Modeling the onset of thermosolutal convective instability in a non-Newtonian nanofluid-saturated porous medium layer

Umavathi, JC; Beg, OA

Abstract

The onset of double-diffusive (thermosolutal) convection in horizontal porous layer saturated
with an incompressible couple stress nanofluid saturated is studied with thermal conductivity
and viscosity dependent on the nanoparticle volume fraction. To represent the momentum
equation for porous media, a modified Darcy-Maxwell nanofluid model incorporating the
effects of Brownian motion and thermophoresis has been used. The thermal energy equation
includes regular diffusion and cross diffusion (Soret thermo-diffusion and Dufour diffusothermal) terms. A linear stability analysis depends on the normal mode technique and the
onset criterion for stationary and oscillatory convection is derived analytically. The nonlinear
theory based on the representation of the Fourier series method is applied to capture the
behavior of heat and mass transfer. It is found that the couple stress parameter enhances the
stability of the system in both the stationary and oscillatory convection modes. The viscosity
ratio and conductivity ratio both enhance heat and mass transfer. Transient Nusselt number is
found to be oscillatory when time is small. However, when time becomes very large, all the
three transient Nusselt number values approach to their steady state values.

Citation

Umavathi, J., & Beg, O. (2020). Modeling the onset of thermosolutal convective instability in a non-Newtonian nanofluid-saturated porous medium layer. Chinese Journal of Physics, 68, 147-167. https://doi.org/10.1016/j.cjph.2020.09.014

• Journal Article Type: Article
• Acceptance Date: Sep 15, 2020
• Online Publication Date: Sep 17, 2020
• Publication Date: Dec 1, 2020
• Deposit Date: Sep 16, 2020
• Publicly Available Date: Sep 17, 2021
• Journal: Chinese Journal Of Physics
• Print ISSN: 0577-9073
• Publisher: Elsevier
• Volume: 68
• Pages: 147-167
• DOI: https://doi.org/10.1016/j.cjph.2020.09.014
• Publisher URL: https://doi.org/10.1016/j.cjph.2020.09.014
• Related Public URLs: https://www.journals.elsevier.com/chinese-journal-of-physics/