Note on magneto-hydrodynamic gravitational stability of a double fluids interface

2008 ◽  
Vol 86 (3) ◽  
pp. 477-485
Author(s):  
Ahmed E Radwan ◽  
Mourad F Dimian
Keyword(s):  
Dispersion Relation ◽  
Present Model ◽  
The Self ◽  
Wave Number ◽  
Symmetric Mode ◽  
Fluid Interface ◽  
Unperturbed State ◽  
Gravitational Stability ◽  
The Stability ◽  
Range Force

The magneto–gravitational stability of double-fluid interface is discussed. The pressure in the unperturbed state is not constant because the self-gravitating force is a long-range force. The dispersion relation is derived and discussed. The self-gravitating model is unstable in the symmetric mode m = 0 (m is the transverse wave number), while it is stable in all other states. The effects of the densities, the liquid-fluid radii ratios, and the electromagnetic force on the stability of the present model are identified for all wavelengths.PACS Nos.: 47.35.Tv, 47.65.–d, 04.40.–b

STUDY ON ELECTROHYDRODYNAMIC CAPILLARY INSTABILITY OF VISCOELASTIC FLUIDS WITH RADIAL ELECTRIC FIELD

2014 ◽  
Vol 06 (04) ◽  
pp. 1450037
Author(s):  
MUKESH KUMAR AWASTHI
Keyword(s):  
Dispersion Relation ◽  
Electric Field ◽  
Radial Electric Field ◽  
Critical Value ◽  
Linear Analysis ◽  
Wave Number ◽  
Dual Effect ◽  
Capillary Instability ◽  
Viscous Potential Flow ◽  
The Stability

We study the linear analysis of electrohydrodynamic capillary instability of the interface between a viscous fluid and viscoelastic fluid of Maxwell type, when the phases are enclosed between two horizontal cylindrical surfaces coaxial with the interface, and when fluids are subjected to the radial electric field. Here, we use an irrotational theory known as viscous potential flow (VPF) theory in which viscosity enters through normal stress balance but shearing stresses are assumed to be zero. A quadratic dispersion relation that accounts for the growth of axisymmetric waves is obtained and stability criterion is given in terms of a critical value of wave number as well as electric field. It is observed that the radial electric field has dual effect on the stability of the system.

Three-Dimensional Viscous Potential Electrohydrodynamic Kelvin–Helmholtz Instability Through Vertical Cylindrical Porous Inclusions With Permeable Boundaries

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Galal M. Moatimid ◽  
Mohamed A. Hassan
Keyword(s):  
Dispersion Relation ◽  
Three Dimensional ◽  
Wave Number ◽  
Helmholtz Instability ◽  
Large Wave ◽  
Porous Layers ◽  
Azimuthal Wave ◽  
Azimuthal Wave Number ◽  
Streaming Velocity ◽  
The Stability

In this paper, the electrohydrodynamic three-dimensional Kelvin–Helmholtz instability of a cylindrical interface with heat and mass transfer between liquid and vapor phases is studied. The liquid and the vapor are saturated, two coaxial cylindrical porous layers, and the suction/injection velocities for the fluids at the permeable boundaries are also taken into account. The dispersion relation is derived and the stability analysis is discussed for various parameters. It is found that the streaming velocity has a destabilizing effect, while the axial electric field has a stabilizing one. The suction for both the liquid and the steam has a destabilizing effect in contrast with the injection at both boundaries. The flow through porous structure is more stable than the pure flow. The case of the axisymmetric (for zero value of the azimuthal wave number m) and asymmetric (for nonzero value of the azimuthal wave number m) disturbances at large wavelength (at the wave number k→0) are always stable. Meanwhile, it is the same dispersion relation for the plane geometry at large wave number. Finally, our results are corroborated by comparing them with the previous published results.

Influence of viscosity temperature dependence on the spectral characteristics of the thermoviscous liquids flow stability equation

2019 ◽  
Vol 14 (1) ◽  
pp. 52-58 ◽  
Author(s):  
A.D. Nizamova ◽  
V.N. Kireev ◽  
S.F. Urmancheev
Keyword(s):  
Reynolds Number ◽  
Spectral Characteristics ◽  
Wave Number ◽  
Critical Parameters ◽  
Fluid Viscosity ◽  
Flat Channel ◽  
Stability Equation ◽  
The Stability ◽  
Thermoviscous Fluid ◽  
Sommerfeld Equation

The flow of a viscous model fluid in a flat channel with a non-uniform temperature field is considered. The problem of the stability of a thermoviscous fluid is solved on the basis of the derived generalized Orr-Sommerfeld equation by the spectral decomposition method in Chebyshev polynomials. The effect of taking into account the linear and exponential dependences of the fluid viscosity on temperature on the spectral characteristics of the hydrodynamic stability equation for an incompressible fluid in a flat channel with given different wall temperatures is investigated. Analytically obtained profiles of the flow rate of a thermovisible fluid. The spectral pictures of the eigenvalues of the generalized Orr-Sommerfeld equation are constructed. It is shown that the structure of the spectra largely depends on the properties of the liquid, which are determined by the viscosity functional dependence index. It has been established that for small values of the thermoviscosity parameter the spectrum compares the spectrum for isothermal fluid flow, however, as it increases, the number of eigenvalues and their density increase, that is, there are more points at which the problem has a nontrivial solution. The stability of the flow of a thermoviscous fluid depends on the presence of an eigenvalue with a positive imaginary part among the entire set of eigenvalues found with fixed Reynolds number and wavenumber parameters. It is shown that with a fixed Reynolds number and a wave number with an increase in the thermoviscosity parameter, the flow becomes unstable. The spectral characteristics determine the structure of the eigenfunctions and the critical parameters of the flow of a thermally viscous fluid. The eigenfunctions constructed in the subsequent works show the behavior of transverse-velocity perturbations, their possible growth or decay over time.

scholarly journals Causality and stability conditions of a conformal charged fluid

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Farid Taghinavaz
Keyword(s):  
Chemical Potential ◽  
Second Law Of Thermodynamics ◽  
Dense Medium ◽  
Wave Number ◽  
Second Law ◽  
Stability Conditions ◽  
Charged Fluid ◽  
Large Wave ◽  
The Stability ◽  
Large Wave Number

Abstract In this paper, I study the conditions imposed on a normal charged fluid so that the causality and stability criteria hold for this fluid. I adopt the newly developed General Frame (GF) notion in the relativistic hydrodynamics framework which states that hydrodynamic frames have to be fixed after applying the stability and causality conditions. To do this, I take a charged conformal matter in the flat and 3 + 1 dimension to analyze better these conditions. The causality condition is applied by looking to the asymptotic velocity of sound hydro modes at the large wave number limit and stability conditions are imposed by looking to the imaginary parts of hydro modes as well as the Routh-Hurwitz criteria. By fixing some of the transports, the suitable spaces for other ones are derived. I observe that in a dense medium having a finite U(1) charge with chemical potential μ0, negative values for transports appear and the second law of thermodynamics has not ruled out the existence of such values. Sign of scalar transports are not limited by any constraints and just a combination of vector transports is limited by the second law of thermodynamic. Also numerically it is proved that the most favorable region for transports $$ {\tilde{\upgamma}}_{1,2}, $$ γ ˜ 1 , 2 , coefficients of the dissipative terms of the current, is of negative values.

Properties of strangelets at zero temperature in a new quark mass confinement model

2014 ◽  
Vol 23 (03) ◽  
pp. 1450013 ◽  
Author(s):  
Shiwu Chen ◽  
Qin Li ◽  
Jianfeng Xu ◽  
Li Gao ◽  
Chengjun Xia
Keyword(s):  
Quark Model ◽  
Quark Mass ◽  
Present Model ◽  
Baryon Number ◽  
Zero Temperature ◽  
Gluon Exchange ◽  
The Stability ◽  
Stable Radius ◽  
Confinement Model

We investigate the properties of strangelets at zero temperature with a new quark model in which the linear confinement and one-gluon-exchange (OGE) interactions are integrated as a whole. The charge, parameters dependence and the stability of strangelets are discussed. Our results showed that the OGE interaction lowers the energy of a strangelet, and consequently makes its stable radius smaller than that in the case of not including this interaction, and less than that of a nucleus with the same baryon number. Therefore, the strangelet in the present model has more chance to be absolutely stable.

Research on the Performances of Self-Oscillation Linear Actuator and its Compensation

2012 ◽  
Vol 433-440 ◽  
pp. 7375-7380
Author(s):  
Fan Lin ◽  
Li Qiao ◽  
Yu Wang ◽  
Hui Liu
Keyword(s):  
Nonlinear Model ◽  
Servo System ◽  
The Self ◽  
Linear Actuator ◽  
Phase Lag ◽  
Phase Lead ◽  
The Stability ◽  
Lag Compensation

Base on constitution of the self-oscillation linear actuator which is a servo system for a gun launched missile, a nonlinear model was built. Though the experiment, the model is correct. This paper studied the stability, the self-oscillation's frequency and gain on this kind of servo system. On comparing phase-lead compensation and phase-lag compensation, the later is more suitable for this system. After testing, the lag regulator is designed for the system.

AN INTERACTIONAL APPROACH TO ATTRIBUTIONAL DIMENSIONS IN DYSPHORIA

1990 ◽  
Vol 18 (2) ◽  
pp. 267-277 ◽  
Author(s):  
Janet E. Eschen ◽  
David S. Glenwick
Keyword(s):  
Attributional Style ◽  
The Self ◽  
Regression Analyses ◽  
Self Blame ◽  
Attributional Style Questionnaire ◽  
Standard Manner ◽  
Stability Dimension ◽  
The Stability ◽  
The Relationship

To investigate the possible contributions to dysphoria of interactions among attributional dimensions, 105 freshmen and sophomores were administered the Attributional Style Questionnaire and the Beck Depression Inventory. Analyses examined the relationship to dysphoria of (a) the traditional composite score; (b) multiple regression analyses including interactions among the various dimensions; and (c) indices of behavioral self-blame, characterological self-blame, and external blame. The results provided modest support for the specific hypothesized interactional model and, to a large extent, appeared to support the validity of the standard manner in which dysphoric attributional style is viewed. Refinements of the traditional model are suggested, involving the self-blame construct, the possible role of the stability dimension, and the relationship between controllability and positive event attributions.

scholarly journals On Minimum-B Stabilization of Electrostatic Drift Instabilities

1966 ◽  
Vol 21 (11) ◽  
pp. 1953-1959 ◽  
Author(s):  
R. Saison ◽  
H. K. Wimmel
Keyword(s):  
Dispersion Relation ◽  
Particle Distribution ◽  
Inhomogeneous Plasma ◽  
Distribution Functions ◽  
Loss Cone ◽  
First Order ◽  
Stabilization Theorem ◽  
The Stability ◽  
Necessary And Sufficient ◽  
Limiting Case

A check is made of a stabilization theorem of ROSENBLUTH and KRALL (Phys. Fluids 8, 1004 [1965]) according to which an inhomogeneous plasma in a minimum-B field (β ≪ 1) should be stable with respect to electrostatic drift instabilities when the particle distribution functions satisfy a condition given by TAYLOR, i. e. when f0 = f(W, μ) and ∂f/∂W < 0 Although the dispersion relation of ROSENBLUTH and KRALL is confirmed to first order in the gyroradii and in ε ≡ d ln B/dx z the stabilization theorem is refuted, as also is the validity of the stability criterion used by ROSEN-BLUTH and KRALL, ⟨j·E⟩ ≧ 0 for all real ω. In the case ωpi ≫ | Ωi | equilibria are given which satisfy the condition of TAYLOR and are nevertheless unstable. For instability it is necessary to have a non-monotonic ν ⊥ distribution; the instabilities involved are thus loss-cone unstable drift waves. In the spatially homogeneous limiting case the instability persists as a pure loss cone instability with Re[ω] =0. A necessary and sufficient condition for stability is D (ω =∞, k,…) ≦ k2 for all k, the dispersion relation being written in the form D (ω, k, K,...) = k2+K2. In the case ωpi ≪ | Ωi | adherence to the condition given by TAYLOR guarantees stability.

scholarly journals Two-Dimensional Convection Induced by Gravity and Centrifugal Forces in a Rotating Porous Layer Far Away from the Axis of Rotation

1998 ◽  
Vol 4 (2) ◽  
pp. 73-90 ◽  
Author(s):  
Peter Vadasz ◽  
Saneshan Govender
Keyword(s):  
Rayleigh Number ◽  
Porous Layer ◽  
Temperature Fields ◽  
Wave Number ◽  
Marginal Stability ◽  
Two Dimensional ◽  
Wide Range ◽  
Gravity Driven ◽  
Gravity Driven Flow ◽  
The Stability

The stability and onset of two-dimensional convection in a rotating fluid saturated porous layer subject to gravity and centrifugal body forces is investigated analytically. The problem corresponding to a layer placed far away from the centre of rotation was identified as a distinct case and therefore justifying special attention. The stability of a basic gravity driven convection is analysed. The marginal stability criterion is established in terms of a critical centrifugal Rayleigh number and a critical wave number for different values of the gravity related Rayleigh number. For any given value of the gravity related Rayleigh number there is a transitional value of the wave number, beyond which the basic gravity driven flow is stable. The results provide the stability map for a wide range of values of the gravity related Rayleigh number, as well as the corresponding flow and temperature fields.

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