Chemical reaction influence on nanofluid flow in a porous layer: Stability analysis. (November 2022)

• Record Type: Journal Article
• Authors: Umavathi, J.C.; Sheremet, M.A.
• Is Part Of: International communications in heat and mass transfer. Volume 138(2022)
• Publication Date: 2022-11
• Subjects: Thermo-solutal convection -- Stability -- Nanofluid -- Exothermic reaction -- Frank–Kamenetskii thermal ignition -- Porous medium -- Brownian motion -- Thermophoresis; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Heat -- Transmission; Mass transfer; Periodicals; 621.4022
• DOI: 10.1016/j.icheatmasstransfer.2022.106353
• Languages: English
• ISSNs: 0735-1933

Abstract

Abstract: An influence of exothermic chemical reaction on the natural thermo-solutal convection in a horizontal channel filled with sparsely packed permeable nanofluid is investigated. It is assumed that the fluid viscosity is different from the effective viscosity. The Brinkman approach is engaged for the porous material, while the nanofluid approach features the Buongiorno model. To figure out the stability of the linear terms, normal mode analysis is opted. Galerkin technique is selected to work out the nonlinear terms. The Rayleigh number and its relevant wave numbers are assessed for all dimensionless parameters and exposed in the form of graphs. It is found that there is a critical value of Frank–Kamenetskii number at which the system is most unstable. It is found that increasing the viscosity ratio delays the onset of convection. With exothermic chemical reactions, the fluid in the porous medium is more prone to instability as compared to the case in which chemical reactions are absent. A critical value of Frank–Kamenetskii number is also identified at which the system is most unstable, and this is shown to be independent of both porous media parameter and the viscosity ratio. Applications of the study arise in nano-doped geothermal energy extraction, chemical and bio reactors and other engineering systems. Highlights: An influence of exothermic chemical reaction on the natural convection in a nanofluid-saturated sandwich porous layer is investigated. The Brinkman approach is used for the porous medium, while the Buongiorno model defines the nanofluid transport parameters. Galerkin method is used for description of the nonlinear terms. The onset of convection can be delayed with a growth of the viscosity ratio. An addition of nanoparticles augments the stability of the regime.