International Journal of Heat and Mass Transfer, Vol.134, 920-932, 2019
Oscillatory flows of electro-thermo-convection in eccentric annulus
A detailed numerical investigation for oscillatory electro-thermo-convection of dielectric liquids in horizontal eccentric annulus is carried out based on a unified lattice Boltzmann method (LBM). The liquid is under the simultaneous action of a strong unipolar charge injection and a thermal gradient. The self-oscillatory behaviors and heat transfer characteristics for different Rayleigh number Ra, electric Rayleigh number T, Prandtl number Pr, mobility parameter M and radii ratio are studied systematically. The results show that the values of Ra within the range from 10(3) to 10(4) have little effect on the periodic oscillatory convection, while the flow develops from steady to periodic oscillatory and finally evolves into chaotic as T increases, and the fundamental frequency and the fluctuation amplitude as well as the heat transfer rate increase with T. Moreover, it is found that the fluid properties have significant impact on the oscillatory convection, and the formation of oscillating flows is strongly related to the value of radius ratio. (C) 2019 Elsevier Ltd. All rights reserved.