scholarly journals Inviscid Faraday waves in a brimful circular cylinder

2013 ◽  
Vol 724 ◽  
pp. 671-694 ◽  
Author(s):  
R. Kidambi
Keyword(s):  
Circular Cylinder ◽  
Contact Line ◽  
Stability Diagram ◽  
Bond Number ◽  
Faraday Waves ◽  
Almost Periodic ◽  
Contact Lines ◽  
Stability Diagrams ◽  
The Stability ◽  
Subharmonic Resonances

AbstractWe study inviscid Faraday waves in a brimful circular cylinder with pinned contact line. The pinning leads to a coupling of the Bessel modes and leads to an infinite system of coupled Mathieu equations. For large Bond numbers, even though the stability diagrams and the subharmonic and harmonic resonances for the free and pinned contact lines are similar, the free surface shapes can be quite different. With decreasing Bond number, not only are the harmonic and subharmonic resonances very different from the free contact line case but also interesting changes in the stability diagram occur with the appearance of combination resonance tongues. Points on these tongue boundaries correspond to almost-periodic states. These do not seem to have been reported in the literature.

Dynamic Stability Characteristics of Axially Accelerated Beams

2006 ◽  
Vol 321-323 ◽  
pp. 1654-1658 ◽  
Author(s):  
Hong Hee Yoo ◽  
Sung Jin Eun
Keyword(s):  
Dynamic Stability ◽  
Natural Frequencies ◽  
Equations Of Motion ◽  
Stability Diagram ◽  
Accelerated Motion ◽  
Stability Diagrams ◽  
Divergence Type ◽  
The Stability ◽  
Direct Numerical Integration ◽  
Free Beam

Dynamic stability of axially accelerated beams is investigated in this paper. The equations of motion of a fixed-free beam undergoing axially accelerated motion are derived. Unstable regions due to the acceleration are obtained by using the Floquet’s theory. Stability diagrams are presented to illustrate the influence of the acceleration characteristics. Large unstable regions of flutter type instability exist around the first, twice the first, and twice the second bending natural frequencies. Divergence type instability also occurs when the acceleration exceeds a certain value. The validity of the stability diagram is confirmed by direct numerical integration of the equations of motion.

Contact line instability in spontaneous spreading of a drop on a solid surface

2001 ◽  
Vol 428 ◽  
pp. 171-183 ◽  
Author(s):  
P. NEOGI
Keyword(s):  
Solid Surface ◽  
Contact Line ◽  
Dynamic Contact ◽  
Contact Lines ◽  
Large Curvature ◽  
Line Region ◽  
The Stability ◽  
Dynamic Contact Line ◽  
Wetting Kinetics ◽  
Kinetics Of

The wetting kinetics of a drop on a solid surface is measured by observing the movement of the contact line, which is often seen to be unstable, showing a scalloped profile. Many factors have been cited, which, although they can cause instability, can also be eliminated from the experiments, but still the instabilities appear. The basic shape of a spreading drop has a large curvature localized in the vicinity of the contact line as determined by microscopy. It is shown here using linear stability analysis that this curvature can destabilize the contact line region. When the drop profile is disturbed from a basic thickness of h to h + h′, there are two contributions from h′ in the form of added Laplace pressure. One of these is commonly accounted for in the stability analyses. The other is not, and occurs only if the basic shape has a curvature, and the drop has a large curvature near the apparent dynamic contact line, but only for a wetting liquid. This is why instability is not reported in the case of spreading of drops of non-wetting liquids. It also explains why instability gives rise to the changed spreading kinetics of drops that are sometimes reported in the literature, and suggests that as larger curvatures are expected in forced spreading those cases are probably accompanied quite frequently by unstable contact lines.

Capillary surfaces: stability from families of equilibria with application to the liquid bridge

1995 ◽  
Vol 449 (1937) ◽  
pp. 411-439 ◽  
Keyword(s):  
Equilibrium State ◽  
Liquid Bridge ◽  
Equilibrium Shape ◽  
Bond Number ◽  
Contact Lines ◽  
Capillary Surfaces ◽  
Diagram Method ◽  
Theory Application ◽  
The Stability ◽  
Bridge Length

A method for determining the stability of general static capillary surfaces is illustrated by application to the liquid bridge. Axisymmetric bridges with fixed contact lines under gravity are parametrized by three quantities: bridge length L , bridge volume V , and Bond number B . The method delivers: (i) stability envelopes in the { L, V, B } parameter space for constant-pressure and constant-volume disturbances (generating new and recovering classical results), (ii) the number of unstable modes for any equilibrium (state of instability) once the stability of one equilibrium state is known (e. g. that of the sphere) based on (iii) a demonstration that all known families of equilibria are connected. The method uses ‘preferred’ bifurcation diagrams, a plot of volume V against pressure p . The state of instability of an equilibrium shape relative to its neighbours is immediate from this plot. In addition, an invariant wavenumber classification is introduced and used to label the numerous families of liquid bridge equilibria. The preferred diagram method, which is based on properties of the Jacobi equation, gives stronger results than classical bifurcation theory. Application to other capillary surfaces, including drops and non-axisymmetric shapes, is discussed.

Effect of Process Damping on Longitudinal Vibrations in Drillstrings

1994 ◽  
Vol 116 (2) ◽  
pp. 129-135 ◽  
Author(s):  
M. A. Elsayed ◽  
R. L. Wells ◽  
D. W. Dareing ◽  
K. Nagirimadugu
Keyword(s):  
Shock Absorber ◽  
Stability Diagram ◽  
Field Observations ◽  
Longitudinal Vibrations ◽  
Process Damping ◽  
Stability Diagrams ◽  
Drag Bits ◽  
The Stability ◽  
Cut Surface ◽  
Cutting Speeds

This paper shows the effect of process damping—caused by the interference between the cutter and the previously cut surface—on the stability of drillstrings. The method of including process damping in the calculation of the stability diagram is outlined. Previously published stability diagrams of drillstrings equipped with drag bits showed decreased stability at low cutting speeds, and that the addition of a shock absorber decreased the size of stability pockets. In this paper, we show that the introduction of process damping confirms field observations of increased stability at low speeds. We also show that a properly designed shock absorber produces large stability pockets where drilling is most effective.

scholarly journals The Effect of Non-Symmetric FRF on Machining: A Case Study

2015 ◽  
Author(s):  
David Hajdu ◽  
Tamas Insperger ◽  
Gabor Stepan
Keyword(s):  
Frequency Response ◽  
Degrees Of Freedom ◽  
Stability Diagram ◽  
Domain Model ◽  
Practical Applications ◽  
Stability Diagrams ◽  
Machining Center ◽  
Milling Operations ◽  
The Stability ◽  
Machining Operations

Stability prediction of machining operations is often not reliable due to the inaccurate mechanical modeling. A major source of this inaccuracy is the uncertainties in the dynamic parameters of the machining center at different spindle speeds. The so-called tip-to-tip measurement is the fastest and most convenient method to determine the frequency response of the machine. This concept consists of the measurement of the tool tip’s frequency response function (FRF) usually in two perpendicular directions including cross terms. Although the cross FRFs are often neglected in practical applications, they may affect the system’s dynamics. In this paper, the stability diagrams are analyzed for milling operations in case of diagonal, symmetric and non-symmetric FRF matrices. First a time-domain model is derived by fitting a multiple-degrees-of-freedom model to the FRF matrix, then the semi-discretization method is used to determine stability diagrams. The results show that the omission of the non-symmetry of the FRF matrix may lead to inaccurate stability diagram.

Test of the stability of a three-phase contact line with negative line tension

1999 ◽  
Vol 96 (9) ◽  
pp. 1335-1339 ◽  
Author(s):  
ALAN E. VAN GIESSEN, DIRK JAN BUKMAN, B.
Keyword(s):  
Contact Line ◽  
Line Tension ◽  
Phase Contact ◽  
Three Phase ◽  
The Stability

Global Stability Analysis of the Wake behind a Circular Cylinder Based on the POD-Chiba Method

2011 ◽  
Vol 137 ◽  
pp. 72-76
Author(s):  
Wei Zhang ◽  
Xian Wen ◽  
Yan Qun Jiang
Keyword(s):  
Stability Analysis ◽  
Circular Cylinder ◽  
Global Stability ◽  
Dimensional Model ◽  
Global Stability Analysis ◽  
The Stability ◽  
Low Dimensional ◽  
Proper Orthogonal ◽  
Calculated Amount ◽  
Good Agreement

A proper orthogonal decomposition (POD) method is applied to study the global stability analysis for flow past a stationary circular cylinder. The flow database at Re=100 is obtained by CFD software, i.e. FLUENT, with which POD bases are constructed by a snapshot method. Based on the POD bases, a low-dimensional model is established for solving the two-dimensional incompressible NS equations. The stability of the flow solution is evaluated by a POD-Chiba method in the way of the eigensystem analysis for the velocity disturbance. The linear stability analysis shows that the first Hopf bifurcation takes place at Re=46.9, which is in good agreement with available results by other high-order accurate stability analysis methods. However, the calculated amount of POD is little, which shows the availability and advantage of the POD method.

CHARGE STABILITY AND CONDUCTANCE ANALYSIS OF ANTHRACENE-BASED SINGLE ELECTRON TRANSISTOR

2013 ◽  
Vol 12 (06) ◽  
pp. 1350045 ◽  
Author(s):  
ANURAG SRIVASTAVA ◽  
BODDEPALLI SANTHIBHUSHAN ◽  
PANKAJ DOBWAL
Keyword(s):  
Coulomb Blockade ◽  
Density Functional ◽  
Stability Diagram ◽  
Single Electron ◽  
Single Electron Transistor ◽  
Functional Theory ◽  
Charge Stability ◽  
Anthracene Molecule ◽  
The Stability ◽  
Experimental Values

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.

Evaluation of Non-Vibrating Utility Burner/Furnace Systems for Resistance to Thermoacoustic Oscillations

2006 ◽  
Author(s):  
Frantisek L. Eisinger ◽  
Robert E. Sullivan
Keyword(s):  
Design Process ◽  
Axial Direction ◽  
Stability Diagram ◽  
Stable Range ◽  
Design Engineers ◽  
Secondary Role ◽  
The Stability ◽  
Thermoacoustic Oscillations

Six burner/furnace systems which operated successfully without vibration are evaluated for resistance to thermoacoustic oscillations. The evaluation is based on the Rijke and Sondhauss models representing the combined burner/furnace (cold/hot) thermoacoustic systems. Frequency differences between the lowest vulnerable furnace acoustic frequencies in the burner axial direction and those of the systems’ Rijke and Sondhauss frequencies are evaluated to check for resonances. Most importantly, the stability of the Rijke and Sondhauss models is checked against the published design stability diagram of Eisinger [1] and Eisinger and Sullivan [2]. It is shown that the resistance to thermoacoustic oscillations is adequately defined by the published design stability diagram to which the evaluated cases generally adhere. Once the system falls into the stable range, the frequency differences or resonances appear to play only a secondary role. It is concluded, however, that in conjunction with stability, the primary criterion, sufficient frequency separations shall also be maintained in the design process to preclude resonances. The paper provides sufficient details to aid the design engineers.

scholarly journals Stability analysis of magnetic fluids in the presence of an oblique field and mass and heat transfer

2020 ◽  
Vol 330 ◽  
pp. 01035
Author(s):  
Rabah Djeghiour ◽  
Bachir Meziani
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Magnetic Fluids ◽  
Physical Parameters ◽  
Stability Diagrams ◽  
Stability And Instability ◽  
Mass And Heat Transfer ◽  
Model Equations ◽  
The Stability ◽  
Oblique Magnetic Field

In this paper, we investigate an analysis of the stability of a basic flow of streaming magnetic fluids in the presence of an oblique magnetic field is made. We have use the linear analysis of modified Kelvin-Helmholtz instability by the addition of the influence of mass transfer and heat across the interface. Problems equations model is presented where nonlinear terms are neglected in model equations as well as the boundary conditions. In the case of a oblique magnetic field, the dispersion relation is obtained and discussed both analytically and numerically and the stability diagrams are also obtained. It is found that the effect of the field depends strongly on the choice of some physical parameters of the system. Regions of stability and instability are identified. It is found that the mass and heat transfer parameter has a destabilizing influence regardless of the mechanism of the field.

Sign in / Sign up

Export Citation Format

Share Document