scholarly journals Influence of Electric Fields and Boundary Conditions on the Flow Properties of Nematic-Filled Cells and Capillaries

Rheology ◽  
10.5772/34887 ◽  
2012 ◽  
Author(s):  
Carlos I. ◽  
Adalberto Corella-Madueo ◽  
J. Adrin
Keyword(s):  
Boundary Conditions ◽  
Electric Fields ◽  
Flow Properties

scholarly journals Validation of the stream function method used for reconstruction of experimental ionospheric convection patterns

2000 ◽  
Vol 18 (4) ◽  
pp. 454-460
Author(s):  
P.L. Israelevich ◽  
V. O. Papitashvili ◽  
A. I. Ershkovich
Keyword(s):  
Boundary Value Problem ◽  
Boundary Conditions ◽  
Stream Function ◽  
Electric Fields ◽  
Electric Potential ◽  
Potential Distribution ◽  
Function Method ◽  
Polar Cap ◽  
Ionospheric Convection ◽  
Convection Patterns

Abstract. In this study we test a stream function method suggested by Israelevich and Ershkovich for instantaneous reconstruction of global, high-latitude ionospheric convection patterns from a limited set of experimental observations, namely, from the electric field or ion drift velocity vector measurements taken along two polar satellite orbits only. These two satellite passes subdivide the polar cap into several adjacent areas. Measured electric fields or ion drifts can be considered as boundary conditions (together with the zero electric potential condition at the low-latitude boundary) for those areas, and the entire ionospheric convection pattern can be reconstructed as a solution of the boundary value problem for the stream function without any preliminary information on ionospheric conductivities. In order to validate the stream function method, we utilized the IZMIRAN electrodynamic model (IZMEM) recently calibrated by the DMSP ionospheric electrostatic potential observations. For the sake of simplicity, we took the modeled electric fields along the noon-midnight and dawn-dusk meridians as the boundary conditions. Then, the solution(s) of the boundary value problem (i.e., a reconstructed potential distribution over the entire polar region) is compared with the original IZMEM/DMSP electric potential distribution(s), as well as with the various cross cuts of the polar cap. It is found that reconstructed convection patterns are in good agreement with the original modelled patterns in both the northern and southern polar caps. The analysis is carried out for the winter and summer conditions, as well as for a number of configurations of the interplanetary magnetic field.Key words: Ionosphere (electric fields and currents; plasma convection; modelling and forecasting)

CIR versus CME drivers of the ring current during intense magnetic storms

2010 ◽  
Vol 466 (2123) ◽  
pp. 3305-3328 ◽  
Author(s):  
Michael W. Liemohn ◽  
Matt Jazowski ◽  
Janet U. Kozyra ◽  
Natalia Ganushkina ◽  
Michelle F. Thomsen ◽  
...  
Keyword(s):  
Solar Wind ◽  
Boundary Conditions ◽  
Electric Fields ◽  
Data Model ◽  
Goodness Of Fit ◽  
Plasma Boundary ◽  
Magnetic Storms ◽  
Hot Electron ◽  
Interplanetary Coronal Mass Ejections ◽  
Interaction Regions

Ninety intense magnetic storms (minimum Dst value of less than −100 nT) from solar cycle 23 (1996–2005) were simulated using the hot electron and ion drift integrator (HEIDI) model. All 90 storm intervals were run with several electric fields and nightside plasma boundary conditions (five run sets). Storms were classified according to their solar wind driver, including corotating interaction regions (CIRs) and interplanetary coronal mass ejections (ICMEs). Data-model comparisons were made against the observed Dst index (specifically, Dst*) and dayside hot-ion measurements from geosynchronous orbiting spacecraft. It is found that the data-model goodness-of-fit values are different for CIR-driven storms relative to ICME-driven storms. The results are also different for the same storm category for different boundary conditions. None of the CIR-driven events was overpredicted by HEIDI, while the dayside comparisons were comparable for the different drivers. The results imply that the outer magnetosphere is responding differently to the two kinds of solar wind drivers, even though the resulting storm size might be similar. That is, for ICME-driven events, magnetospheric currents inside of geosynchronous orbit dominate the Dst perturbation, while for CIR-driven events, currents outside of this boundary have a systematically larger contribution.

NONLINEAR STRAIN GRADIENT THEORY BASED VIBRATION AND INSTABILITY OF BORON NITRIDE MICRO-TUBES CONVEYING FERROFLUID

2014 ◽  
Vol 06 (05) ◽  
pp. 1450060 ◽  
Author(s):  
ALI GHORBANPOUR ARANI ◽  
ABDOLREZA JALILVAND ◽  
REZA KOLAHCHI
Keyword(s):  
Magnetic Field ◽  
Boron Nitride ◽  
Boundary Conditions ◽  
Electric Fields ◽  
Strain Gradient ◽  
Differential Quadrature Method ◽  
Fluid Velocity ◽  
Strain Gradient Theory ◽  
Gradient Theory ◽  
Nonlinear Frequency

Nonlinear vibration and instability of a boron nitride micro-tube (BNMT) conveying ferrofluid under the combined magnetic and electric fields are investigated. Based on Euler–Bernoulli beam (EBB), piezoelasticity strain gradient theory and Hamilton's principle, high order equations of motion are derived for three boundary conditions namely as clamped–clamped (C–C), simply–simply (S–S) and clamped–simply (C–S). The differential quadrature method (DQM) is applied to discretize the motion equations in order to obtain the nonlinear frequency and critical fluid velocity using a direct iterative method. A detailed parametric study is conducted to elucidate the influences of the various boundary conditions, size diameter and magnetic field on vibrational characteristic of BNMT. Numerical results indicate that the effect of magnetic field appears in higher speed of ferrofluid and increases the critical velocity or enlarges the stability region. The results are in good agreement with the previous researches. The results of this study can be used to manufacture smart micro/nano electromechanical systems in advanced biomechanics applications with magnetic and electric fields as parametric controllers.

Granular Flow Lubrication: Continuum Modeling of Shear Behavior

2004 ◽  
Vol 126 (3) ◽  
pp. 499-510 ◽  
Author(s):  
C. Fred Higgs, ◽  
John Tichy
Keyword(s):  
Boundary Conditions ◽  
Energy Transport ◽  
Granular Flows ◽  
Solid Particles ◽  
Numerical Code ◽  
Flow Properties ◽  
Local Flow ◽  
Shear Cell ◽  
Coupled Boundary Conditions ◽  
Lubricating Mechanism

Because at extreme temperatures, conventional liquid lubrication breaks down, researchers have proposed using flows of solid particles as a lubricating mechanism. The particles may be powders, which tend to coalesce and slide over one another in sustained contact, or granules, which collide with one another in fluctuating motion. Distinction between these two regimes is elucidated. The behavior of various granular flows is studied using a granular kinetic lubrication (GKL) model. Our GKL model is a continuum approach that applies proper rheological constitutive equations for stress, conduction and dissipation to thin shearing flows of granular particles, as well as the most rigorous boundary conditions for momentum and energy transport. A robust numerical code, utilizing Newton’s finite differencing method, is developed to apply GKL theory to the problem of simple shearing flow. The code solves two second-order, coupled nonlinear ordinary differential equations with coupled boundary conditions of the first-order. As a result, new parametric curves for the local flow properties of the large-particle granular flows are constructed. Results from the GKL model agree qualitatively with past experiments using glass granules in an annular shear cell.

scholarly journals Storm-time ring current: model-dependent results

2012 ◽  
Vol 30 (1) ◽  
pp. 177-202 ◽  
Author(s):  
N. Yu. Ganushkina ◽  
M. W. Liemohn ◽  
T. I. Pulkkinen
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Boundary Conditions ◽  
Electric Fields ◽  
Ring Current ◽  
Current Model ◽  
Current Data ◽  
Storm Events ◽  
Boundary Location ◽  
Field Lines

Abstract. The main point of the paper is to investigate how much the modeled ring current depends on the representations of magnetic and electric fields and boundary conditions used in simulations. Two storm events, one moderate (SymH minimum of −120 nT) on 6–7 November 1997 and one intense (SymH minimum of −230 nT) on 21–22 October 1999, are modeled. A rather simple ring current model is employed, namely, the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM), in order to make the results most evident. Four different magnetic field and two electric field representations and four boundary conditions are used. We find that different combinations of the magnetic and electric field configurations and boundary conditions result in very different modeled ring current, and, therefore, the physical conclusions based on simulation results can differ significantly. A time-dependent boundary outside of 6.6 RE gives a possibility to take into account the particles in the transition region (between dipole and stretched field lines) forming partial ring current and near-Earth tail current in that region. Calculating the model SymH* by Biot-Savart's law instead of the widely used Dessler-Parker-Sckopke (DPS) relation gives larger and more realistic values, since the currents are calculated in the regions with nondipolar magnetic field. Therefore, the boundary location and the method of SymH* calculation are of key importance for ring current data-model comparisons to be correctly interpreted.

Electrorheology

MRS Bulletin ◽  
1991 ◽  
Vol 16 (8) ◽  
pp. 38-43 ◽  
Author(s):  
Therese C. Jordan ◽  
Montgomery T. Shaw
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
High Speed ◽  
Flow Properties ◽  
Electric Field Effects ◽  
Properties Of Materials ◽  
Strong Electric Fields ◽  
Silica Suspensions ◽  
Type Of Behavior ◽  
Damping Systems

The influence of electric fields on the deformation and flow properties of materials has been a subject of interest for many years. Recently, there has been renewed interest in a particular branch of these electric field effects—the electrorheological (ER) effect. The ER effect is also known as the Winslow effect after its founder Willis Winslow. Winslow observed that applying strong electric fields to nonaqueous silica suspensions activated with a small amount of water caused rapid solidification of the originally fluid material. This type of behavior was seen as instrumental in the development of high-speed valves, reactive damping systems, and a host of other applications.

Bending Characteristics of Plate-Type Piezoelectric Composite Actuators According to Applied Electric Fields and Drive Frequencies

2006 ◽  
Vol 326-328 ◽  
pp. 1701-1704 ◽  
Author(s):  
Sung Choong Woo ◽  
Nam Seo Goo
Keyword(s):  
Boundary Condition ◽  
Free Boundary ◽  
Electric Field ◽  
Boundary Conditions ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Piezoelectric Composite ◽  
Simply Supported ◽  
Drive Frequency ◽  
Plate Type

A performance evaluation of plate-type piezoelectric composite actuators (PCA) having different lay-up sequences was experimentally carried out at simply supported and fixed-free boundary conditions. The actuating displacement of the manufactured PCAs was measured using a non-contact laser displacement measurement system. It was shown that the actuating displacement with increasing applied electric field at a drive frequency of 1 Hz increased nonlinearly at the simply supported boundary condition whereas it almost linearly increased at the fixed-free boundary condition. In contrast, the actuating displacement of the PCAs depended on the applied electric fields in a drive frequency range from 1 Hz to 10 Hz. However, the displacement behavior of PCAs varied significantly at a higher range of drive frequency, i.e., beyond 15 Hz, due to the occurrence of resonance. On the basis of these experimental results, the bending characteristics of PCAs in relation to applied electric field, drive frequency, and boundary conditions were elucidated.

Nonlinear instability of two dielectric viscoelastic fluids

2004 ◽  
Vol 82 (12) ◽  
pp. 1109-1133 ◽  
Author(s):  
Galal M Moatimid
Keyword(s):  
Boundary Conditions ◽  
Electric Fields ◽  
Multiple Scales ◽  
Landau Equation ◽  
Equations Of Motion ◽  
Nonlinear Boundary Conditions ◽  
Interfacial Wave ◽  
Surface Evolution ◽  
Stability Diagrams ◽  
Viscoelastic Effects

A weakly nonlinear interfacial wave propagating between two dielectric fluids and influenced by an oblique electric field is studied. The analysis considers the surface tension and viscoelastic effects. Due to the presence of streaming and viscoelasticity, a mathematical simplification is considered. The viscoelastic contribution is demonstrated through the boundary conditions. Therefore, the equations of motion are solved in the absence of the viscoelastic effects. The solutions of the linearized equations of motion under the nonlinear boundary conditions lead to a nonlinear characteristic equation governing the surface evolution. This equation is accomplished by utilizing cubic nonlinearity. Taylor theory is adopted to expand the characteristic nonlinear equation in the light of the multiple-scales technique. The perturbation analysis produces two levels of the solvability conditions, which are used to construct the Ginzburg–Landau equation. Stability criteria are discussed both theoretically and computationally in which stability diagrams are obtained. Under appropriate data choices, we can recover some reported works as limiting cases. The effects of the orientation of the electric fields on the stability configuration in linear as well as nonlinear approaches are discussed. PACS Nos.: 47.65.+a, 47.20.–k, 47.50.+d

Electric–elastic analysis of multilayered two-dimensional decagonal quasicrystal circular plates with simply supported or clamped boundary conditions

2021 ◽  
pp. 108128652098161
Author(s):  
Yunzhi Huang ◽  
Min Zhao ◽  
Miaolin Feng
Keyword(s):  
Boundary Conditions ◽  
Electric Fields ◽  
Radial Coordinate ◽  
Elastic Analysis ◽  
Two Dimensional ◽  
Circular Plates ◽  
State Equations ◽  
Element Analysis ◽  
Decagonal Quasicrystal ◽  
Simply Supported

A three-dimensional (3D) electric–elastic analysis of multilayered two-dimensional decagonal quasicrystal (QC) circular plates with simply supported or clamped boundary conditions is presented through a state vector approach. Both perfect and imperfect bonds between the layers are considered by adjusting the parameter sets in the model. Governing equations for the plates subjected to electric or elastic load on the bottom surfaces are derived using the state equations and the propagator matrix method. We explicitly obtain the analytical solution by writing the physical variables as Bessel series expansions and polynomial functions with respect to the radial coordinate. The solution is validated by comparing the numerical results with the 3D finite element analysis. The basic physical quantities of the plates in the phonon, phason, and electric fields are computed in the numerical examples. Result shows that the QC layers as coatings decrease the deflection in the phonon and phason fields of plates. The phonon–phason coupling elastic modulus and piezoelectric constant produce positive and negative effects on the magnitudes of stresses. Besides, compliance coefficients of the weak interface in the phonon field contribute more to the variations than those in the phason field.

scholarly journals Computational Analysis of Heat Transfer Intensification of Fractional Viscoelastic Hybrid Nanofluids

2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Mumtaz Khan ◽  
Amer Rasheed
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Electric Fields ◽  
Computational Analysis ◽  
Numerical Solutions ◽  
Numerical Technique ◽  
Fluid Motion ◽  
Convection Heat Transfer ◽  
Point Of View ◽  
Hybrid Nanofluid

In the current article, we have performed computational analysis on convection heat transfer of a hybrid nanofluid in occurrences where porous media and the effect of magnetic force are involved. In order to assess the time-fractional derivatives, Caputo’s notion is utilized while the Darcy–Forchheimer model is applied due to the involvement of the porous medium. Moreover, the boundary conditions are assumed to be nonuniform through the equilibrium between the surface tension and shear stress over a semi-infinite permeable flat surface. Keeping in view the complexity of the fractional derivative model and nonuniform boundary conditions, the problem in question is a complicated one. Accordingly, the coupled momentum and energy equation is linearized and the finite difference scheme is then applied and implemented in MATLAB Code R2020b. Furthermore, we have also offered a comprehensive analysis regarding error and convergence of the proposed numerical method. The newly introduced numerical technique to determine the numerical solutions and some unique and interesting deductions are established. From the computational results, one can conclude that the fluid motion in both hybrid and single nanofluids slows down due to magnetic field, porosity, and inertia coefficient as the magnetic and electric fields are synchronized due to the formation of the Lorentz force and viscous interference. We believe that our proposed numerical technique regarding employment of the fractional model for heat transfer application to the hybrid nanofluid over a semi-infinite nonuniform permeable surface along with variable heat flux is not found in the literature so far. Furthermore, the obtained results will be a valuable addition to fractional calculus from an engineering point of view.

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