Dielectrophoretic-driven thermoelectrohydrodynamic convection in a dielectric fluid layer induced by an inhomogeneous external electric field.

Abstract

This study examines the influence of an inhomogeneous external electric field on thermoelectrohydrodynamic (TEHD) convection and its impact on heat transfer enhancement in a dielectric fluid layer. TEHD convection arises when an external electric field interacts with a nonisothermal fluid, where electric field inhomogeneity is essential for convective flow. Such inhomogeneity can be intrinsically caused by temperature-dependent permittivity, ε(T), or geometrical curvature, such as in cylindrical or spherical shells. To investigate how an externally imposed inhomogeneous field modifies convective behavior compared to intrinsic effects, we employ an electrode configuration to generate field gradients between the top and bottom layers. Results reveal three distinct regimes based on the forcing intensity, characterized by the electric Rayleigh number, Ra_{E}. Convective motion is observed when Ra_{E}≠0, with significant heat transfer enhancement, surpassing prior studies. Specifically, the leading term of the Nusselt number, Nu, scales as Nu∼Ra_{E}^{0.3}.1The symbol ∼ means "scales as" throughout the article, not "order of magnitude." The prefactor and ranges are given in Eq. (20). These findings highlight the substantial potential of TEHD convection for improving heat transfer performance. The symbol ∼ means "scales as" throughout the article, not "order of magnitude." The prefactor and ranges are given in Eq. (20).