Enhanced heat transfer and flow control in Oldroyd-B hybrid nanofluids: A study on electro-osmosis effects and thermal characteristics

• Examines electro-osmosis in stratified Oldroyd-B hybrid nanofluid on an inclined sheet. • Analyses viscous and Joule heating effects of silver and alumina nanoparticles. • Uses Cattaneo-Christov model with variable heat source and thermal radiation. • Electro-osmosis boosts velocity, but effect reduces as Forchheimer number grows. Electro-osmosis in hybrid nanofluids shows enormous potential for enhancing thermal conductivity and controlling fluid movement, which is important for improving heat transfer systems in industries and medical applications. This work examines the steady electroosmotic flow of thermally stratified Oldroyd-B hybrid nanofluid comprising silver (Ag) and alumina (Al₂O₃) nanoparticles over an inclined, stretchy surface. We analyse the impacts of a variable heat source, thermal radiation, and stratification using the Cattaneo–Christov method. To analyse the physical behaviour, the governing nonlinear partial differential equations are reduced to ordinary differential equations via similarity transformations and solved numerically using the fourth-order Runge–Kutta method. Electro-osmosis increases velocity by 16%, while Forchheimer decreases it by 23%. Hybrid nanoparticles enhance heat transport by 18%. Viscous dissipation and radiation augment thermal layer thickness by 20%, enhancing energy systems and biomedical applications. Additionally, surface drag increases with radiation but decreases with higher viscoelasticity (β₂). The quantitative findings reveal that the boundary layer velocity increases from about 0.39 to 0.48 as m e escalates from 0.2 to 1, signifying electro-osmotic enhancement. Nonetheless, it decreases from around 0.48 to 0.40 as F s (0–0.9) increases, indicating decreased flow momentum attributable to heightened porous resistance resulting from the Forchheimer effect. The thermal profile θ(η) increases from approximately 0.34 to 0.54 at η = 1 with an increase in the heat source A ∗ (0.5–2.5), while it decreases from approximately 0.51 to 0.34 as the relaxation time β increases (0–3). Stratification δ decreases temperature from approximately 0.50 to 0.37, indicating contrasting thermal behaviors. These findings offer helpful advice regarding for the design and optimization of electrokinetic thermal systems in cooling technologies, energy devices, and biomedical applications.