Numerical investigation of injection-induced electro-convection in a dielectric liquid between two eccentric cylinders

Huang, Junyu; Selvakumar, R. Deepak; Guan, Yifei; Li, Hanqing; Traoré, Philippe; Wu, Jian

doi:10.1016/j.ijheatfluidflow.2020.108594

Cited by 13 publications

(3 citation statements)

References 47 publications

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“…Pérez et al (2009) numerically investigated the EHD flow between a blade injector and a flat plate by DNS. They studied the transition from laminar to chaotic flow with a varying electric Rayleigh number T. The EHD flow between two eccentric cylinders was numerically investigated by Huang et al (2020). The detailed bifurcation diagrams corresponding to different flow regimes were presented in terms of T. Their results indicated that the parameter eccentricity (the distance between the centres of outer and inner cylinders over the difference in the radii of two cylinders) influences the bifurcation.…”

Section: Stability Analysis Of Ehd Flowmentioning

confidence: 99%

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Numerical analyses of wire-plate electrohydrodynamic flows

Vázquez

Zhang

2023

J. Fluid Mech.

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We present numerical analyses of two-dimensional electrohydrodynamic (EHD) flows of a dielectric liquid between a wire electrode and two plate electrodes with a Poiseuille flow, using direct numerical simulation and global stability analysis. Both conduction and injection mechanisms for charge generation are considered. In this work we focused on the intensity of the cross-flow and studied the EHD flows without a cross-flow, with a weak cross-flow and with a strong cross-flow. (1) In the case without a cross-flow, we investigated its nonlinear flow structures and linear dynamics. We found that the flow in the conduction regime is steady, whereas the flow in the injection regime is oscillatory, which can be explained by a global stability analysis. (2) The EHD flow with a weak cross-flow is closely related to the flow phenomena in an electrostatic precipitator (ESP). Our analyses indicate that increasing the cross-flow intensity or the electric Reynolds number leads to a less stable flow. Based on these results, we infer that one should adopt a relatively low voltage and weak cross-flow in the wire-plate EHD flow to avoid flow instability, which may hold practical implications for ESP. (3) The case of strong cross-flow is examined to study the EHD effect on the wake flow. By comparing the conventional cylindrical wake with the EHD wake in linear and nonlinear regimes, we found that the EHD effect brings forward the vortex shedding in wake flows. Besides, the EHD effect reduces the drag coefficient when the cross-flow is weak, but increases it when it is strong.

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Section: Stability Analysis Of Ehd Flowmentioning

confidence: 99%

“…The EHD flow between two eccentric cylinders was numerically investigated by Huang et al. (2020). The detailed bifurcation diagrams corresponding to different flow regimes were presented in terms of .…”

Section: Introductionmentioning

confidence: 99%

Numerical analyses of wire-plate electrohydrodynamic flows

Vázquez

Zhang

2023

J. Fluid Mech.

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“…Results are presented in full or partial dimensional space, valid only within the given parameter space [23][24][25][26]. Our previous studies reported FVM-based numerical modeling and analysis of stability, flow, and heat transfer of conventional single-phase dielectric fluids under unipolar charge injection [33][34][35]. Likewise, we have also worked on the numerical modeling of nanofluids using different modeling approaches [36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of electrothermoconvection of a dielectric nanofluid in a heated cavity

Yang,

Peng,

Ramachandran

et al. 2024

Phys. Scr.

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A numerical analysis of electrohydrodynamic (EHD) flow and heat transfer of nanofluid in a heated rectangular cavity is presented. A two-dimensional (2D) rectangular cavity heated from the bottom is considered. An electric potential difference is applied vertically, with the bottom wall acting as a high-voltage electrode, and the top wall is grounded. TiO2-25# transformer oil nanofluid with nanoparticle volume fraction ranging from 0 - 5% is considered. The numerical model for EHD flow and heat transfer of nanofluid is implemented in the finite-volume method (FVM) based numerical framework of OpenFOAM. A single-phase approach based on the effective properties is adopted to model the nanofluids. A two-way coupled EHD flow model is employed to consider mutual interactions of flow and electric field variables. The flow and heat transfer behavior of nanofluids in the presence of an electric field is quantified with reference to the key parameters, electric Rayleigh number (T), and the nanoparticle volume fraction φ. The addition of nanoparticles increased the viscosity and marginally reduced the natural convective flow and heat transfer. However, EHD flow induced by the electric field aided in overcoming the weak natural convection flow in nanofluids. Results confirm that nanofluids' net effective heat transfer rates are notably increased in the presence of the electric field. For the parameters under consideration, combining electric fields with nanofluids led to a significant heat transfer enhancement of up to 32.3%. The present study showcases the feasibility of combining passive heat transfer enhancement using nanoparticles and active heat transfer enhancement using EHD flow.

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Magnetohydrodynamic Effects on Double Diffusion of Non‐Newtonian Hybrid Nanofluid in Circular Eccentric Annuli

Supti,

Molla,

Nag

et al. 2024

Engineering Reports

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The numerical investigation conducted in this study focuses on the heat and mass transfer in magnetohydrodynamic non‐Newtonian power‐law fluid flow of temperature‐dependent Al2O3–Fe3O4–water hybrid nanofluid within cylindrical annuli across four different eccentricities. This type of problem finds widespread application in various engineering contexts, where hybrid non‐Newtonian fluids offer enhanced efficiency for cooling and insulation purposes. In this configuration, the inner circle of the geometry is hot while the outer circle is cold, with the nanofluid filling the space between the cylinders. The governing equations are simulated using the Galerkin weighted residual finite element method. Various parameters are controlled in the study, including the Rayleigh number ranging from to , power‐law index ranging from to , nanoparticle volume fraction ranging from to , Hartmann number ranging from to , Buoyancy ratio ranging from to , and Lewis number ranging from to , in addition to the fixed Prandtl number (6.8377). The study presents visualizations such as streamlines, isotherms, and iso‐concentration contours, along with the assessment of heat and mass transfer rates expressed in terms of Nusselt and Sherwood numbers. The findings reveal that the heat transfer rate increases with higher nanoparticle volume fraction, Rayleigh number, and Buoyancy ratio. Similarly, the mass transfer rate is enhanced with increased Rayleigh number, Lewis number, and power‐law index. Notably, elevating the power‐law index leads to a decrease of 50.1% in the local Nusselt number and 52.4% in the local Sherwood number, respectively. With and , increasing from to raises and .

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Numerical investigation of injection-induced electro-convection in a dielectric liquid between two eccentric cylinders

Cited by 13 publications

References 47 publications

Numerical analyses of wire-plate electrohydrodynamic flows

Numerical analyses of wire-plate electrohydrodynamic flows

Numerical analysis of electrothermoconvection of a dielectric nanofluid in a heated cavity

Magnetohydrodynamic Effects on Double Diffusion of Non‐Newtonian Hybrid Nanofluid in Circular Eccentric Annuli

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