scholarly journals Two-dimensional fluid model for calculating the natural vibration frequencies of axially symmetric hydro-shell systems

2017 ◽  
Author(s):  
В.А. Грибков ◽  
◽  
Р.А. Адаменко ◽  
Keyword(s):  
Natural Vibration ◽  
Fluid Model ◽  
Two Dimensional ◽  
Vibration Frequencies ◽  
Axially Symmetric

Numerical Analysis of Two-Phase Pipe Flow of Liquid Helium Using Multi-Fluid Model

2001 ◽  
Vol 123 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Jun Ishimoto ◽  
Mamoru Oike ◽  
Kenjiro Kamijo
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
Liquid Helium ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Numerical Results ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Normal Fluid

The two-dimensional characteristics of the vapor-liquid two-phase flow of liquid helium in a pipe are numerically investigated to realize the further development and high performance of new cryogenic engineering applications. First, the governing equations of the two-phase flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model are presented and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the two-phase flow of liquid helium is shown in detail, and it is also found that the phase transition of the normal fluid to the superfluid and the generation of superfluid counterflow against normal fluid flow are conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase. According to these theoretical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained should contribute to the realization of advanced cryogenic industrial applications.

scholarly journals On the Bean critical-state model in superconductivity

1996 ◽  
Vol 7 (3) ◽  
pp. 237-247 ◽  
Author(s):  
L. Prigozhin
Keyword(s):  
Variational Inequalities ◽  
Critical State ◽  
Existence And Uniqueness ◽  
Critical State Model ◽  
Type Ii ◽  
Two Dimensional ◽  
Axially Symmetric ◽  
Uniqueness Of The Solution ◽  
Type Ii Superconductivity ◽  
Special Case

We consider two-dimensional and axially symmetric critical-state problems in type-II superconductivity, and show that these problems are equivalent to evolutionary quasi-variational inequalities. In a special case, where the inequalities become variational, the existence and uniqueness of the solution are proved.

Simplified characteristics of active magnetic bearings

2002 ◽  
Vol 216 (5) ◽  
pp. 623-628 ◽  
Author(s):  
D J Peel ◽  
C M Bingham ◽  
Y Wu ◽  
D Howe
Keyword(s):  
Natural Vibration ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Viscous Damping ◽  
Vibration Frequencies ◽  
Active Magnetic Bearings ◽  
Complex Dynamic ◽  
Speed Range ◽  
Constant Coefficients ◽  
System Characteristics

Traditionally, active magnetic bearing (AMB) systems are designed as an integral component of machines having generally complex dynamic characteristics. An AMB supported rotor has been tested over a speed range that included system natural vibration frequencies. A linear stiffness and viscous damping AMB characteristic with constant coefficients was identified which was independent of the overall system characteristics and which can thus provide simple and transferable data for a machine designer.

Motion of a charged particle in superposed Heliotron and biconical cusp fields

1969 ◽  
Vol 3 (2) ◽  
pp. 255-267 ◽  
Author(s):  
M. P. Srivastava ◽  
P. K. Bhat
Keyword(s):  
Magnetic Field ◽  
Charged Particle ◽  
Magnetic Moment ◽  
Particle Trajectory ◽  
Three Dimensional ◽  
Equation Of Motion ◽  
Neutral Point ◽  
Two Dimensional ◽  
Axially Symmetric ◽  
Hybrid Type

We have studied the behaviour of a charged particle in an axially symmetric magnetic field having a neutral point, so as to find a possibility of confining a charged particle in a thermonuclear device. In order to study the motion we have reduced a three-dimensional motion to a two-dimensional one by introducing a fictitious potential. Following Schmidt we have classified the motion, as an ‘off-axis motion’ and ‘encircling motion’ depending on the behaviour of this potential. We see that the particle performs a hybrid type of motion in the negative z-axis, i.e. at some instant it is in ‘off-axis motion’ while at another instant it is in ‘encircling motion’. We have also solved the equation of motion numerically and the graphs of the particle trajectory verify our analysis. We find that in most of the cases the particle is contained. The magnetic moment is found to be moderately adiabatic.

Weak solutions for generalized stationary Oldroyd-B fluid with a diffusive stress

2016 ◽  
Vol 23 (4) ◽  
pp. 469-475
Author(s):  
Hafedh Bousbih ◽  
Mohamed Majdoub
Keyword(s):  
Stress Tensor ◽  
Weak Solutions ◽  
Fluid Model ◽  
Three Dimensional ◽  
Shear Thickening ◽  
Bounded Domains ◽  
Two Dimensional ◽  
Existence Of Weak Solutions ◽  
Elastic Part ◽  
Viscosity Function

AbstractThis paper focuses on the analysis of the stationary case of incompressible viscoelastic generalized Oldroyd-B fluids derived in [2] by Bejaoui and Majdoub. The studied model is different from the classical Oldroyd-B fluid model in having a viscosity function which is shear-rate depending, and a diffusive stress added to the equation of the elastic part of the stress tensor. Under some conditions on the viscosity stress tensor and for a large class of models, we prove the existence of weak solutions in both two-dimensional and three-dimensional bounded domains for shear-thickening flows.

scholarly journals LOW- TO MID-FREQUENCY SCATTERING FROM ELASTIC OBJECTS ON A SAND SEA FLOOR: SIMULATION OF FREQUENCY AND ASPECT DEPENDENT STRUCTURAL ECHOES

2012 ◽  
Vol 20 (02) ◽  
pp. 1240007 ◽  
Author(s):  
MARIO ZAMPOLLI ◽  
AUBREY L. ESPANA ◽  
KEVIN L. WILLIAMS ◽  
STEVEN G. KARGL ◽  
ERIC I. THORSOS ◽  
...  
Keyword(s):  
Scattering Problem ◽  
Three Dimensional ◽  
Element Model ◽  
Propagation Model ◽  
Target Strength ◽  
Unexploded Ordnance ◽  
Two Dimensional ◽  
Axially Symmetric ◽  
Sea Floor ◽  
Spectral Integral

The scattering from roughly meter-sized targets, such as pipes, cylinders and unexploded ordnance shells in the 1–30 kHz frequency band is studied by numerical simulations and compared to experimental results. The numerical tool used to compute the frequency and aspect-dependent target strength is a hybrid model, consisting of a local finite-element model for the vicinity of the target, based on the decomposition of the three-dimensional scattering problem for axially symmetric objects into a series of independent two-dimensional problems, and a propagation model based on the wavenumber spectral integral representation of the Green's functions for layered media.

Influence of Gravity and Taper on the Vibration of a Standing Column

2012 ◽  
Vol 4 (04) ◽  
pp. 483-495 ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Cross Section ◽  
Numerical Stability ◽  
Natural Vibration ◽  
Vibration Frequencies ◽  
Stability Criteria ◽  
Initial Value ◽  
Vertical Column ◽  
Stability Boundaries ◽  
Section Shape ◽  
The Stability

AbstractThe stability and natural vibration of a standing tapered vertical column under its own weight are studied. Exact stability criteria are found for the pointy column and numerical stability boundaries are determined for the blunt tipped column. For vibrations we use an accurate, efficient initial value numerical method for the first three frequencies. Four kinds of columns with linear taper are considered. Both the taper and the cross section shape of the column have large influences on the vibration frequencies. It is found that gravity decreases the frequency while the degree of taper may increase or decrease frequency. Vibrations may occur in two different planes.

scholarly journals Finite elements apparatus in thin-walled rods dynamics problems

2018 ◽  
Vol 245 ◽  
pp. 08007 ◽  
Author(s):  
Vladimir Rybakov ◽  
Stanislav Dyakov ◽  
Daniil Sovetnikov ◽  
Artur Azarov ◽  
Sergey Ivanov
Keyword(s):  
Natural Vibration ◽  
Steel Structures ◽  
Vibration Frequencies ◽  
Construction Engineering ◽  
Shear Theory ◽  
Mass Matrices ◽  
Element System ◽  
Mathematical Problems ◽  
Thin Walled ◽  
Dynamics Problems

The calculation of thin-walled rods is extremely relevant problem of structural mechanics and not only from the scientific standpoint, but also due to the widespread use of so-called lightweight thin-walled steel structures for construction engineering sector. Regardless of a sufficiently large number of studies connected with the statics of thin-walled rods, the dynamics of such systems have not been thoroughly studied yet. Based on one of the forward-looking theories of calculation i.e. the semi-shear theory by Slicker, the paper provides a technique for solving the dynamics problems of thin-walled rods. The stiffness and mass matrices of the finite element system are obtained for linear approximation of the form functions, and the natural vibration frequencies of the rods are calculated. The obtained solution is accomplished by the extrapolation method of estimating the accuracy of numerical methods for solving mathematical problems.

A two-dimensional cochlear fluid model based on conformal mapping

2010 ◽  
Vol 128 (6) ◽  
pp. 3577-3584 ◽  
Author(s):  
Hannes Lüling ◽  
Jan-Moritz P. Franosch ◽  
J. Leo van Hemmen
Keyword(s):  
Conformal Mapping ◽  
Fluid Model ◽  
Two Dimensional ◽  
Model Based
Sign in / Sign up

Export Citation Format

Share Document