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A convection‐diffusion‐reaction scheme is proposed in this study to simulate the high gradient electroosmotic flow behavior in microchannels. The equations governing the total electric field include the Laplace equation for the effective electrical potential and the Poisson‐Boltzmann equation for the electrical potential in the electric double layer.

Mixed electroosmotic/pressure‐driven flow in a straight microchannel is studied with the emphasis on the Joule heat in the equations of motion. The nonlinear behaviors resulting from the hydrodynamic, thermal and electrical three‐field coupling and the temperature‐dependent fluid viscosity, thermal conductivity, electrical permittivity, and conductivity of the investigated buffer solution are analyzed.

The solutions computed from the employed flux discretization scheme for the hydrodynamic, thermal and electric field equations have been verified to have good agreement with the analytical solution. Parametric studies have been carried out by varying the electrical conductivity at the fixed zeta potential and varying the zeta potential at the fixed electrical conductivity.

Investigation is also addressed on the predicted velocity boundary layer and the electric double layer near the negatively charged channel wall.

Introduces the fourth and final chapter of the ISEF 1999 Proceedings by stating electric and magnetic fields are influenced, in a reciprocal way, by thermal and mechanical fields. Looks at the coupling of fields in a device or a system as a prescribed effect. Points out that there are 12 contributions included ‐ covering magnetic levitation or induction heating, superconducting devices and possible effects to the human body due to electric impressed fields.

To determine the electrical field E₁(t) in spherical and cylindrical gas voids existing in an insulator by considering surface conductivity of gas voids having an electrical permittivity of ε₁ and conductivity of γ₁ for DC and AC situations.

Analytical expressions satisfying Laplace equation for inside and outside of the cylindrical and spherical gas voids in an insulator located in an external electrical field having a definite time dependent character, have been derived by considering the surface conductivity of the gas void. The coefficients included by these analytical expressions have been determined by utilizing the continuity equation of the current on the surface of the voids.

It has been demonstrated that the electrical field remains uniform in spherical and cylindrical gas voids when the surface conductivity of gas void has been considered. It has been determined that the contact charging process of different shaped particles has an exponential characteristic, and some expressions have been derived to determine the time constants of this process for practical purposes.

The results have been applied to the problems about contact charging of semi‐spherical and semi‐cylindrical insulated particles located at a charged surface and problems about the calculation of onset discharging voltage of ionization process in dielectric including gas voids.

For spherical and cylindrical gas voids, the onset discharging voltage corresponding to the ionization process occurring in gas voids has increased by increasing the surface conductivity of the void. For the limit value of the surface conductivity, the voids in the insulator behaves like metal particles distributed into the insulator, for this reason, at the outside of the void, especially in the regions where the voids are close to the electrodes and each other, the electrical field will be non‐uniform and will increase. This situation will cause the ignition of the partial discharge and destroy to the insulator.

THE electric current is often compared, especially in “ popular ” works, to the flow of water in a pipe. This conception holds good in certain respects, but is definitely misleading in many ways. The ground engineer who wishes to obtain the “ X ” licence for electrical equipment need not, it is true, make such a close study of the fundamentals of electricity and magnetism as the electrical engineer or science degree student would have to do. Nevertheless, in order to understand the operation and maintenance of electrical apparatus, however simple, some theoretical knowledge is necessary. In electrical work, the beginner is confronted with one special difficulty—the absence of moving parts—and this difficulty seems to be most formidable to men who have been accustomed in their daily work to think in terms of crank‐shafts, gear‐wheels, cams, valves, push‐rods and all the other apparatus of mechanical engineering. To put the situation into a phrase, the beginner wants to “ see the wheels go round,” and is naturally somewhat baffled when he discovers that there are no wheels to go round. Some imagination is, therefore, necessary in studying electrical phenomena, and the student, particularly the engine fitter, must school himself to avoid the futile applica‐tion of well‐absorbed mechanical principles to apparatus in which they have no application.

The purpose of the paper is to present a three-dimensional model and analyze the internal link between surface potential distribution and the electrical activity of lumbar muscles with finite element method.

Finite element method.

The simulated results have shown that there is a significant difference of surface potential topography patterns between low back pain (LBP) patients and normal healthy control. The normal shows symmetrical in contrast with the asymmetrical LBP pattern.

It provides a new view to analyze lumbar muscle activity with finite element method, which has a potential clinical application on lumbar muscle function analysis and LBP rehabilitation assessment.

Finite difference method (FDM) is a very useful and simple tool in determining electrical potential field of two‐dimensional geometries, such as integrated circuit (IC) planar resistors. It is very accurate and its accuracy can be easily controlled by changing the grid size. One limitation of the FDM, however, is that it computes potentials at predetermined grid points only. Unlike the finite element method (FEM), it does not compute potential functions that can be used to interpolate potentials at the points that are not located at the grid, or to use these functions in determining other quantities based upon the computed potential such as electric field intensity. This paper describes a method that is a combination of the FDM and FEM. It retains the simplicity and accuracy of the FDM. Yet, like the FEM, it provides potential functions that can be used for interpolation and post‐processing of potential. The combined FDM‐FEM method is used to determine the potential functions of an IC planar resistor. The results are in agreement with analytically derived results. The approach we have developed is simple yet accurate and thus of use in professional engineering work.

This paper aims to study the heat transfer of nanofluid flow driven by the move of channel walls in a microchannel under the effects of the electrical double layer and slippery properties of channel walls. The distributions of velocity, temperature and nanoparticle volumetric concentration are analyzed under different slip-length. Also, the variation rates of flow velocity, temperature, concentration of nanoparticle, the pressure constant, the local volumetric entropy generation rate and the total cross-sectional entropy generation are analyzed.

A recently developed model is chosen which is robust and reasonable from the point of view of physics, as it does not impose nonphysical boundary conditions, for instance, the zero electrical potential in the middle plane of the channel or the artificial pressure constant. The governing equations of flow motion, energy, electrical double layer and stream potential are derived with slip boundary condition presented. The model is non-dimensionalized and solved by using the homotopy analysis method.

Slip-length has significant influences on the velocity, temperature and nanoparticle volumetric concentration of the nanofluid. It also has strong effects on the pressure constant. With the increase of the slip-length, the pressure constant of the nanofluid in the horizontal microchannel decreases. Both the local volumetric entropy generation rate and total cross-sectional entropy generation rate are significantly affected by both the slip-length of the lower wall and the thermal diffusion. The local volumetric entropy generation rate at the upper wall is always higher than that around the lower wall. Also, the larger the slip-length is, the lower the total cross-sectional entropy generation rate is when the thermal diffusion is moderate.

The findings in this work on the heat transfer and flow phenomena of the nanofluid in microchannel are expected to make a contribution to guide the design of micro-electro-mechanical systems.

This paper aims to focus on the finite element method in the frequency domain (FD-FEM) for the transient electric field in the non-sinusoidal steady state under the non-sinusoidal periodic voltage excitation.

Firstly, the boundary value problem of the transient electric field in the frequency domain is described, and the finite element equation of the FD-FEM is derived by Galerkin’s method. Secondly, the constrained electric field equation on the boundary in the frequency domain (FD-CEFEB) is also derived, which can solve the electric field intensity on the boundary and the dielectric interface with high accuracy. Thirdly, the calculation procedures of the FD-FEM with FD-CEFEB are introduced in detail. Finally, a numerical example of the press-packed insulated gate bipolar transistor under the working condition of the repetitive turn-on and turn-off is given.

The FD-CEFEB improves numerical accuracy of electric field intensity on the boundary and interfacial charge density, which can be achieved by modifying the existing FD-FEMs’ code in appropriate steps. Moreover, the proposed FD-FEM and the FD-CEFEB will only increase calculation costs by a little compared with the traditional FD-FEMs.

The FD-CEFEB can directly solve the electric field intensity on the boundary and the dielectric interface with high accuracy. This paper provides a new FD-FEM for the transient electric field in the non-sinusoidal steady state with high accuracy, which is suitable for combined insulation structure with a long time constant.

This paper aims to present a fully coupled thermo-electrical finite-element battery model with an applied model-order reduction. The model is used to analyse the thermal design of battery modules during typical drive-cycles of electric vehicles.

A model-order reduction is applied, in which the electrical linear bus-bars are analysed in an a-priori step. For these bus-bars, special distributed basis-functions are computed, which make the solution of differential Ohm's law unnecessary during the transient simulation. Furthermore, the distributed basis-functions are used to strongly couple the non-linear battery models, which reduces the iterations needed to simulate them.

Altogether, this results in a fast simulation scheme for coupled linear and non-linear electrical components and their thermal behaviour.

The presented method delivers an innovative approach, on how to systematically minimize the computational effort in a system of linear and non-linear electrical components, while keeping the full three-dimensional information of the original problem.

The characteristics of fluid motions in micro-channel are strong fluid-wall surface interactions, high surface to volume ratio, extremely low Reynolds number laminar flow, surface roughness and wall surface or zeta potential. Due to zeta potential, an electrical double layer (EDL) is formed in the vicinity of the wall surface, namely, the stern layer (layer of immobile ions) and diffuse layer (layer of mobile ions). Hence, its competent designs demand more efficient micro-scale mixing mechanisms. This paper aims to therefore carry out numerical investigations of electro osmotic flow and mixing in a constricted microchannel by modifying the existing immersed boundary method.

The numerical solution of electro-osmotic flow is obtained by linking Navier–Stokes equation with Poisson and Nernst–Planck equation for electric field and transportation of ion, respectively. Fluids with different concentrations enter the microchannel and its mixing along its way is simulated by solving the governing equation specified for the concentration field. Both the electro-osmotic effects and channel constriction constitute a hybrid mixing technique, a combination of passive and active methods. In microchannels, the chief factors affecting the mixing efficiency were studied efficiently from results obtained numerically.

The results indicate that the mixing efficiency is influenced with a change in zeta potential (ζ), number of triangular obstacles, EDL thickness (λ). Mixing efficiency decreases with an increment in external electric field strength (Ex), Peclet number (Pe) and Reynolds number (Re). Mixing efficiency is increased from 28.2 to 50.2% with an increase in the number of triangular obstacles from 1 to 5. As the value of Re and Pe is decreased, the overall percentage increase in the mixing efficiency is 56.4% for the case of a mixing micro-channel constricted with five triangular obstacles. It is also vivid that as the EDL overlaps in the micro-channel, the mixing efficiency is 52.7% for the given zeta potential, Re and Pe values. The findings of this study may be useful in biomedical, biotechnological, drug delivery applications, cooling of microchips and deoxyribonucleic acid hybridization.

The process of mixing in microchannels is widely studied due to its application in various microfluidic devices like micro electromechanical systems and lab-on-a-chip devices. Hence, its competent designs demand more efficient micro-scale mixing mechanisms. The present study carries out numerical investigations by modifying the existing immersed boundary method, on pressure-driven electro osmotic flow and mixing in a constricted microchannel using the varied number of triangular obstacles by using a modified immersed boundary method. In microchannels, the theory of EDL combined with pressure-driven flow elucidates the electro-osmotic flow.