Dual solutions of radiative Ag-MoS_2/water hybrid nanofluid flow with variable viscosity and variable thermal conductivity along an exponentially shrinking permeable Riga surface: Stability and entropy generation analysis
Gopinath Mandal, Dulal Pal
Abstract
In this analysis, the Silver-Molybdenum disulfide (Ag−MoS2)/water hybrid nanofluid flow past a permeable exponentially shrinking Riga surface with thermal radiant energy is considered. The novelty of this work is to find out the effects of variable viscosity, variable thermal conductivity with hybrid nanofluid’s slip velocity, and convective thermal boundary conditions over a shrinking Riga surface on velocity, temperature, skin-friction coefficient, Nusselt number, and entropy generation. The MATLAB programming platform with a fourth-order method to solve boundary value problem (bvp4c) was employed to get a good account of all pertinent flow parameters before solving the controlling partial differential equations numerically. Here 1% of Silver (Ag) and 1% of Molybdenum disulfide (MoS2) nanoparticles in the hybrid model are considered in the base fluid water. The basic achievement of this analysis is to explore the Nusselt number, skin friction coefficient along with entropy formation, and Bejan number. The irreversibility factor is calculated using the thermodynamics second law. The findings also point to the presence of dual-nature solutions in the shrinking sheet region for a given value of a high mass suction parameter, with a stable upper solution branch and unstable lower solution branch. Two solutions are found for the limited range of shrinking parameter λ when λc<λ and the solutions terminate at λ=λc in the shrinking region. Additionally, the first solution generates a positive minimum eigenvalue (β1>0), whereas the second solution generates a negative eigenvalue (β1<0), indicating the solution’s stability. Nusselt number is enhanced for variable viscosity parameter but diminished by variable thermal conductivity parameter for the stable solution. The entropy generation and the Bejan number both increase significantly with the increment of the thermal radiant-energy parameter, Biot number, and Eckert number. These results are crucial in the long term because they allow us to optimize heat transmission for cooling and heating applications. Hence, this investigation is incredibly significant in the present era, particularly in the automotive industry, home industry, paper plastics, ceramics, food packaging, food colorants, cancer treatment, cosmetics, pharmaceuticals, fabrics, paints, and soaps as well.