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Free convection of Fe3O4-Ethylene glycol nanofluid in existence of Coulomb forces is studied. Effect of thermal radiation is taken into account. Properties of nanofluid are varied with supplied voltage and shape of nanoparticles. The bottom wall is considered as positive electrode. Control Volume based Finite Element Method is used to obtain the results, which are the roles of Darcy number (Da), radiation parameter (Rd), Rayleigh number (Ra), nanofluid volume fraction (ϕ), and supplied voltage (Δφ). Results indicate that Nusselt number is an enhancing function of supplied voltage and Darcy number. Maximum values for temperature gradient are occurred for platelet shape nanoparticles.
One interesting active method for heat transfer augmentation is Electrohydrodynamic. Rarani et al.[1] reported good correlation for viscosity of nanofluid. Nanofluid has various applications in presence of various external forces. Heat transfer and pressure drop characteristics in the microchannel heat sink (MCHS) have been investigated by Liu et al.[2] They showed that interlaced microchannel leads to better heat transfer performance. Also they proved that pressure drop of the T-Y type microchannel is low. Kumar et al.[3] demonstrated radiative heat transfer of non-Newtonian nanofluid over a Riga sheet. Three-dimensional nanofluid flows was demonstrated by Sheikholeslami and Ellahi.[4] They illustrated that velocity detracts with augment of Lorentz forces. Sheikholeslami and Sadoughi[5] demonstrated water based nanofluid flow in presence of melting surface. Sheikholeslami and Shehzad[6] presented the influence of radiative mode on ferrofluid motion. They were taken into account variable viscosity. Nanofluid concentration has been reported by Hayat et al.[7] in existence of radiative mode. Kumar et al.[8] investigated Joule heating effect on nanofluid flow a rotating system. Sheikholeslami[9] investigated nanofluid EHD flow in a porous media. Sheikholeslami et al.[10] utilized mesoscopic method for nanofluid forced convection. Promvonge et al.[11] utilized V-finned twisted tapes in a duct to improve the thermal behavior. Influence of viscous dissipation on heat transfer in a circular micro-channel has been investigated by Liu et al.[12] Sheikholeslami and Seyednezhad[13] simulated nanofluid flow and natural convection in a porous media under the influence of electric field. Impact of variable Kelvin forces on ferrofluid motion was reported by Sheikholeslami Kandelousi.[14] Heat flux boundary condition has been utilized by Sheikholeslami and Shehzad[15] to investigate the ferrofluid flow in porous media. Sheikholeslami[16] investigated CuO-water nanofluid flow in a porous enclosure under the impact of Lorentz forces. In recent decade, various researcher published papers about heat transfer.[17–22]
This article intends to model the influence of thermal radiation on nanofluid behavior in existence of Coulomb forces via CVFEM. Roles of Darcy number, Rayleigh number, supplied voltage, radiation parameter and Fe3O4 volume fraction are presented in outputs.
Figure
The definition of electric field is[23]
knf can be expressed as:
So, the final PDE in existence of thermal radiation and electric field in porous media are:[20]
CVFEM uses both benefits of two common CFD methods. This method uses triangular element (see Fig.
Various mesh sizes have been tested to find the mesh independent result. Table
Influence of Coulomb forces on nanofluid natural convection heat transfer is reported considering thermal radiation. Nanofluid viscosity is a function of electric field. The porous enclosure is filled with Fe3O4 Ethylene glycol. Roles of Darcy number (Da = 10−2 to 102), Radiation parameter (Rd = 0 to 0.8), supplied voltage (Δφ = 0 to 6 kV), volume fraction of Fe3O4 (0% to 5%), Rayleigh number (Ra = 50 to 500) are depicted.
In order to find the influence of nanoparticles’ shape of heat transfer rate, a comparison has been reported in Table
Figures
Electric field effect on nanofluid natural convection in a porous cavity is simulated by means of CVFEM. Outputs are reported for various values of Rd, Da, Δφ, ϕ, and Ra. Outputs demonstrate that the distortion of isotherms becomes more with augment of Darcy number, radiation parameter, and Coulomb forces. As radiation parameter increases, temperature gradient near the hot wall enhances. Nusselt number has direct relationship with Darcy number, radiation parameter and Coulomb forces.
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