Transition sequences and heat transfer enhancement in electro-thermo-convection of a dielectric liquid between two parallel electrodes

Transition sequences with various flow patterns and heat transfer enhancement of a dielectric liquid layer between two parallel planar electrodes of infinite length are investigated numerically. External electric field and internal temperature field are considered to be two independent driving factors of the flow, while unipolar charge injection via the heated bottom electrode acts as a single source of free charges. The results show that three different types of transition sequences are observed with the increase of Rayleigh number, namely, the alternating periodic-chaotic sequence, the quasi-periodic sequence, and the altered quasi-periodic sequence. Electric field can significantly enhance the convective heat transfer of the system. The enhancement rate due to the electric field measured by a Nusselt number ratio is larger at smaller Rayleigh numbers. Within the range of selected parameters, the maximum Nusselt number obtained is 8.3, and the maximum heat transfer enhancement ratio is 4.1.