scholarly journals Dynamics of liquid films on vertical fibres in a radial electric field

2014 ◽  
Vol 752 ◽  
pp. 66-89 ◽  
Author(s):  
Zijing Ding ◽  
Jinlong Xie ◽  
Teck Neng Wong ◽  
Rong Liu
Keyword(s):  
Electric Field ◽  
Wave Speed ◽  
Nonlinear Evolution ◽  
Radial Electric Field ◽  
Liquid Films ◽  
Asymptotic Model ◽  
Nonlinear Behaviour ◽  
Wave Instability ◽  
Long Wave ◽  
Evolution Study

AbstractThe long-wave behaviour of perfectly conducting liquid films flowing down a vertical fibre in a radial electric field was investigated by an asymptotic model. The validity of the asymptotic model was verified by the fully linearized problem, which showed that results were in good agreement in the long-wave region. The linear stability analysis indicated that, when the ratio (the radius of the outer cylindrical electrode over the radius of the liquid film) $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}\beta <e$, the electric field enhanced the long-wave instability; when $\beta >e$, the electric field impeded the long-wave instability; when $\beta =e$, the electric field did not affect the long-wave instability. The nonlinear evolution study of the asymptotic model compared well with the linear theory when $\beta <e$. However, when $\beta =e$, the nonlinear evolution study showed that the electric field enhanced the instability which may cause the interface to become singular. When $\beta >e$, the nonlinear evolution studies showed that the influence of the electric field on the nonlinear behaviour of the interface was complex. The electric field either enhanced or impeded the interfacial instability. In addition, an interesting phenomenon was observed by the nonlinear evolution study that the electric field may cause an oscillation in the amplitude of permanent waves when $\beta \ge e$. Further study on steady travelling waves was conducted to reveal the influence of electric field on the wave speed. Results showed that the electric field either increased or decreased the wave speed as well as the wave amplitude and flow rate. In some situations, the wave speed may increase/decrease while its amplitude decreased/increased as the strength of the external electric field increased.

The mechanism for the long-wave instability in thin liquid films

1990 ◽  
Vol 217 ◽  
pp. 469-485 ◽  
Author(s):  
Marc K. Smith
Keyword(s):  
Physical Mechanism ◽  
Thin Liquid Film ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
The Other ◽  
Wave Instability ◽  
Inclined Plane ◽  
Long Wave ◽  
The Many ◽  
Large Groups

A physical mechanism for the long-wave instability of thin liquid films is presented. We show that the many diverse systems that exhibit this instability can be classified into two large groups. Each group is studied using the model of a thin liquid film with a deformable top surface flowing down a rigid inclined plane. In the first group, the top surface has an imposed stress, while in the other, an imposed velocity. The proposed mechanism shows how the details of the energy transfer from the basic state to the disturbance are handled differently in each of these cases, and how a common growth mechanism produces the unstable motion of the disturbance.

scholarly journals Waves and vibrations in a finitely deformed electroelastic circular cylindrical tube

2020 ◽  
Vol 476 (2233) ◽  
pp. 20190701 ◽  
Author(s):  
Luis Dorfmann ◽  
Ray W. Ogden
Keyword(s):  
Electric Field ◽  
Wave Speed ◽  
Cylindrical Tube ◽  
Radial Electric Field ◽  
Potential Difference ◽  
Axisymmetric Vibration ◽  
End Conditions ◽  
Circular Cylindrical Tube ◽  
Special Case ◽  
Tube Geometry

In two recent papers, conditions for which axisymmetric incremental bifurcation could arise for a circular cylindrical tube subject to axial extension and radial inflation in the presence of an axial load, internal pressure and a radial electric field were examined, the latter being effected by a potential difference between compliant electrodes on the inner and outer radial surfaces of the tube. The present paper takes this work further by considering the incremental deformations to be time-dependent. In particular, both the axisymmetric vibration of a tube of finite length with appropriate end conditions and the propagation of axisymmetric waves in a tube are investigated. General equations and boundary conditions governing the axisymmetric incremental motions are obtained and then, for purposes of numerical evaluation, specialized for a Gent electroelastic model. The resulting system of equations is solved numerically and the results highlight the dependence of the frequency of vibration and wave speed on the tube geometry, applied deformation and electrostatic potential. In particular, the bifurcation results obtained previously are recovered as a special case when the frequency vanishes. Specification of an incremental potential difference in the present work ensures that there is no incremental electric field exterior to the tube. Results are also illustrated for a neo-Hookean electroelastic model and compared with those previously obtained for the case in which no incremental potential difference (or charge) is specified and an external field is required.

scholarly journals Investigation of turbulence rotation and radial electric field in the island divertor and plasma edge at W7-X

2019 ◽  
Vol 61 (5) ◽  
pp. 054003 ◽  
Author(s):  
A Krämer-Flecken ◽  
X Han ◽  
T Windisch ◽  
J Cosfeld ◽  
P Drews ◽  
...  
Keyword(s):  
Electric Field ◽  
Radial Electric Field ◽  
Plasma Edge

Self-Assembly of Monolayers of Submicron Sized Particles on Thin Liquid Films

2013 ◽  
Author(s):  
Shriram Pillapakkam ◽  
N. A. Musunuri ◽  
P. Singh
Keyword(s):  
Electric Field ◽  
Self Assembly ◽  
Uv Light ◽  
Capillary Forces ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Liquid Interfaces ◽  
Uv Curable ◽  
Particle Monolayer ◽  
Uv Curable Resin

In this paper, we present a technique for freezing monolayers of micron and sub-micron sized particles onto the surface of a flexible thin film after the self-assembly of a particle monolayer on fluid-liquid interfaces has been improved by the process we have developed where an electric field is applied in the direction normal to the interface. Particles smaller than about 10 microns do not self-assemble under the action of lateral capillary forces alone since capillary forces amongst them are small compared to Brownian forces. We have overcome this problem by applying an electric field in the direction normal to the interface which gives rise to dipoledipole and capillary forces which cause the particles to arrange in a triangular pattern. The technique involves assembling the monolayer on the interface between a UV-curable resin and another liquid by applying an electric field, and then curing the resin by applying UV light. The monolayer becomes embedded on the surface of the solidified resin film.

Gas-ionizing shocks in a magnetic field

1967 ◽  
Vol 1 (1) ◽  
pp. 37-54 ◽  
Author(s):  
M. D. Cowley
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Wave Speed ◽  
Normal Velocity ◽  
Electrically Conducting ◽  
Shock Stability ◽  
The Face ◽  
Arbitrary Velocity ◽  
Flow Plane ◽  
The Magnetic Field

Ionizing shocks for plane flows with the magnetic field lying in the flow plane are considered. The gas is assumed to be electrically conducting downstream, but non-conducting upstream. Shocks whose downstream state has a normal velocity component less than the slow magneto-acoustic-wave speed and whose upstream state is supersonic are found to be non-evolutionary in the face of plane magneto-acoustic disturbances, unless the upstream electric field in a frame of reference where the gas is at rest is arbitrary. Velocity conditions are also determined for shock stability with the electric field not arbitrary.Shock structures are found for the case of large ohmic diffusion, the initial temperature rise and ionization of the gas being caused by a thin transition having the properties of an ordinary gasdynamic shock. For the case where shocks are evolutionary when the upstream electric field is arbitrary, the shock structure requirements only restrict the electric field by limiting the range of possible values. When shocks are evolutionary with the electric field not arbitrary, they can only have a structure for a particular value of the electric field. Limits to the current carried by ionizing shocks and the effects of precursor ionization are discussed qualitatively.

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