Influence of internal heat source on penetrative convection in a dual-component hybrid nanofluid layer

This study investigates the influence of internal heat sources on penetrative convection in a horizontal layer of a common composite nanofluid subjected to bottom heating and salting. The nanofluid layer, composed of two different types of nanoparticles suspended in a base fluid, is analysed to understand the onset of convection under varying physical and thermal conditions. The use of a composite formulation aims to capture the enhanced thermophysical properties arising from the synergistic effects of mixed nanoparticles, offering a broader perspective on stability behaviour compared to conventional nanofluids. The system exhibits complex thermosolutal convection, influenced by double-diffusive effects, internal heat generation, and the distribution of nanoparticles. A linear stability analysis is performed using the single-term Galerkin method, which is applied to the governing equations derived under the Boussinesq approximation. The approach enables the determination of the critical Rayleigh number, providing insights into the stability characteristics of the fluid layer. Various configurations, such as top-heavy, bottom-heavy, and uniform nanoparticle distributions, are explored to assess their impact on convective stability and heat transfer efficiency. The results indicate that top-heavy configurations enhance system stability by raising the critical Rayleigh number, while bottom-heavy arrangements promote instability. An increase in the internal heat source parameter stabilizes the system by requiring a higher temperature gradient to initiate convection. Moreover, a reduction in the modified diffusivity ratio leads to improved thermal performance by lowering the Rayleigh number. The analysis also identifies optimal wavenumber ranges where heat transfer is maximized. These findings contribute to a deeper understanding of the interplay between internal heating, solutal effects, and nanoparticle behavior in ordinary nanofluids. The outcomes have practical implications for the design and optimization of thermal management systems in areas such as energy engineering, electronic cooling, and biomedical device development.