Effect of electrical field on buoyancy-induced flows in an enclosure

EHD-enhanced heat transfer is numerically examined for laminar natural convection in an enclosure with differentially heated vertical walls. Attention is also focused on the effect of added electric field on the flow stability. The electrical field is generated by positive corona from a wire electrode located at the center of the enclosure and charged with a high DC voltage (10⩽V₀ ⩽17.5 kV). The thermal buoyancy effects considered are in the range of 10³<Ra⩽10⁶. For a given Rayleigh number, the flow and temperature fields change from a steady state to periodic and nonperiodic convection as the applied voltage increases. It is found that heat transfer enhancement increases with the applied voltage but decreases with the Rayleigh number. Due to the existence of secondary flows, there is an improvement in heat transfer and is most significant for flows at a small Rayleigh number