Crossflow instability of a three-dimensional boundary layer is common cause transition in swept-wing flows. The boundary-layer flow modified by the presence finite-amplitude crossflow modes susceptible to high-frequency secondary instabilities, which are believed harbinger onset transition. role prediction theoretically examined for recent experimental data Reibert et al . (1996). Exploiting observation that underlying convectively unstable, non-linear parabolized stability equations used...

Computations for sharp cones, using the e N method with N=10, show that first oblique Tollmien-Schlichting mode is responsible transition at adiabatic wall conditions freestream Mach numbers up to about 7. For cold walls, two-dimensional second dominates process lower hypersonic due well-known destabilizing effect of cooling on

Nonlinear stability of a model swept-wing boundary layer, subject to crossflow instability, is investigated by numerically solving the governing partial differential equations. The three-dimensional layer unstable both stationary and travelling disturbances. calculations have been carried out for vortices computed wall vorticity pattern results in streamwise streaks which resemble quite well surface oil-flow visualizations experiments. Other features vortex development (half-mushroom...

The stability of three dimensional rotating disk flow and the effects Coriolis forces streamline curvature were investigated. It was shown that this analysis gives better growth rates than Orr-Sommerfeld equation. Results support numerical prediction number stationary vortices varies directly with Reynolds number.

The neutral curve for stationary vortex disturbances in rotating-disk flow is computed up to a Reynolds number of 10 7 using the sixth-order system linear stability equations which includes effects streamline curvature and Coriolis force. It found that has two minima: one at R = 285.36 (upper branch) other 440.88 (lower branch). At large numbers, upper branch tends Stuart's asymptotic solution while lower associated with wave angle corresponding direction zero mean wall shear.

Laminar–turbulent transition mechanisms for a supersonic boundary layer are examined by numerically solving the governing partial differential equations. It is shown that dominant mechanism at low Mach numbers associated with breakdown of oblique first-mode waves. The first stage in this process involves nonlinear interaction pair waves equal but opposite angles resulting evolution streamwise vortex. This can be described wave–vortex triad consisting and vortex whereby grow linearly while...

The parabolized stability equation (PSE) approach is employed to study linear and nonlinear compressible with an eye providing a capability for boundary-layer transition prediction in both 'quiet' 'disturbed' environments. governing equations are solved by rational parabolizing approximation the streamwise direction. Nonparallel flow effects studied first- second-mode disturbances. For oblique waves of first-mode type, departure from parallel results more pronounced as compared that...

An experimental study of the transitional flow over a flat disk rotating in quiescent ambient air has been conducted. Using digitized hot-wire data, axes stationary spiral vortices, which are primary instability mechanisms for flow, have mapped out terms both spatial coordinates and velocity fluctuations. Data presented clean with single, isolated roughness element. The data show that vortices generated at discrete disturbance sites on they propagate grow as wave packets. familiar vortex...

The instability of an infinite swept attachment line boundary layer is considered in the linear régime. basic three-dimensional flow shown to be susceptible travelling wave disturbances that propagate along line. effect suction on discussed and results suggest a wing can significantly stabilized by extremely small amounts suction. obtained are excellent agreement with available experimental observations.

High-temperature effects alter the physical and transport properties of a gas, air in particular, due to vibrational excitation gas dissociation, thus chemical reactions have be considered order compute flow field. Linear stability high-temperature boundary layers is investigated under assumption equilibrium this model labeled here as ‘‘real model.’’ In model, system equations remains same for perfect effect introduced only through mean property variations. Calculations are performed Mach 10...

The nonlinear development of stationary Görtler vortices leads to a highly distorted mean flow field where the streamwise velocity depends strongly not only on wall-normal but also spanwise coordinates. In this paper, inviscid instability is analysed by solving two-dimensional eigenvalue problem associated with governing partial differential equation. It found that subject fundamental odd and even (with respect vortex) unstable modes. mode, which was Hall & Horseman (1991), initially...

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The disturbance field induced due to a harmonic point source consists of discrete eigenmodes and continuous spectrum; these are studied by using generalized Fourier transform techniques. For supersonic boundary layer, there exist seven branches the spectrum in complex wavenumber space, four which (two acoustic waves, one vorticity wave entropy wave) contribute flow downstream source. spring off from at some critical Reynolds numbers. results for Mach 2 4.5 layers show that receptivity...

The stability of the incompressible attachment-line boundary layer is studied by solving a partial-differential eigenvalue problem. basic flow near leading edge taken to be swept Hiemenz which represents an exact solution Navier-Stokes (N-S) equations. Previous theoretical investigations considered special class two-dimensional disturbances in chordwise variation disturbance velocities mimics and renders system ordinary-differential equations Orr-Sommerfeld type. this sixth-order Hall, Malik...

Research Article| July 01, 2016 Shortening rate and Holocene surface rupture on the Riasi fault system in Kashmir Himalaya: Active thrusting within Northwest Himalayan orogenic wedge Y. Gavillot; Gavillot 1College of Earth, Ocean, Atmospheric Sciences, Oregon State University, Corvallis, 97331, USA †Present address: 1115 NW 35th Street, 97330, USA; ygavillot@gmail.com. Search for other works by this author on: GSW Google Scholar A. Meigs; Meigs D. Yule; Yule 2Department Geological California...

The instability of a three-dimensional attachment-line boundary layer is considered in the nonlinear regime. Using weakly theory, it found that, apart from small interval near (linear) critical Reynolds number, finite-amplitude solutions bifurcate subcritically upper branch neutral curve. time-dependent Navier–Stokes equations for flow have been solved using Fourier–Chebyshev spectral method and subcritical at wavenumbers that correspond to branch. Both theory numerical calculations show...

The problem of the stability a three-dimensional laminar boundary layer formed on curved surface is considered. A calculation scheme, which takes account curvature flow streamlines and proposed for prediction development small amplitude temporal disturbances. Computations have been performed over windward face an infinitely long yawed cylinder comparisons made with experimental data. These indicate that theory correctly predicts many features unstable flow. also suggests transition, in this...

A spanwise-periodic computation of a turbulent flow past Gaussian bump is performed in the form hybrid direct numerical simulation and wall-resolved large-eddy simulation. fourth-order spatially accurate solver employed to perform simulation, using 10.2 billion grid points for Reynolds number 170,000 based on height. The key findings from are reported acceleration deceleration regions associated with shape. Significant anisotropy normal stresses, along both wall-normal streamwise directions,...