Lattice Boltzmann modeling of double-diffusive convection of dielectric liquid in rectangular cavity subjected to unipolar injection

Abstract

The lattice Boltzmann method is used to study the double-diffusive convection caused by the simultaneous effect of the temperature gradient and concentration gradient of the dielectric liquid in a rectangular cavity in the case of unipolar injection of ions. Considering that the physical model in this article is a complex dynamic system, we first conducted a linear stability analysis and obtained a neutral stability curve. Then we made a series of simulations to determine the influence of different dimensionless parameters on the movement of dielectric liquids and the distribution of charge density, temperature field, and concentration field. The variation range of the parameters is as follows: thermal Rayleigh number (1000≤Ra≤20000), electric Rayleigh number (100≤T≤800), Lewis number (1.0≤Le≤50.0), and buoyancy ratio (−2≤Nc≤0.5). The results show that the increase in electric Rayleigh number and thermal Rayleigh number will enhance the intensity of heat and mass transfer. Compared with pure electric convection, the existence of temperature field and concentration field have increased the instability of the dielectric fluid flow. When the Lewis number increases, the average Nusselt number will decrease but the average Sherwood number will increase. In addition, we noticed that the heat and mass transfer intensities have increased with the increase of the buoyancy ratio. When the buoyancy rate gradually increases from –2.0, we observe a bifurcation structure, and as the electric Rayleigh number increases, the critical value Ncc that causes convection will decrease.