A study of the stability of the Z pinch under fusion conditions using the Hall fluid model

1984 ◽  
Vol 27 (12) ◽  
pp. 2886 ◽  
Author(s):  
M. Coppins ◽  
D. J. Bond ◽  
M. G. Haines
Keyword(s):  
Fluid Model ◽  
The Stability ◽  
Z Pinch

scholarly journals Dynamics of dusty vortices – I. Extensions and limitations of the terminal velocity approximation

2019 ◽  
Vol 488 (4) ◽  
pp. 5290-5299 ◽  
Author(s):  
Francesco Lovascio ◽  
Sijme-Jan Paardekooper
Keyword(s):  
Fluid Model ◽  
Velocity Model ◽  
Terminal Velocity ◽  
Viscous Stress Tensor ◽  
Spatial Convergence ◽  
Two Fluid Model ◽  
Numerical Solver ◽  
The Stability ◽  
Velocity Approximation ◽  
Protoplanetary Discs

ABSTRACT Motivated by the stability of dust laden vortices, in this paper we study the terminal velocity approximation equations for a gas coupled to a pressureless dust fluid and present a numerical solver for the equations embedded in the FARGO3D hydrodynamics code. We show that for protoplanetary discs it is possible to use the barycentre velocity in the viscous stress tensor, making it trivial to simulate viscous dusty protoplanetary discs with this model. We also show that the terminal velocity model breaks down around shocks, becoming incompatible with the two-fluid model it is derived from. Finally we produce a set of test cases for numerical schemes and demonstrate the performance of our code on these tests. Our implementation embedded in FARGO3D using an unconditionally stable explicit integrator is fast, and exhibits the desired second-order spatial convergence for smooth problems.

Stability of a Thermodynamically Coherent Multiphase Model

2003 ◽  
Vol 13 (10) ◽  
pp. 1463-1487
Author(s):  
B. Després ◽  
F. Lagoutière ◽  
D. Ramos
Keyword(s):  
Conservation Laws ◽  
Numerical Scheme ◽  
Fluid Model ◽  
Multiphase Model ◽  
Physical Domain ◽  
Rarefaction Waves ◽  
Phase Models ◽  
The Stability ◽  
Multi Phase ◽  
Dimension One

We analyze a hyperbolic system of conservation laws in dimension one, which is a drastic simplification of a multi-phase or multi-velocity fluid model. The physical domain of hyperbolicity is bounded, which is a characteristic of multi-phase models. Our main result is the stability of the domain of hyperbolicity. Due to the degeneracy of the model on the boundary of the hyperbolicity domain, rarefaction waves are not unique. We also propose a numerical scheme for approximate resolution of the model and prove the stability of this scheme.

Rotordynamic Stability Under Partial Admission Conditions in a Large Power Steam Turbine

2009 ◽  
Author(s):  
Lin Gao ◽  
Yiping Dai ◽  
Zhiqiang Wang ◽  
Yatao Xu ◽  
Qingzhong Ma
Keyword(s):  
Steam Turbine ◽  
Fluid Model ◽  
Rotor System ◽  
System Stability ◽  
Steam Turbines ◽  
Large Power ◽  
Control Stage ◽  
Partial Admission ◽  
The Stability ◽  
Load Conditions

At present, the majority of power steam turbines operate under part-load conditions during most of their working time in accordance with the fluctuation of power supply. The load governing method may cause partial admission in control stage and even some pressure stages, which impacts much on the stability of the rotor system. In this paper, CFD and FEM method were used to analyze the effect of partial admission on rotor system stability. A new approach is proposed to simplify the 3D fluid model for a partial admission control stage. Rotordynamic analysis was carried out to test the stability of the HP rotor of a 600 MW steam turbine under different load conditions. 13 different governing modes on the rotor stability were conducted and data were analyzed. It is found that rotor stability varies significantly with different governing modes and mass flow rates, which is consistent with the operation. Asymmetric fluid forces resulted from partial admission cause a fluctuation of the dynamic characteristics of the HP bearings, which consequently affect the stability of the rotor system. One of the nozzle governing modes in which the diagonal valves open firstly is demonstrated as the optimal mode with the maximum system stability. The optimization has been applied to 16 power generation units in China and result in improved rotor stabilities.

The stability of the Couette flow of helium II

1988 ◽  
Vol 197 ◽  
pp. 551-569 ◽  
Author(s):  
C. F. Barenghi ◽  
C. A. Jones
Keyword(s):  
Couette Flow ◽  
Fluid Model ◽  
Taylor Instability ◽  
Mutual Friction ◽  
Helium Ii ◽  
Two Fluid Model ◽  
The Stability ◽  
Superfluid Vortices ◽  
Two Fluid

The stability of Couette flow in HeII is considered by an analysis of the HVBK equations. These equations are based on the Landau two-fluid model of HeII and include mutual friction between the normal and superfluid components, and the vortex tension due to the presence of superfluid vortices. We find that the vortex tension strongly affects the nature of the Taylor instability at temperatures below ≈ 2.05 K. The effect of the vortex tension is to make non-axisymmetric modes the most unstable, and to make the critical axial wavelength very long.We compare our results with experiments.

scholarly journals A multi-fluid model of the magnetopause

2019 ◽  
Author(s):  
Roberto Manuzzo ◽  
Francesco Califano ◽  
Gerard Belmont ◽  
Laurence Rezeau
Keyword(s):  
Solar Wind ◽  
Electromagnetic Fields ◽  
Large Scale ◽  
Fluid Model ◽  
Analytic Model ◽  
Equilibrium Equations ◽  
Magnetic Field Topology ◽  
Initial Equilibrium State ◽  
Magnetospheric Multiscale Mission ◽  
The Stability

Abstract. Observation of the solar wind – magnetosphere boundary provides a unique opportunity to investigate the physics underlying the interaction between two collisionless magnetized plasmas with different temperature, density and magnetic field topology. Their mixing across the interface as well as the boundary dynamics are affected by the development of fluid (and kinetic) instabilities driven by large scale inhomogeneities in particle and electromagnetic fields. Building up a realistic initial equilibrium state of the magnetopause according to observations is still a challenge nowadays. In this paper we address the modeling of the particles and electromagnetic fields configuration across the Earth's magnetopause by means of a three-fluid analytic model. The model relies on one hot and one cold ion population and on a neutralizing electron population. The goal is to build up an analytic model able to reproduce as closely as possible the observations. Some parameters of the model are set by using a fit procedure aiming at minimizing their difference with respect to experimental data provided by the Magnetospheric MultiScale mission. All the other profiles, concerning the electron pressure and the relative densities of the cold and hot ion populations, are calculated in order to satisfy the fluid equilibrium equations. Finally, by means of a new tri-fluid code, we have checked the stability of the large-scale equilibrium model for a given experimental case and given the proof that the system is unstable to reconnection. This model could be of interest for the interpretation of satellite results and for the study of the dynamics at the boundary between the Magnetosphere and the solar wind.

On The Stability Of The Magnetized Noh Z-Pinch Problem*

2017 ◽  
Author(s):  
S.T. Zalesak ◽  
A.L. Velikovich ◽  
J.L. Giuliani ◽  
Andrey Beresnyak
Keyword(s):  
The Stability ◽  
Z Pinch

scholarly journals The stability of the high-density z-pinch

1989 ◽  
Author(s):  
A. H. Glasser ◽  
R. A. Nebel
Keyword(s):  
High Density ◽  
The Stability ◽  
Z Pinch

scholarly journals Coronal fluid-dynamics in laser fusion

1989 ◽  
Vol 7 (2) ◽  
pp. 219-228 ◽  
Author(s):  
Juan R. Sanmartín
Keyword(s):  
Fluid Dynamics ◽  
Fluid Model ◽  
Laser Fusion ◽  
Additional Parameter ◽  
Direct Drive ◽  
Magnetic Field Generation ◽  
One Dimensional ◽  
Two Fluid Model ◽  
Inverse Bremsstrahlung Absorption ◽  
The Stability

The fluid-dynamics of the corona ejected by laser-fusion targets in the direct-drive approach (thermal radiation and atomic physics unimportant) is discussed. A two-fluid model involves inverse bremsstrahlung absorption, refraction, different ion and electron temperatures with energy exchange, different ion and electron velocities and magnetic field generation, and their effect on ion-electron friction and heat flux. Four dimensionless parameters determine coronal regimes for one-dimensional flows under uniform irradiation. One additional parameter is involved in two-dimensional problems, including the stability of one-dimensional flows, and the smoothing of non-uniform driving.

scholarly journals Rayleigh-Bénard convection in an elastico-viscous Walters’ (model B’) nanofluid layer

2015 ◽  
Vol 63 (1) ◽  
pp. 235-244 ◽  
Author(s):  
G.C. Rana ◽  
R. Chand
Keyword(s):  
Fluid Model ◽  
Normal Mode Analysis ◽  
Sufficient Conditions ◽  
Lewis Number ◽  
Horizontal Layer ◽  
Linear Stability Theory ◽  
Mode Analysis ◽  
Physical Parameters ◽  
Onset Of Convection ◽  
The Stability

Abstract In this study, the onset of convection in an elastico-viscous Walters’ (model B’) nanofluid horizontal layer heated from below is considered. The Walters’ (model B’) fluid model is employed to describe the rheological behavior of the nanofluid. By applying the linear stability theory and a normal mode analysis method, the dispersion relation has been derived. For the case of stationary convection, it is observed that the Walters’ (model B’) elastico-viscous nanofluid behaves like an ordinary Newtonian nanofluid. The effects of the various physical parameters of the system, namely, the concentration Rayleigh number, Prandtl number, capacity ratio, Lewis number and kinematics visco-elasticity coefficient on the stability of the system has been numerically investigated. In addition, sufficient conditions for the non-existence of oscillatory convection are also derived.

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