Numerical calculation of electric fields, losses and interfacial charge densities in water-treed dielectric composite structure

2004 ◽  
Vol 61 (3-4) ◽  
pp. 171-187
Author(s):  
Yuriy V. Serdyuk ◽  
Aleksandr D. Podoltsev ◽  
Stanislaw M. Gubanski
Keyword(s):  
Numerical Calculation ◽  
Electric Fields ◽  
Composite Structure ◽  
Charge Densities ◽  
Dielectric Composite ◽  
Interfacial Charge

Interfacial charge dynamics in multi-dielectrics under various electric fields and thermal gradient

2020 ◽  
Author(s):  
Mohamadreza Arab Baferani ◽  
Chuanyang Li ◽  
Tohid Shahsavarian ◽  
Mattewos Tefferi ◽  
Ivan Jovanovic ◽  
...  
Keyword(s):  
Electric Fields ◽  
Thermal Gradient ◽  
Charge Dynamics ◽  
Interfacial Charge

scholarly journals Charge Densities above Pulsar Polar Caps

2000 ◽  
Vol 177 ◽  
pp. 463-464
Author(s):  
A. Jessner ◽  
H. Lesch ◽  
Th. Kunzl
Keyword(s):  
Neutron Star ◽  
Electric Field ◽  
Work Function ◽  
Potential Barrier ◽  
Electric Fields ◽  
Surface Potential ◽  
Thermal Emission ◽  
Equilibrium Density ◽  
Charge Densities ◽  
Polar Caps

A simplified model provided the framework for our investigation into the distribution of energy and charge densities above the polar caps of a rotating neutron star. We assumed a neutron star withm= 1.4M⊙,r= 10km, dipolar field |B0| = 1012G,B||Ω and Ω = 2Π · (0.5s)−1. The effects of general relativity were disregarded. The induced accelerating electric fieldE||reachesE0= 2.5 · 1013V m−1at the surface near the magnetic poles. The current density along the field lines has an upper limitnGJ, when the electric field of the charged particle flow cancels the induced electric field: At the polesnGJ(r=rns,θ= 0) = 1.4 · 1017m−3.The work function(surface potential barrier)EWis approximated by the Fermi energyEFof magnetised matter. Following Abrahams and Shapiro (1992) one needs to revise the surface density from the canonical 1.4 · 108kg m−3down toρFe = 2.9 · 107kg m−3. Withwe obtain a value ofEF=Ew= 417eV. There are two relevant particle emission processes:Field (cold cathode) emissionby quantum-mechanical tunneling of charges through the surface potentialandthermal emissionwhich is a purely classical process. In strong electric fields it is enhanced by the lowering of the potential barrier due to the Schottky effect. The combined Dushman-Schottky equationwithtells us, thatat temperatures> 2 · 105K the the Goldreich-Julian current can be supplied thermal emission alone. The surface temperature however has a lower limit in the order of 105K due to the rotational braking. Therefore, in most cases a sufficient supply of charges for the Goldreich-Julian current is available and the electrical field accelerating the particles will be quenched as a result of their abundance. Otherwise a residual equilibrium electric field Eeqremains with:and hence the equilibrium density is:n=nfieid(Eeq,EW) +nDS(Eeq,EW,T) For a temperature just below the onset of thermal emission (T= 1.85 · 105K) the charge density is found to vary almost linearly with the work functionEWfor values ofEWbetween 0.3 and 2 keV. At the chosen value forEWof 417 eVthe residual electric field amounts to only 8.5% of the vacuum value. Even in the residual electric field the particles are rapidly accelerated to relativistic energies balanced by inverse Compton and curvature radiation losses.

scholarly journals Mapping atomic electric fields and charge densities by four-dimensional STEM

2017 ◽  
Vol 73 (a2) ◽  
pp. C119-C119
Author(s):  
Knut Müller-Caspary ◽  
M. Duchamp ◽  
F. F. Krause ◽  
A. Beche ◽  
F. Winkler ◽  
...  
Keyword(s):  
Electric Fields ◽  
Charge Densities

Deformation of an encapsulated bubble in steady and oscillatory electric fields

2018 ◽  
Vol 844 ◽  
pp. 567-596 ◽  
Author(s):  
Yunqiao Liu ◽  
Dongdong He ◽  
Xiaobo Gong ◽  
Huaxiong Huang
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Equilibrium Shape ◽  
Bubble Surface ◽  
Axisymmetric Deformation ◽  
Uniform Electric Field ◽  
Bending Rigidity ◽  
Shape Oscillation ◽  
Leaky Dielectric Model ◽  
Interfacial Charge

In this paper, we investigate the dynamics of an encapsulated bubble in steady and oscillatory electric fields theoretically, based on a leaky dielectric model. On the bubble surface, an applied electric field generates a Maxwell stress, in addition to hydrodynamic traction and membrane mechanical stress. Our model also includes the effect of interfacial charge due to the jump of the current and the stretching of the interface. We focus on the axisymmetric deformation of the encapsulated bubble induced by the electric field and carry out our analysis using Legendre polynomials. In our first example, the encapsulating membrane is modelled as a nearly incompressible interface with bending rigidity. Under a steady uniform electric field, the encapsulated bubble resumes an elongated equilibrium shape, dominated by the second- and fourth-order shape modes. The deformed shape agrees well with experimental observations reported in the literature. Our model reveals that the interfacial charge distribution is determined by the magnitude of the shape modes, as well as the permittivity and conductivity of the external and internal fluids. The effects of the electric field on the natural frequency of the oscillating bubble are also shown. For our second example, we considered a bubble encapsulated with a hyperelastic membrane with bending rigidity, subject to an oscillatory electric field. We show that the bubble can modulate its oscillating frequency and reach a stable shape oscillation at an appreciable amplitude.

Advanced Kinematic Scheme of Structural Calculation of Thin Multilayer Laminate With Essentially Diverse Layer’s Stiffness

2011 ◽  
Author(s):  
V. G. Gaynutdinov
Keyword(s):  
Mechanical Properties ◽  
Numerical Calculation ◽  
Numerical Algorithm ◽  
Composite Structure ◽  
Three Dimensional ◽  
Multilayer Structures ◽  
Main Task ◽  
Kinematic Scheme ◽  
Dimensional Approach ◽  
Structural Calculation

Composite structure consists of a system of layers bonded together. The layers can have different mechanical properties and thicknesses. The main task is to predict the behavior of a laminate as a system of layers with given properties. We suggest advanced kinematic scheme for structural calculation and heuristic numerical algorithm of prediction behavior of a multilayer structures with essentially diverse layer’s stiffness. Kinematic scheme can be compared in adequacy with three-dimensional approach of structural calculation of thin multilayer laminate, but is more economical in view of required resource for numerical calculation.

scholarly journals Equivalence of sessile droplet dynamics under periodic and steady electric fields

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Muhamed Ashfak Kainikkara ◽  
Dipin S. Pillai ◽  
Kirti Chandra Sahu
Keyword(s):  
Electric Field ◽  
Root Mean Square ◽  
Electric Fields ◽  
Mean Square ◽  
Sessile Droplet ◽  
Droplet Dynamics ◽  
Spherical Droplet ◽  
Microgravity Conditions ◽  
Freely Suspended ◽  
Interfacial Charge

AbstractThe electrohydrodynamics of a sessile droplet under the influence of periodic and steady electric fields in microgravity conditions is theoretically investigated using an inertial lubrication model. Previous studies have revealed that a freely suspended spherical droplet with unequal conductivity and permittivity ratios exhibits distinct dynamics under periodic and equivalent steady forcing in the root mean-square sense. However, it is unclear when (if at all) such distinct dynamics occur for periodic and equivalent steady forcing in the case of sessile droplets. The equivalence between periodic and steady forcing is shown to be governed by the interfacial charge buildup, which further depends on the competition between the charge relaxation and forcing timescales. A circulation-deformation map is introduced for the sessile droplet that acts as a guideline to achieve electric field-induced wetting or dewetting as the case may be. We also demonstrate that a droplet may be rendered either more or less wetting solely by tuning the forcing frequency.

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