scholarly journals Structure Formation in Anisotropic Disks

2006 ◽  
Vol 2 (S235) ◽  
pp. 143-143
Author(s):  
Eduard Vorobyov ◽  
Christian Theis
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Disk Galaxies ◽  
Structural Elements ◽  
Small Perturbations ◽  
Gravitational Instabilities ◽  
Hydrodynamical Simulations ◽  
Axisymmetric Structures ◽  
Insight Into

The majority of normal disk galaxies are characterized by non-axisymmetric structures like spirals or bars. These structural elements have been widely discussed in the literature as a result of gravitational instabilities which are connected to growing density waves or global instabilities of disks. A first insight into the properties of galactic discs was provided by linear stability analysis. However, a disadvantage of linear stability analysis remained its restriction to small perturbations, both in amplitude and wavelength. Thus, numerical simulations, especially hydrodynamical and stellar-hydrodynamical simulations became a primary tool for the analysis of galactic evolution.

Linear Stability Analysis of a Collapsible-Tube Model

1999 ◽  
Author(s):  
P. Ruby Mawasha ◽  
Richard J. Gross ◽  
Ted Conway
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Tube Model ◽  
Collapsible Tube ◽  
Small Perturbations ◽  
Pressure Drops ◽  
Outlet Flow ◽  
Operation Control ◽  
State Pressure

Abstract A linear stability analysis is performed for a collapsible tube model consisting of a reservoir with inlet and outlet flow conditions. The downstream pressure in the collapsible regime is modeled as a cubic nonlinearity. From the nonlinear model, we assume small perturbations around the steady states and utilize Liapunov stability criteria to describe the linear model. Steady-state pressure drops, stable and unstable boundaries are determined analytically for ranges of mass flow rate and compressible volume in the reservoir. Mechanisms that give rise to unstable behavior of pressure and flow rates in collapsible tube systems are examined based on numerical results. The model also provide us with stable and unstable boundaries that may give us the insight on the operation, control, and safety of collapsible tube systems in biological systems such as veins, arteries etc.

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