Jyoti Ahuja
Department of Mathematics, Post Graduate Government College, Sector-11, Chandigarh, India.

Jyoti Sharma
University Institute of Engineering and Technology, Panjab University, Chandigarh, India.

DOI https://doi.org/10.33889/PMSL.2026.5.1.004

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Abstract

The present study considers the hybrid nanofluid convection problem under the local thermal non-equilibrium (LTNE) model. A horizontal pressure gradient is applied, which influences the initial profile of the velocity of the fluid layer. Linear stability analysis is applied to find the expression of thermal Rayleigh number and found to be a function of many non-dimensional numbers introduced due to LTNE and the hybrid character of the fluid. Further, the outcome is subsequently verified and contrasted with a less intricate convection system, leading to noteworthy observations. For a thorough investigation of the problem, metallic (copper, silver) and non-metallic (alumina, titanium dioxide) nanoparticles in base fluids (water and ethylene glycol) are used for numerical computations of the problem. The effect of nanoparticles destabilizes the system in LTE cases however additional impact of LTNE tends to postpone the onset of convection significantly. The hybrid character of the system makes it less stable than mono nanofluids in the LTE case. However, this does not apply to the LTNE model, where the onset of instability depends on the various physical characteristics of the system. To understand the deep insight into the convection process, various values of parameters are calculated and presented in the tables along with stability curves for hybrid and mono nanofluids which are analysed together. The analysis reveals that increasing the base-fluid conductivity and viscosity enhances the sensitivity of the layer, whereas higher density and specific heat of the base fluid suppress convection. An increase in thermal conductivity and nanoparticle volume fraction promotes system stability, while higher particle density and specific heat act to destabilize the layer. Water acts as a more stable base fluid than ethylene glycol due to its lower viscosity, highlighting viscosity as a dominant stabilizing property. Among the nanoparticles, alumina is more stabilizing than titanium dioxide due to its higher conductivity and lower density. Copper enhances the stability of water more effectively than alumina, though the order reverses for ethylene glycol, where particle density through the concentration Rayleigh number, becomes dominant. Silver nanoparticles make the layer more sensitive than copper particles because of their higher density and thermal diffusivity ratio.

Keywords- Local thermal non-equilibrium model, Hybrid nanofluids, Linear stability analysis, Horizontal pressure gradient, Metallic and non-metallic nanoparticles.

Citation

Ahuja, J., & Sharma, J. (2026). Linear Instability in Hybrid Nanofluids Under Horizontal Pressure Gradient and Local Thermal Non-Equilibrium Effects. Prabha Materials Science Letters, (1), 51-73. https://doi.org/10.33889/PMSL.2026.5.1.004.