Electro-thermo-convection in non-Newtonian power-law fluids within rectangular enclosures

Electro-thermo-convection is a typical interdisciplinary problem, that has been widely studied in terms of its physical phenomena in Newtonian fluids. As an essential supplement to the study of electrohydrodynamics, electro-thermo-convection in power-law fluids within rectangular enclosures is investigated in this paper. Two geometrical configurations are considered, namely differentially heated vertical and horizontal wall configurations. The governing equations are discretized using the finite volume scheme, and the bifurcations, flow patterns, and heat transfer efficiency under different power-law indexes are studied. A comprehensive comparison between the Newtonian and non-Newtonian cases is presented. The results indicate that electro-thermo-convection in power-law fluids exhibits more complicated hydrodynamic behavior than in Newtonian fluids. The shear-thinning characteristic decreases the criterion of subcritical bifurcation and corresponds to a smaller hysteresis loop, whereas the shear-thickening characteristic has an opposite effect. The bifurcation diagrams exhibit various features under different power-law indexes, and some of which have not been observed in Newtonian fluids. Additionally, the effects of the non-Newtonian behavior on the temporal evolution of the flow are discussed, and the fluid motion is found to be sensitive to the power-law index.