Electrohydrodynamic flow of dielectric liquid around a wire electrode - effect of truncation of onsager function

Fernandes, Dolfred Vijay; Cho, D.; Suh, Yong Kweon

doi:10.1109/tdei.2014.6740740

Cited by 13 publications

(8 citation statements)

References 25 publications

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“…Coulomb force causes by using the electric field on positive and negative charges and its effect appears in the dielectric fluid movement. The electric scalar potential φ is used to calculate the electric field: and the Poisson equation is used to govern the distribution of φ : where ε is the fluid electrical permittivity and ρ c is the density of space charge determined as below (Fernandes et al , 2014): Where n and p are negative and positive charge densities, in turn. The mechanisms for transporting these charges and equilibrium between recombination of ions and dissociation are explained in Nourdanesh et al (2020).…”

Section: Analytical Designmentioning

confidence: 99%

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Introduction of a novel electric field-based plate heat sink for heat transfer enhancement of thermal systems

Nourdanesh

Ranjbar

2021

HFF

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Purpose The purpose of this study is to use an electric field technique to design novel heat sinks capable of rejecting as much heat as possible in a limited space. Configuration of electrodes in this study can be used for increasing the efficiency of heat sinks. Design/methodology/approach This study investigates a novel electrohydrodynamic (EHD)-based heat sink for thermal management of electronic devices and thermal systems. The significant part of designing an EHD heat sink is the arrangement of the electrodes. A numerical simulation is performed for a heat sink with two parallel plates to determine the optimum dimensional configuration of electrodes. The upper plate of this heat sink is the ground electrode with a constant atmosphere temperature, and the lower plate of it with flush-mounted high-voltage electrodes has uniform heat flux. Findings The results show that heat transfer changes by the size of the vortices and the number of them. These vortices are emerged by the electric field, and the number of them increases with increasing the number of electrodes. The interaction of vortices size and number leads to having the lowest average temperature in the optimum case by two high voltage electrodes with widths of 7.5 mm and a 17.5 mm gap between them. In comparison with the case without the electric field, with increasing the applied voltage to 30 kV, the efficiency of this EHD heat sink increases up to 37%. Originality/value Improvements in electrical equipment make them more compact with higher heat fluxes. Hence, the amount of heat to be dissipated per area increases and needs thermal management to operate at their design temperatures. Therefore, to improve the performance and life span of electronic components and increase their efficiency, it is necessary to design heat sinks to decrease their maximum (peak) temperature.

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Section: Analytical Designmentioning

confidence: 99%

“…where « is the fluid electrical permittivity and r c is the density of space charge determined as below (Fernandes et al, 2014):…”

Section: Theoretical Model Of Electrohydrodynamic Heat Sinkmentioning

confidence: 99%

Introduction of a novel electric field-based plate heat sink for heat transfer enhancement of thermal systems

Nourdanesh

Ranjbar

2021

HFF

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“…However, local variation of the field intensity leads to a nonzero gradient of the ion concentrations, which then causes a relatively small amount of concentration difference between the cation and anion, corresponding to nonuniform field–induced space charge density. The space charge density can be given by the formula q = − K Ε ⋅ ∇ E ( 31 – 33 , 35 , 37 – 38 ), where K = 2ε 0 ε r γ > 0 is a constant (ε 0 and ε r are the vacuum permittivity and the relative permittivity of the liquid, respectively, and γ is the Onsager constant). Thus, it is obvious from this equation q = − K Ε ⋅ ∇ E that space charge density is determined by electric field Ε and its gradient ∇ E .…”

Section: Resultsmentioning

confidence: 99%

“…Under the Coulomb force (F = Εq = − K(Ε ⋅ ∇E)Ε), the space charges will migrate from the rod positive electrode along the electric field line. During this process, the migration of space charges will drag the dielectric liquid flow (31)(32)(33)(34)(35)(38)(39)(40), that is, ECF jet. The ECF jet will generate the actuation force.…”

Section: Resultsmentioning

confidence: 99%

Self-contained soft electrofluidic actuators

et al. 2021

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Soft robotics revolutionized human-robot interactions, yet there exist persistent challenges for developing high-performance soft actuators that are powerful, rapid, controllable, safe, and portable. Here, we introduce a class of self-contained soft electrofluidic actuators (SEFAs), which can directly convert electrical energy into the mechanical energy of the actuators through electrically responsive fluids that drive the outside elastomer deformation. The use of special dielectric liquid enhances fluid flow capabilities, improving the actuation performance of the SEFAs. SEFAs are easily manufactured by using widely available materials and common fabrication techniques, and display excellent comprehensive performances in portability, controllability, rapid response, versatility, safety, and actuation. An artificial muscle stretching a joint and a soft bionic ray swimming in a tank demonstrate their effective performance. Hence, SEFAs offer a platform for developing soft actuators with potential applications in wearable assistant devices and soft robots.

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“…1,2 The use of electrohydrodynamics (EHD), where a voltage is applied to induce the flow of a working fluid, may help reduce the size of actuators. 3 In EHD, three forces are known to act directly on a fluid (unlike in electrophoresis where the forces act on dispersed particles in a fluid).…”

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confidence: 99%

Electrohydrodynamic Conduction Pump with Asymmetrical Electrode Structures in the Microchannels

Sato

Yamanishi

Cacucciolo³

et al. 2017

Chem. Lett.

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In this study, we have developed a microfluidic pump that utilizes the electrohydrodynamic (EHD) conduction of a working fluid. Ring-shaped pumps have been used in previous studies on EHD conduction, but these require a three-dimensional arrangement of electrode pairs, which makes it difficult to downsize the apparatus. Here, we propose a mechanism to achieve one-way fluid flow in the microchannels by arranging non-parallel electrodes in a plane to generate an asymmetric electric field. One advantage of this design is that it can be easily and precisely fabricated using microelectromechanical system (MEMS) processing techniques: this has allowed us to integrate a micropump and a microchannel into a single device. Moreover, the pressure generated by the pump is induced solely by electrochemical reactions; since mechanical components such as gears are not required, this helps reduce the noise generated by the device. The demand for small actuators is increasing due to the development of highly integrated electronics and the miniaturization of devices.1,2 The use of electrohydrodynamics (EHD), where a voltage is applied to induce the flow of a working fluid, may help reduce the size of actuators.3 In EHD, three forces are known to act directly on a fluid (unlike in electrophoresis where the forces act on dispersed particles in a fluid). These forces can be described by eq 1.Here, F is the electric body force, µ e is the charge density, E is the electric field magnitude, E is the electric field, ¾ is the permittivity, and µ is the mass density. The first term in the equation represents the Coulomb force acting on free charges in an electric field. The second and third terms represent the dielectrophoretic and electrostriction forces, respectively, which are polarization forces acting on polarized charges. The dielectrophoretic force acts on a permittivity gradient and does not exist for isothermal singlephase flow, and the electrostriction force is only applicable to compressible fluids. EHD phenomena can be divided into EHD conduction and EHD injection. It is known that EHD conduction occurs at less than 10 7 V m ¹1 . 4 EHD injection can produce large pressures, but can also lead to deterioration of the electrodes. Electrode deterioration is not a major issue for EHD conduction, and therefore this has attracted more research interest. Pearson and Seyed-Yagoobi have described the mechanism of EHD conduction as follows.5 When a high-voltage electric field is applied to a fluid, an equilibrium is achieved between the dissociation of some of the neutral species, AB, into ions (A + and B ¹ ), and recombination of the ions back into AB.When the voltage is increased above a certain threshold value, the rate of dissociation becomes faster than the rate of recombination, and the ions A + and B ¹ are attracted to the electrodes. As a result, the ions collide with the neutral AB species, and the fluid flows towards the electrodes.When EHD conduction is used for pumping, it is important to generate unidirectional flow by break...

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Electrohydrodynamic flow of dielectric liquid around a wire electrode - effect of truncation of onsager function

Cited by 13 publications

References 25 publications

Introduction of a novel electric field-based plate heat sink for heat transfer enhancement of thermal systems

Introduction of a novel electric field-based plate heat sink for heat transfer enhancement of thermal systems

Self-contained soft electrofluidic actuators

Electrohydrodynamic Conduction Pump with Asymmetrical Electrode Structures in the Microchannels

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