Stratified tri-hybrid nanofluid flow over co-rotating cone–disk surfaces with endothermic/exothermic reactions

Purpose Stratified fluid flow over rotating surfaces is central to applications such as chemical reactors, rotary machinery and thermal storage units. However, how stratification interacts with chemically reactive nanofluids at independently rotating cone and disk surfaces remains unexplored. This paper aims to investigate tri-hybrid nanofluid (THNF) flow and heat transfer in a cone-disk system, incorporating endothermic and exothermic reaction effects in the energy equation. Design/methodology/approach The flow model of the cone-disk system with stratified fluid, rotation and endothermic and exothermic reactions is presented as a set of nonlinear governing equations and boundary conditions. These equations are reduced to a system of ODEs via suitable self-similar transformations and solved numerically using the bvp4c scheme in MATLAB. Results are presented in tables and graphs. Findings The study reveals that solutal stratification improves disk-surface heat transfer under exothermic reactions, while endothermic reactions enhance heat transfer at the cone surface. However, the stratification parameter generally suppresses heat transfer at both surfaces, independent of rotating surface, except under these specific reactive conditions. Compared to Newtonian THNF, disk-surface heat transfer improves by 38.56% under exothermic reaction with tri-hybrid nanoparticles (2% volume fraction each), whereas cone-surface heat transfer rate decreases by 18.17% for Casson THNF. Originality/value To the best of the authors’ knowledge, this is the first study to investigate a thermal and solutally stratified Casson fluid flow in a rotating cone–disk system under endothermic and exothermic reaction effects. A tri-hybrid ferro-nanofluid is used to quantify both the individual and synergistic effects of multiple nanoparticles on the thermal and concentration fields.