Vol.26, No.1, 2026, pp. 85–92
https://doi.org/10.69644/ivk-2026-01-0085

THERMOSOLUTAL CONVECTION IN A WALTER’S (MODEL B') NANOFLUID IN A POROUS MEDIUM: RIGID-RIGID AND RIGID-FREE BOUNDARY CONDITIONS

Ajit Kumar , Pushap Lata Sharma* , Praveen Lata

Department of Mathematics & Statistics, Himachal Pradesh University, Summer Hill, Shimla-171005, INDIA

A. Kumar https://orcid.org/0000-0002-5888-3761 ; P.L. Sharma https://orcid.org/0000-0001-5848-9214 ;

P. Lata https://orcid.org/0009-0002-9726-8814 , *email: pl_maths@yahoo.in

 

Abstract

This study investigates the stability of thermosolutal convection in Walter's (model B') nanofluid saturated in a porous medium under two different boundary conditions: rigid-rigid and rigid-free. Linear stability analysis is conducted using perturbation theory and normal mode analysis to evaluate the system's stability. The effects of Brownian motion and thermophoresis are incorporated into the nanofluid model. The nanoparticle Rayleigh number, thermosolutal Lewis number and solutal Rayleigh number have a destabilising effect, enhancing the onset of convection. In contrast, parameters such as porosity, thermo-nanofluid Lewis number, modified diffusivity ratio, Dufour parameter and Soret parameter have a stabilising effect, delaying the onset of convection. Effects of these parameters are presented graphically using MATLAB® software. This study improves the understanding of thermosolutal convection in nanofluid-saturated in a porous medium, with implications for optimising heat and mass transfer in applications like chemical reactors, oceanic convection, material synthesis, food processing and biological systems.

Keywords: • thermosolutal convection • nanofluid • Walter’s (model B') • Rayleigh number • porous media

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