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Showing 1 to 20 of 122 for “"linear stability analysis"”.
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Linear stability analysis of non-reacting and reacting elliptical jets
A spatial linear stability analysis of circular and elliptical jets has been carried out. For the circular jet, the Michalke's shooting method has been extended to the case with a swirling basic flow. For the elliptical jet, an algebraic eigenvalue problem has been formulated by applying the …
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Comparison of Second Order Conformal Symplectic Schemes with Linear Stability Analysis
Numerical methods for solving linearly damped Hamiltonian ordinary differential equations are analyzed and compared. The methods are constructed from the well-known Störmer-Verlet and implicit midpoint methods. The structure preservation properties of each method are shown analytically and …
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Investigation of Dynamics in Turbulent Swirling Flows Aided by Linear Stability Analysis
… largely just downstream of the sudden expansion. Linear stability analysis was used to help in the interpretation of the observed dynamics. Although, as implemented here (using the parallel flow assumption), the analysis was not successful in quantitatively matching the experimentally observed …
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Linear stability analysis of circular jets: integer, fractional, and multiple mode excitation
The linear stability analysis of Huang [1995] has been adapted to ignore the effects of swirl, and to allow calculation of the eigenvalues and eigenfunctions for integer, fractional, and multiple modes of excitation. The investigation was intended to be exploratory; to gain the best possible …
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Linear Stability Analysis of a Rijke Tube and Modeling of Turbulent Combustion Using Dynamic Well-Stirred Reactors
In the first part of this work, instability is correctly predicted for a Rijke tube with a new two-term acoustic forcing term derived from a one-dimensional flame dynamics model. The new two-term acoustic forcing term, which is comprised of the summation of chemical heat release rate and heat …
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Jet mixing: the role of numerical flow visualization
… explore the results of numerical simulations and linear stability analysis. Because the results of preliminary numerical flow simulations were so topologically complex, linear stability analysis (LSA) was employed to generate simpler flows. These results provided important insight into the early …
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Numerical simulations of elliptical jets: a study of jet entrainment
… algorithm and initialized with the results of a linear stability analysis with the objective of investigating the entrainment process and explaining the dependence of the entrainment on jet geometry. Through the medium of scientific visualization, mechanisms responsible for entrainment have been …
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Stability of plane-front and dendritic solidification of binary liquids: The effects of rotation
… solidified by cooling from below are studied by linear stability analysis. Use of uniform rotation about the vertical to suppress onset of buoyancy-driven convection is considered for plane-front solidification (PFS) and dendritic solidification (DeS).
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A theoretical study of stellart pulsations in young brown dwarfs
… PB05 study presents results of a non-adiabatic linear stability analysis showing that young brown dwarfs should become pulsationally unstable during the deuterium burning phase of their evolution.
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Numerical studies of the flow around an airfoil at low Reynolds number
… of direct numerical simulation (DNS) and linear stability analysis. The behaviour of laminar separation bubbles formed on a NACA-0012 airfoil at Rec = 5 £ 104 and incidence 5± is investigated. Initially volume forcing is introduced in order to promote transition to turbulence. After …
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Experimental and gyrokinetic studies of impurity transport in the core of Alcator C-Mod Plasmas
… simulated emission. These measurements and data analysis methodology allowed for determination of impurity transport coefficient profiles with realistic errors from 0.0 </= r/a </= 0.6. The gyrokinetic co(le, GYRO, was use to analyze the same discharges. Motivated by linear stability analysis and …
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Non-linear finite element thermo-hydrodynamic analysis of oil ring seals used in high pressure centrifugal compressors
The analysis of oil seals is of great concern for the proper design of high pressure centrifugal compressors, because they can have significant influence on the dynamic stability of the compressor rotor. The lack of adequate analytical tools highlight the need for this type of study. An analytical …
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Effect of heating on sound radiated from a two-dimensional mixing layer
The effect of heating on sound radiated by instability waves in a two-dimensional mixing layer is studied. A linear stability theory coupled with linearized Euler calculations are used to compute the amplitude of the instability wave and its associated sound field. The linear stability analysis …
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Dewetting of thin solid films
… of solutions, numerical simulations and linear stability analysis of the dewetting front. We start with the formulation of a two-dimensional anisotropic phase field model for solid state dewetting on a solid substrate. The evolution is described by a Cahn-Hilliard type equation with a …
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Robustness of adaptive control systems to unmodeled dynamics : a describing function viewpoint
… extensive first-principle based arguments and/or analysis of the parameter trajectory is employed. An alternative to such analysis, albeit approximate, is to use the well-known Describing Function (DF) method. In doing so, the analysis of the robust adaptive control problem becomes tractable and …
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Molecular Beam Epitaxy: A Thermomechanical Treatment
We perform a linear stability analysis, and consider the dependence of the growth rate of instability on the wave number. This dispersion relation is a function of many parameters that describe the elasticity and chemistry of the film and substrate. The analysis permits us to recover the classical …
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Unsteady incompressible viscous flow past stationary, pitching or oscillating airfoil leading edges
… is a feature of the high-frequency Rayleigh instability. A study of the Reynolds-number scaling of the wavelength of these instabilities yielded a value reasonably close to that predicted by theory. A linear stability analysis of the boundary layer over the parabola was carried out to map the …
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Analysis of pattern dynamics for a nonlinear model of the human cortex via bifurcation theories
… and electrical (gap-junction) synapses. The linear stability analysis of the model equations predict the emergence of a Turing instability (in which separated areas of the cortex become activated) when gap-junction diffusivity is increased above a critical level. In addition, a Hopf …
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Viscous fingering instabilities and gravity currents.–—
This thesis examines the possible instability of radially spreading interfaces to the formation of fingers that break the axial symmetry. A well-known example of this occurs when a less viscous fluid displaces a more viscous immiscible fluid either in a porous medium or in a Hele-Shaw cell, which …
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A matrix-free numerical bifurcation method applied to sheared annular electroconvection
… systems based on numerical integration, and a linear stability analysis that identifies the local behaviour of the flow.
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