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Showing 1 to 20 of 210 for “"Linear stability"”.
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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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Shear instabilities in stellar objects: linear stability and non-linear evolution
… can still be present. Therefore, studying the stability of shear flows and their non-linear evolution in a fully compressible polytropic atmosphere provides a fundamental understanding of potential motion in stellar interiors and is the main focus of this thesis. To commence the investigations …
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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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Hydrodynamic linear stability of the two-dimensional bluff-body wake through modal analysis and initial-value problem formulation
The stability of the two-dimensional wake behind a circular cylinder - a free flow of general interest in differing applications (from aerodynamics to environmental physics and biology) - is studied by means of two different but complementary theoretical methods. The first part of the work is …
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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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A numerical investigation of the compressible mixing layer
… muong layer has been investigated by means of linear stability theory and two- and three-dimensional direct numerical simulations of the compressible Navier-Stokes equations. The objective was to identify the effects of compressibility on a building-block fluid flow, with applications to …
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The effects of thermal radiation on dry convection
… theoretical and numerical analyses of the stability properties, and various analyses of the weakly nonlinear convecting state. We prove that in these models, convection arises as monotonically growing cells, not as an oscillatory instability. That is, we prove exchange of stabilities. We …
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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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Spinning modes in orderly jet structure and jet noise
… over the first twelve diameters of the jet. A linear stability analysis of higher order azimuthally coherent wave-like disturbances on a slowly diverging mean flow has been used to predict the axial-growth rates, phase speeds and radial distributions of the flow characteristics in the forced …
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Partial singular integro-differential equations models for dryout in boilers
… stated and discussed. The resulting unsteady nonlinear singular integro-differential equation for the liquid film free surface is solved asymptotically and numerically (using some regularisation techniques) in the steady state case, for a number of industrially relevant cases. Predictions for the …
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Instability of steady and quasi-steady detonations
The stability properties and dynamic behavior of steady and quasi-steady detonation theories are investigated through linear stability analysis and numerical simulation. A general, unsteady, three-dimensional formulation of the reactive Euler equations in a shock-fitted reference frame is derived. …
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ΣΥΜΒΟΛΗ ΣΤΗΝ ΜΕΛΕΤΗ ΤΟΥ ΦΩΤΟΒΑΡΥΤΙΚΟΥ ΠΕΡΙΟΡΙΣΜΕΝΟΥ ΠΡΟΒΛΗΜΑΤΟΣ ΤΩΝ ΤΡΙΩΝ ΣΩΜΑΤΩΝ
… IN THE SECOND CHAPTER THE EXISTENCE,LOCATION AND LINEAR STABILITY OF THE EQUILIBRIUM POINTS OF THE PROBLEM IS STUDIED. IN THE THIRD CHAPTER THE EVOLUTION OF THE AREAS WHERE THE THIRD BODY IS ABLE TO MOVE ACCORDING TO THE VALUE OF THE INTEGRAL OF MOTION, WHEN ONLY ONE OF THE MAIN BODIES RADIATES. …
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Stability analysis of gravity-driven viscosity-stratified coating flows
This theoretical investigation presents the linear stability analysis of a gravity-driven and viscosity-stratified coating flow useful in covering a planar surface with one or more liquid layers. The challenging stability analysis of a coating flow on a curved substrate surface is discussed. The …
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Numerical Investigation of Tonal Noise on a Transitional Airfoil under Varying Conditions
… of attack. The purpose of this study is to use linear stability theory to study the growth of instabilities on the pressure and suction surfaces of airfoils for varying Re between 144,000 and 468,000 and angles of attack between 0˚ and 12˚. High accuracy 2D simulations based on an Implicit Large …
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Pattern formation in systems far from equilibrium
… to the dynamics of pattern formation in non-linear, dissipative systems far from equilibrium. The first problem addresses the dynamical mechanism of velocity and shape selection in dendritic crystal growth. Using the boundary-layer model of solidification, we demonstrate the new solvability …
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