the physically feasible solution. In addition, response surface methodology is used to investigate the interaction of parameters and optimize the heat and mass transfer. The findings reveal that the nanoparticle volume fraction, viscous dissipation, buoyancy forces, and thermo‐diffusion have significant effects on the flow behavior rates of heat and mass transfer. The present numerical, stability, and optimization framework provides useful insight for the design and operation of advanced nanofluid‐based thermal systems.