Forced convection heat transfer in Fe 3 O 4 -ethylene glycol nanofluid under the influence of Coulomb force

Forced convection heat transfer in Fe3O4-ethylene glycol nanofluid in a two-dimensional enclosure with Coulomb force is analyzed. Viscosity of the nanofluid is considered to be a function of the supplied voltage. The lid wall is taken into account as positive electrode. Control volume based finite element method (CVFEM) is used to obtain the flow and heat transfer characteristics. The effects of the Reynolds number (Re), the volume fraction of Fe3O4 (ϕ) and the supplied voltage (Δφ) are presented through graphs and tables, and are discussed. The numerical results show that the isotherms become dense on the lid wall with increasing values of Re and Δφ. However, the electric field is more effective at lower values of Re. Furthermore, the effect of electro-hydrodynamics is to increase the convention currents and the supplied voltage increases the temperature gradient. In the absence of electric field, we observe two vortexes in the streamlines and they rotate in the opposite directions. The upper one is counter clock wise vortex and it diminishes in the presence of Coulomb force. Also the Coulomb force helps in generating the thermal plume over the lid wall. As the Reynolds number increases, the strength of the vortexes increases. Furthermore, thermal plume is generated in the absence of an electric field. Isotherms are disturbed with an increase in the Coulomb force. Results indicate that the Coulomb force makes the upper vortex to disappear.