Bifurcation analysis of combined double-diffusive natural convection and thermal radiation under a non-uniform magnetic field in a wavy enclosure

Abstract

In the current work, the bifurcation phenomenon of a double-diffusive natural convection flow is analyzed for a non-uniform magnetic field applied to a wavy enclosure in the presence of radiation, for the first time. The finite volume method has been utilized to simulate volumetric radiation. To solve the continuity, momentum, energy, and species equations, the multiple-time relaxation lattice Boltzmann technique is adopted. In addition, the immersed boundary approach has been applied to identify the complex boundaries inside the Cartesian coordinates system. The effects of specific pertinent parameters, including the optical thickness (0.1≤τ≤100), Buoyancy ratio (-5≤N≤5), Rayleigh number (104≤Ra≤105), wave amplitude (0≤λ≤0.2), and Hartmann number (0≤Ha≤50) on thermohydrodynamic characteristics of the system have been investigated. The results indicated that an increase in Hartmann number disappears the bifurcation phenomenon. In addition, it was observed that the initial condition of hot temperature and high concentration leads to instability in the flow. In the radiation case for λ>0.1, 5<τ<30, and 15≤Ha≤30, the flow appears unsteady. Bifurcation occurs in all values of wavy amplitude, and optical thickness studied. Heat and mass transfers decrease when the initial condition is cold temperature and low concentration. Also, Radiation does not affect the critical Rayleigh number.