Double-diffusive convection flow with Soret and Dufour effects in an irregular geometry in the presence of thermal radiation

In this study, the effect of radiation on double-diffusive natural convection is investigated by considering the phenomena of Soret and Dufour in complex geometry, for the first time. The multi-time relaxation lattice Boltzmann method has been adopted to calculate the momentum, energy, and species equations. The radiative transfer equation has been solved using the finite volume method. Complex boundaries have been simulated by the sharp interface-immersed boundary method. The influences of effective parameters including the optical thickness (tau = 1 to 100), Rayleigh number (Ra = 104 and 105), Planck number (Pl = 0.01 to 1), Buoyancy ratio (Br = - 5 to 5), Soret number (Sr = - 1 to 1), and Dufour number (Df = - 1 to 1) have been analyzed on the flow field, heat, and mass transfer in a square cavity with an internal circular cylinder. Moreover, temporal variations of velocity and phase space trajectory have been used to study the effects of radiation on unsteady flow behavior. Results indicate that, the increment in optical thickness significantly reduces radiation, while a sweep behavior occurs in mass and heat transfer. Increasing the Dufour (Soret) parameter depending on the value of the Soret (Dufour) parameter can increase or decrease the mass (heat) transfer.