Electrohydrodynamically Enhanced Forced Convection in a Horizontal Channel by Nonsymmetric Electric Field

Abstract

The present study investigates heat transfer enhancement of forced convection in a horizontal channel by nonsymmetric electric field. The electrical field is generated from a wire electrode charged at a high voltage of direct current with a positive polarity. Numerical calculations have covered a wide range of parameters (that is, , 15, and 18 kV; and ). The previous studies with a symmetrical electric field have reported that the resulting flow and temperature fields may become oscillatory under certain operating conditions. In contrast, the present study only observes steady flow and temperature fields due to a weaker electric field. However, the present results are consistent with those of the previous studies that heat transfer enhancement increases with the applied voltage but decreases with the Reynolds number. At a low Reynolds number, it is observed that the electric field significantly perturbs the flow and temperature fields, thus leading to an increase in heat transfer. When the Reynolds number is sufficiently increased, the electric field is suppressed and leads to a diminishing effect on the heat transfer enhancement. Most importantly, the present study has shown that heat transfer enhancement by an asymmetric electric field is more effective than that by a symmetric one.