Electrohydrodynamic natural convection enhancement for horizontal axisymmetric bodies

This article addresses a new theoretical derivation to describe the electrohydrodynamic (EHD) natural convection enhancement for isothermal, horizontal axisymmetric bodies immersed in a dielectric liquid under the effects of uniform electric fields. Using asymptotic power series expansions in the laminar boundary-layer regime we obtain convenient explicit relations which are capable of predicting the local and average Nusselt numbers in terms of two controlling parameters, namely the Rayleigh number and the electric Rayleigh number. The solutions of two coupled partial differential equations for the temperature and the stream function are represented by Gortler-type series, which are universal with respect to body contours. The Gortler-type series appears to converge rapidly so that minimal computational effort is required even for a sub-class of body shapes that do not admit the usual similarity transformations. As an example, the leading order approximation for the first derivative of the temperature is used to calculate the local and total average Nusselt numbers for horizontal circular cylinders.

► New approach to investigate electrohydrodynamic natural convection enhancement.
► Isothermal axisymmetric bodies in dielectric liquids under external electric fields.
► Universal expressions including body shapes admitting no similarity transformations.
► The predicted average Nusselt number cannot be expressed as usually suggested.
► Natural convection enhancement for horizontal circular cylinders is discussed.