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Showing 1 to 20 of 25 for “"Linear Stability Theory"”.
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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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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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Evolution of an Acoustic Disturbance to Transition in the Boundary Layer on an Airfoil
… the design procedure, along with the theoretical stability characteristics of the airfoil will be presented in this paper. The experiment consisted of establishing the mean flow conditions, forcing two-dimensional Tollmien-Schlichting (T-S) waves in the boundary layer using modulated acoustic …
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Determination of Human Powered Helicopter Stability Characteristics Using Multi-Body System Simulation Techniques
… was developed as a method for determining the stability characteristics of a human powered helicopter(HPH) configurations. HPH stability remains a key component for meeting competition requirements, but has not been properly treated. Traditional helicopter dynamic analysis is not suited to the …
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Numerical Simulation Of Stratified Flows And Droplet Deformation In 2D Shear Flow Of Newtonian And Viscoelastic Fluids
… interfaces. The code uses the piecewise linear interface calculation method to reconstruct the interface, the continuous surface force formulation to model interfacial tension forces and utilizes the semi-implicit Stokes solver (enabling computations at low Reynolds numbers). 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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Magnetic Damping of Thermocapillary Convection in the Floating-Zone Growth of Semiconductor Crystals
… to run enough simulations to search for neutral stability as a function of magnetic field strength over the entire parameter space. To circumvent these difficulties, we have used matched asymptotic expansions, linear stability theory and numerics to characterize these flows. Some fundamental …
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Machine Learning Approaches to Data-Driven Transition Modeling
… models using data from computations based on linear stability theory. Such data provide strong correlation with the underlying physics governed by linearized disturbance equations. In the proposed transition model, a convolutional neural network-based model encodes information from boundary …
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A Reduced-Order Model Bi-Modal Excitation of a Supersonic Planar Jet
… at various streamwise locations. Locallyparallel linear stability theory is used to compute the shape assumptions for the coherent structure components involved in the set of ordinary differential equations. The set of ordinary differential equations is first solved for a single mode. The trends …
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Linear and nonlinear vibrational characteristics of oil lubricated journal bearings
… journal bearings and, in particular, the instability known as oil whirl, which is a self-excited oscillation induced by the hydrodynamic forces generated in the bearing. The thesis is divided into two parts. In Part 1, linear stability theory is used to determine the critical parameter …
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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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One-dimensional modelling of rock-ice avalanches: mathematical features, numerical solutions, and strategies to enlarge the hyperbolic range
… avalanche approaches. Finally, we apply the linear stability theory to the proposed model to investigate its potential ill-posedness in the ranges of the flow variables where hyperbolicity is lost. Since the proposed approach turns out to be ill-posed, the model regularization is performed by …
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Numerical simulation of dendritic growth of binary alloys
… solved, the results for the onset of interface instability and the prediction of the most unstable wavelength are in good agreement with linear stability theory. When applied to simulations of directional solidification of Pb-Sb alloys, the model generates dendritic structures and solute …
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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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Information Geometry For Nonlinear Least-Squares Data Fitting And Calculation Of The Superconducting Superheating Field
… resonance cavities. Parameter estimation by nonlinear least squares minimization is a ubiquitous problem that has an elegant geometric interpretation: all possible parameter values induce a manifold embedded within the space of data. The minimization problem is then to find the point on the …
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Instability of Oscillatory Flow in Ducts and Applications to Solid -Propellant Rocket Aeroacoustics
… as a mechanism of high-amplitude acoustic instability in solid propellant rockets, wherein finite amplitude acoustic motions can produce near-surface turbulence and lead to an enhanced propellant burning rate that couples with the chamber acoustics. Prediction of the threshold acoustic …
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Waves and turbulence in sustained stratified shear flows
… physical mechanisms at its origin by means of linear stability theory. Since Holmboe waves are found in the intermediate, transitional regime between laminar and turbulent flows, we conjecture that their structure may be relevant to more turbulent flows, where resembling structures are indeed …
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Fluid-structure interaction in compressible flows
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-03-28 without embargo terms
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The Dynamics of Geophysical and Astrophysical Turbulence
… these systems. We compare the behaviour of a nonlinear (NL) system to a quasilinear (QL) model in which eddy-eddy interactions are neglected. Both systems reveal a rich zoology of dynamics, nevertheless, key differences exist. The NL model admits the formation of systematically migrating jets, a …
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Flow and mixing in complex porous media
… the dynamics of the miscible viscous-fingering instability are investigated. It is found that the dynamics can be divided into three regimes: at early times, the flow is well described by linear stability theory; at intermediate times, the flow is dominated by non-linear finger interactions; and …
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