Radiative vegetable-oil/tetrahybrid nanofluid flow subject to bidirectional stretching and Robin’s conditions

Purpose The study aims to investigate the heat and mass transfer characteristics of a radiative vegetable oil-based tetrahybrid nanofluid under bidirectional stretching and Robin’s boundary conditions. It explores the effects of key parameters, including radiation, Brownian motion, Biot numbers and thermo-diffusion, on temperature and concentration distributions to enhance thermal performance in industrial and biomedical applications. Design/methodology/approach The study develops a radiative tetrahybrid nanofluid model by incorporating fundamental fluid mechanics laws and considering an unsteady, incompressible and laminar 3D boundary layer flow under a magnetic field while neglecting gravity, viscous dissipation and chemical reactions. The governing partial differential equations are made dimensionless using appropriate transformations and the optimal homotopy analysis method (OHAM) is employed to obtain analytical solutions for heat and mass transfer characteristics. Findings Radiation parameters and magnetic field effects enhance temperature while reducing species concentration, whereas higher Biot numbers improve heat and mass transfer. Bidirectional and unsteady stretching parameters reduce temperature and concentration, while Brownian motion and thermo-diffusion influence thermal-mass exchanges. The tetrahybrid nanofluid exhibits a higher local Nusselt and Sherwood number compared to mono-, bi-hybrid and tri-hybrid nanofluids, indicating superior heat and mass transfer performance. Research limitations/implications This study is limited by the assumption of an unsteady, laminar flow without chemical reactions, neglecting practical factors such as turbulence, nanoparticle agglomeration and real-world boundary complexities. Practical implications The study has significant practical implications in various engineering and industrial applications, particularly in thermal management, energy systems and biomedical engineering. The enhanced heat and mass transfer properties of the radiative vegetable oil-based tetrahybrid nanofluid can be applied in cooling systems, heat exchangers and advanced manufacturing processes where efficient thermal dissipation is crucial. The incorporation of Robin’s boundary conditions makes the model more adaptable to real-world scenarios, improving the design of nanofluid-based lubrication, solar energy harvesting and microfluidic devices. Social implications The use of vegetable oil-based tetrahybrid nanofluid enhances energy efficiency, reduces operational costs and extends equipment lifespan, making it a cost-effective solution for industrial and biomedical applications. Environmentally, it promotes sustainability by lowering carbon emissions, reducing waste and providing a biodegradable alternative to conventional coolants, supporting green technology advancements. Originality/value The originality of this study lies in the development of a novel tetrahybrid nanofluid model using vegetable oil as the base fluid, incorporating graphene oxide (GO), molybdenum disulfide (MoS2), titanium dioxide (TiO2) and alumina (Al2O3) nanoparticles and analyzing its radiative heat and mass transfer characteristics under bidirectional stretching with Robin’s boundary conditions.