Journal articles: 'Tollmien-Schlichting wave'

1

DAVIES, CHRISTOPHER, and PETER W. CARPENTER. "Instabilities in a plane channel flow between compliant walls." Journal of Fluid Mechanics 352 (December 10, 1997): 205–43. http://dx.doi.org/10.1017/s0022112097007313.

Full text

Abstract:

The stability of plane channel flow between compliant walls is investigated for disturbances which have the same symmetry, with respect to the channel centreline, as the Tollmien–Schlichting mode of instability. The interconnected behaviour of flow-induced surface waves and Tollmien–Schlichting waves is examined both by direct numerical solution of the Orr–Sommerfeld equation and by means of an analytic shear layer theory. We show that when the compliant wall properties are selected so as to give a significant stability effect on Tollmien–Schlichting waves, the onset of divergence instability can be severely disrupted. In addition, travelling wave flutter can interact with the Tollmien–Schlichting mode to generate a powerful instability which replaces the flutter instability identified in studies based on a potential mean-flow model. The behaviour found when the mean-flow shear layer is fully accounted for may be traced to singularities in the wave dispersion relation. These singularities can be attributed to solutions which represent Tollmien–Schlichting waves in rigid-walled channels. Such singularities will also be found in the dispersion relation for the case of Blasius flow. Thus, similar behaviour can be anticipated for Blasius flow, including the disruption of the onset of divergence instability. As a consequence, it seems likely that previous investigations for Blasius flow will have yielded very conservative estimates for the optimal stabilization that can be achieved for Tollmien–Schlichting waves for the purposes of laminar-flow control.

APA, Harvard, Vancouver, ISO, and other styles

2

DAVIES, CHRISTOPHER, and PETER W. CARPENTER. "Numerical simulation of the evolution of Tollmien–Schlichting waves over finite compliant panels." Journal of Fluid Mechanics 335 (March 25, 1997): 361–92. http://dx.doi.org/10.1017/s0022112096004636.

Full text

Abstract:

The evolution of two-dimensional Tollmien–Schlichting waves propagating along a wall shear layer as it passes over a compliant panel of finite length is investigated by means of numerical simulation. It is shown that the interaction of such waves with the edges of the panel can lead to complex patterns of behaviour. The behaviour of the Tollmien–Schlichting waves in this situation, particularly the effect on their growth rate, is pertinent to the practical application of compliant walls for the delay of laminar–turbulent transition. If compliant panels could be made sufficiently short whilst retaining the capability to stabilize Tollmien–Schlichting waves, there is a good prospect that multiple-panel compliant walls could be used to maintain laminar flow at indefinitely high Reynolds numbers.We consider a model problem whereby a section of a plane channel is replaced with a compliant panel. A growing Tollmien–Schlichting wave is then introduced into the plane, rigid-walled, channel flow upstream of the compliant panel. The results obtained are very encouraging from the viewpoint of laminar-flow control. They indicate that compliant panels as short as a single Tollmien–Schlichting wavelength can have a strong stabilizing effect. In some cases the passage of the Tollmien–Schlichting wave over the panel edges leads to the excitation of stable flow-induced surface waves. The presence of these additional waves does not appear to be associated with any adverse effect on the stability of the Tollmien–Schlichting waves. Except very near the panel edges the panel response and flow perturbation can be represented by a superposition of the Tollmien–Schlichting wave and two other eigenmodes of the coupled Orr–Sommerfeld/compliant-wall eigensystem.The numerical scheme employed for the simulations is derived from a novel vorticity–velocity formulation of the linearized Navier–Stokes equations and uses a mixed finite-difference/spectral spatial discretization. This approach facilitated the development of a highly efficient solution procedure. Problems with numerical stability were overcome by combining the inertias of the compliant wall and fluid when imposing the boundary conditions. This allowed the interactively coupled fluid and wall motions to be computed without any prior restriction on the form taken by the disturbances.

APA, Harvard, Vancouver, ISO, and other styles

3

Baines, Peter G., Sharan J. Majumdar, and Humio Mitsudera. "The mechanics of the Tollmien-Schlichting wave." Journal of Fluid Mechanics 312 (April 10, 1996): 107–24. http://dx.doi.org/10.1017/s0022112096001930.

Full text

Abstract:

We describe a mechanistic picture of the essential dynamical processes in the growing Tollmien-Schlichting wave in a Blasius boundary layer and similar flows. This picture depends on the interaction between two component parts of a disturbance (denoted ‘partial modes’), each of which is a complete linear solution in some idealization of the system. The first component is an inviscid mode propagating on the vorticity gradient of the velocity profile with the free-slip boundary condition, and the second, damped free viscous modes in infinite uniform shear with the no-slip condition. There are two families of these viscous modes, delineated by whether the phase lines of the vorticity at the wall are oriented with or against the shear, and they are manifested as resonances in a forced system. The interaction occurs because an initial ‘inviscid’ disturbance forces a viscous response via the no-slip condition at the wall. This viscous response is large near the resonance associated with the most weakly damped viscous mode, and in the unstable parameter range it has suitable phase at the outer part of the boundary layer to increase the amplitude of the inviscid partial mode by advection.

APA, Harvard, Vancouver, ISO, and other styles

4

Ustinov, M. V. "Tollmien-Schlichting wave generation by flow turbulence." Fluid Dynamics 49, no. 4 (July 2014): 468–80. http://dx.doi.org/10.1134/s0015462814040073.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Lüdeke, H., and R. von Soldenhoff. "Direct numerical simulation of TS-waves over suction panel steps from manufacturing tolerances." CEAS Aeronautical Journal 12, no. 2 (March 4, 2021): 261–71. http://dx.doi.org/10.1007/s13272-021-00496-9.

Full text

Abstract:

AbstractTo determine allowable tolerances between successive suction panels at hybrid laminar wings with suction surfaces, direct numerical simulations of Tollmien–Schlichting waves over different steps are carried out for realistic suction rates on a wind tunnel configuration. Simulations at given suction panel positions over forward and backward facing steps are carried out by the use of a high-order method for the direct simulation of Tollmien–Schlichting wave growth. Comparisons between high-fidelity direct numerical simulations and quick linear stability calculations have shown capabilities and limits of the well-validated linear stability theory design approach.

APA, Harvard, Vancouver, ISO, and other styles

6

Downs, Robert S., and Jens H. M. Fransson. "Tollmien–Schlichting wave growth over spanwise-periodic surface patterns." Journal of Fluid Mechanics 754 (July 30, 2014): 39–74. http://dx.doi.org/10.1017/jfm.2014.377.

Full text

Abstract:

AbstractA novel type of surface roughness is deployed in a zero-pressure-gradient boundary layer with the goal of delaying the onset of laminar-to-turbulent transition for drag reduction purposes. This proof-of-concept experiment relies on forcing phase-triggered Tollmien–Schlichting (TS) waves across a range of initial amplitudes to produce amplified boundary-layer disturbances in a controlled and repeatable manner. Building on earlier work demonstrating attenuation of forced disturbances and delay of transition with spanwise arrays of discrete roughness and miniature vortex generators (MVGs), the present work seeks a roughness shape which might find success in a wider range of flows. Toward that end, streamwise-elongated humps are regularly spaced in the spanwise direction to form a wavy wall. By direct modulation of the mean flow, growth rates of the forced disturbances are increased or decreased, depending on the roughness configuration. Boundary-layer velocity measurements with hot-wire probes have been performed in a parametric study of the effects of roughness-field geometry and forcing amplitude on TS-wave growth and transition. The roughness field proves detrimental to passive flow control efforts in some configurations, while a reduction in the TS-wave amplitudes compared with the smooth-wall reference case is observed at other conditions. Substantial delays in the onset of transition are demonstrated when TS waves are forced with large amplitudes.

APA, Harvard, Vancouver, ISO, and other styles

7

Akylas, T. R., and N. Toplosky. "The sound field of a Tollmien–Schlichting wave." Physics of Fluids 29, no. 3 (1986): 685. http://dx.doi.org/10.1063/1.865919.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Hall, P., and F. T. Smith. "On strongly nonlinear vortex/wave interactions in boundary-layer transition." Journal of Fluid Mechanics 227 (June 1991): 641–66. http://dx.doi.org/10.1017/s0022112091000289.

Full text

Abstract:

The interactions between longitudinal vortices and accompanying waves considered here are strongly nonlinear, in the sense that the mean-flow profile throughout the boundary layer is completely altered from its original undisturbed state. Nonlinear interactions between vortex flow and Tollmien-Schlichting waves are addressed first, and some analytical and computational properties are described. These include the possibility in the spatial-development case of a finite-distance break-up, inducing a singularity in the displacement thickness. Second, vortex/Rayleigh-wave nonlinear interactions are considered for the compressible boundary layer, along with certain special cases of interest and some possible solution properties. Both types, vortex/Tollmien-Schlichting and vortex/Rayleigh, are short-scale/long-scale interactions and they have potential applications to many flows at high Reynolds numbers. Their strongly nonlinear nature is believed to make them very relevant to fully fledged transition to turbulence.

APA, Harvard, Vancouver, ISO, and other styles

9

Mohammadi, A., H. V. Moradi, and J. M. Floryan. "New instability mode in a grooved channel." Journal of Fluid Mechanics 778 (August 10, 2015): 691–720. http://dx.doi.org/10.1017/jfm.2015.399.

Full text

Abstract:

It is known that longitudinal grooves may stabilize or destabilize the travelling wave instability in a channel flow depending on the groove wavenumber. These waves reduce to the classical Tollmien–Schlichting waves in the absence of grooves. It is shown that another class of travelling wave instability exists if grooves with sufficiently high amplitude and proper wavelengths are used. It is demonstrated that the new instability mode is driven by the inviscid mechanism, with the disturbance motion having the form of a wave propagating in the streamwise direction with phase speed approximately four times larger than the Tollmien–Schlichting wave speed and with its streamwise wavelength being approximately twice the spanwise groove wavelength. The instability motion is concentrated mostly in the middle of the channel and has a planar character, i.e. the dominant velocity components are parallel to the walls. A significant reduction of the corresponding critical Reynolds number can be achieved by increasing the groove amplitude. Conditions that guarantee the flow stability in a grooved channel, i.e. the grooved surface behaves as a hydraulically smooth surface, have been identified.

APA, Harvard, Vancouver, ISO, and other styles

10

Deguchi, Kengo, and Andrew Walton. "Bifurcation of nonlinear Tollmien–Schlichting waves in a high-speed channel flow." Journal of Fluid Mechanics 843 (March 16, 2018): 53–97. http://dx.doi.org/10.1017/jfm.2018.137.

Full text

Abstract:

Plane Poiseuille flow has long served as the simplest testing ground for Tollmien–Schlichting wave instability. In this paper, we provide a comprehensive comparison of equilibrium Tollmien–Schlichting wave solutions arising from new high-resolution Navier–Stokes calculations and the corresponding predictions of various large-Reynolds-number asymptotic theories developed in the last century, such as double-deck theory, viscous nonlinear critical layer theory and strongly nonlinear critical layer theory. In the relatively small to moderate amplitude regime, the theories excellently predict the behaviour of the numerical solutions at Reynolds numbers of order $10^{6}$ and above, whilst for larger amplitudes our computations suggest the need for further asymptotic theories to be developed.

APA, Harvard, Vancouver, ISO, and other styles

11

Walton, A. G., and F. T. Smith. "Properties of strongly nonlinear vortex/Tollmien–Schlichting-wave interactions." Journal of Fluid Mechanics 244, no. -1 (November 1992): 649. http://dx.doi.org/10.1017/s0022112092003252.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Zelman, M. B., and I. I. Maslennikova. "Tollmien-Schlichting-wave resonant mechanism for subharmonic-type transition." Journal of Fluid Mechanics 252 (July 1993): 449–78. http://dx.doi.org/10.1017/s0022112093003830.

Full text

Abstract:

Disturbance interactions in wave triads and multiwave systems of various configurations are investigated to reveal the mechanism of laminar-turbulent transition in Blasius and pressure-gradient boundary layers. The averaging method of weakly nonlinear instability theory in quasi-parallel flows is applied. Tollmien-Schlichting-wave resonant interaction is shown to be the only leading mechanism of subharmonic (S)-type transition. The mechanism universally dominates in boundary layers excited by sufficiently small initial disturbances. The role of any other mode is inefficient. Weakly nonlinear models are concluded not to explain the K-type transition scenario. The results of the study are employed to interpret physical and numerical experimental data.

APA, Harvard, Vancouver, ISO, and other styles

13

Kerimbekov, Ruslan M., and Anatoly I. Ruban. "Receptivity of boundary layers to distributed wall vibrations." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1830 (April 26, 2005): 1145–55. http://dx.doi.org/10.1098/rsta.2005.1556.

Full text

Abstract:

Linear three-dimensional receptivity of boundary layers to distributed wall vibrations in the large Reynolds number limit ( Re →∞) is studied in this paper. The fluid motion is analysed by means of the multiscale asymptotic technique combined with the method of matched asymptotic expansions. The body surface is assumed to be perturbed by small-amplitude oscillations being tuned in resonance with the neutral Tollmien–Schlichting wave at a certain point on the wall. The characteristic length of the resonance region is found to be O( Re −3/16 ), which follows from the condition that the boundary-layer non-parallelism and the wave amplitude growth have the same order of magnitude. The amplitude equation is derived as a solvability condition for the inhomogeneous boundary-value problem. Investigating detuning effects, we consider perturbations in the form of a wave packet with a narrow O( Re −3/16 ) discrete or continuous spectrum concentrated near the resonant wavenumber and frequency. The boundary-layer laminarization based on neutralizing the oncoming Tollmien–Schlichting waves (or wave packets) is also discussed.

APA, Harvard, Vancouver, ISO, and other styles

14

Ruban, A. I., T. Bernots, and D. Pryce. "Receptivity of the boundary layer to vibrations of the wing surface." Journal of Fluid Mechanics 723 (April 16, 2013): 480–528. http://dx.doi.org/10.1017/jfm.2013.119.

Full text

Abstract:

AbstractIn this paper we study the generation of Tollmien–Schlichting waves in the boundary layer due to elastic vibrations of the wing surface. The subsonic flow regime is considered with the Mach number outside the boundary layer $M= O(1)$. The flow is investigated based on the asymptotic analysis of the Navier–Stokes equations at large values of the Reynolds number, $\mathit{Re}= {\rho }_{\infty } {V}_{\infty } L/ {\mu }_{\infty } $. Here $L$ denotes the wing section chord; and ${V}_{\infty } $, ${\rho }_{\infty } $ and ${\mu }_{\infty } $ are the free stream velocity, air density and dynamic viscosity, respectively. We assume that in the spectrum of the wing vibrations there is a harmonic that comes in to resonance with the Tollmien–Schlichting wave on the lower branch of the stability curve; this happens when the frequency of the harmonic is a quantity of the order of $({V}_{\infty } / L){\mathit{Re}}^{1/ 4} $. The wavelength, $\ell $, of the elastic vibrations of the wing is assumed to be $\ell \sim L{\mathit{Re}}^{- 1/ 8} $, which has been found to represent a ‘distinguished limit’ in the theory. Still, the results of the analysis are applicable for $\ell \gg L{\mathit{Re}}^{- 1/ 8} $ and $\ell \ll L{\mathit{Re}}^{- 1/ 8} $; the former includes an important case when $\ell = O(L)$. We found that the vibrations of the wing surface produce pressure perturbations in the flow outside the boundary layer, which can be calculated with the help of the ‘piston theory’, which remains valid provided that the Mach number, $M$, is large as compared to ${\mathit{Re}}^{- 1/ 4} $. As the pressure perturbations penetrate into the boundary layer, a Stokes layer forms on the wing surface; its thickness is estimated as a quantity of the order of ${\mathit{Re}}^{- 5/ 8} $. When $\ell = O({\mathit{Re}}^{- 1/ 8} )$ or $\ell \gg {\mathit{Re}}^{- 1/ 8} $, the solution in the Stokes layer appears to be influenced significantly by the compressibility of the flow. The Stokes layer on its own is incapable of producing the Tollmien–Schlichting waves. The reason is that the characteristic wavelength of the perturbation field in the Stokes layer is much larger than that of the Tollmien–Schlichting wave. However, the situation changes when the Stokes layer encounters a wall roughness, which are plentiful in real aerodynamic flows. If the longitudinal extent of the roughness is a quantity of the order of ${\mathit{Re}}^{- 3/ 8} $, then efficient generation of the Tollmien–Schlichting waves becomes possible. In this paper we restrict our attention to the case when the Stokes layer interacts with an isolated roughness. The flow near the roughness is described by the triple-deck theory. The solution of the triple-deck problem can be found in an analytic form. Our main concern is with the flow behaviour downstream of the roughness and, in particular, with the amplitude of the generated Tollmien–Schlichting waves.

APA, Harvard, Vancouver, ISO, and other styles

15

Duck, P. W., A. I. Ruban, and C. N. Zhikharev. "The generation of Tollmien-Schlichting waves by free-stream turbulence." Journal of Fluid Mechanics 312 (April 10, 1996): 341–71. http://dx.doi.org/10.1017/s0022112096002042.

Full text

Abstract:

The phenomenon of Tollmien-Schlichting wave generation in a boundary layer by free-stream turbulence is analysed theoretically by means of asymptotic solution of the Navier-Stokes equations at large Reynolds numbers (Re → ∞). For simplicity the basic flow is taken to be the Blasius boundary layer over a flat plate. Free-stream turbulence is taken to be uniform and thus may be represented by a superposition of vorticity waves. Interaction of these waves with the flat plate is investigated first. It is shown that apart from the conventional viscous boundary layer of thickness O(Re−1/2), a ‘vorticity deformation layer’ of thickness O(Re−1/4) forms along the flat-plate surface. Equations to describe the vorticity deformation process are derived, based on multiscale asymptotic techniques, and solved numerically. As a result it is shown that a strong singularity (in the form of a shock-like distribution in the wall vorticity) forms in the flow at some distance downstream of the leading edge, on the surface of the flat plate. This is likely to provoke abrupt transition in the boundary layer. With decreasing amplitude of free-stream turbulence perturbations, the singular point moves far away from the leading edge of the flat plate, and any roughness on the surface may cause Tollmien-Schlichting wave generation in the boundary layer. The theory describing the generation process is constructed on the basis of the ‘triple-deck’ concept of the boundary-layer interaction with the external inviscid flow. As a result, an explicit formula for the amplitude of Tollmien-Schlichting waves is obtained.

APA, Harvard, Vancouver, ISO, and other styles

16

Wlezien, R. W., D. E. Parekh, and T. C. Island. "Measurement of Acoustic Receptivity at Leading Edges and Porous Strips." Applied Mechanics Reviews 43, no. 5S (May 1, 1990): S167—S174. http://dx.doi.org/10.1115/1.3120797.

Full text

Abstract:

The receptivity of a laminar boundary layer to acoustic disturbances in the vicinity of a leading edge and a narrow porous surface is investigated experimentally. The relative importance of the receptivity mechanisms is explored for leading edge and porous surface configurations. Several methods to decouple the acoustic and instability wave velocity perturbations are discussed, and consistent estimates of the Tollmien-Schlichting modes are achieved when the acoustic field is directly estimated from profiles of the total fluctuating velocity. A 24:1 leading edge produces negligible Tollmien-Schlichting response when interacting with symmetric acoustic disturbances and is used to confirm the porous-surface receptivity mechanism.

APA, Harvard, Vancouver, ISO, and other styles

17

De Tullio, Nicola, and Anatoly I. Ruban. "A numerical evaluation of the asymptotic theory of receptivity for subsonic compressible boundary layers." Journal of Fluid Mechanics 771 (April 21, 2015): 520–46. http://dx.doi.org/10.1017/jfm.2015.196.

Full text

Abstract:

The capabilities of the triple-deck theory of receptivity for subsonic compressible boundary layers have been thoroughly investigated through comparisons with numerical simulations of the compressible Navier–Stokes equations. The analysis focused on the two Tollmien–Schlichting wave linear receptivity problems arising due to the interaction between a low-amplitude acoustic wave and a small isolated roughness element, and the low-amplitude time-periodic vibrations of a ribbon placed on the wall of a flat plate. A parametric study was carried out to look at the effects of roughness element and vibrating ribbon longitudinal dimensions, Reynolds number, Mach number and Tollmien–Schlichting wave frequency. The flat plate is considered isothermal, with a temperature equal to the laminar adiabatic-wall temperature. Numerical simulations of the full and the linearised compressible Navier–Stokes equations have been carried out using high-order finite differences to obtain, respectively, the steady basic flows and the unsteady disturbance fields for the different flow configurations analysed. The results show that the asymptotic theory and the Navier–Stokes simulations are in good agreement. The initial Tollmien–Schlichting wave amplitudes and, in particular, the trends indicated by the theory across the whole parameter space are in excellent agreement with the numerical results. An important finding of the present study is that the behaviour of the theoretical solutions obtained for $\mathit{Re}\rightarrow \infty$ holds at finite Reynolds numbers and the only conditions needed for the theoretical predictions to be accurate are that the receptivity process be linear and the free-stream Mach number be subsonic.

APA, Harvard, Vancouver, ISO, and other styles

18

Shen, Luyu, and Changgen Lu. "On the Generation of Instability Tollmien-Schlichting Waves by Free-Stream Turbulence." Advances in Applied Mathematics and Mechanics 9, no. 2 (January 9, 2017): 429–38. http://dx.doi.org/10.4208/aamm.2015.m998.

Full text

Abstract:

AbstractThe beginning of the transition from the laminar to a turbulent flow is usually the generation of instability Tollmien-Schlichting (T-S) waves in the boundary layer. Previously, most numerical and experimental researches focused on generating instability T-S waves through the external disturbances such as acoustic waves and vortical disturbances interacting with wall roughness or at the leading-edge of flatplate, whereas only a few paid attention to the excitation of the T-S waves directly by free-stream turbulence (FST). In this study, the generating mechanism of the temporal mode T-S waves under free-stream turbulence is investigated by using direct numerical simulation (DNS) and fast Fourier transform. Wave packets superposed by a group of stability, neutral and instability T-S waves are discovered in the boundary layer. In addition, the relation between the amplitude of the imposed free-stream turbulence and the amplitude of the excited T-S wave is also obtained.

APA, Harvard, Vancouver, ISO, and other styles

19

Albrecht, T., H. Metzkes, R. Grundmann, G. Mutschke, and G. Gerbeth. "Tollmien--Schlichting wave damping by a streamwise oscillating Lorentz force." Magnetohydrodynamics 44, no. 3 (2008): 205–22. http://dx.doi.org/10.22364/mhd.44.3.1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Singer, Bart A., and Thomas A. Zang. "Tollmien—Schlichting wave/Dean vortex interactions in curved channel flow." Journal of Fluid Mechanics 240, no. -1 (July 1992): 681. http://dx.doi.org/10.1017/s0022112092000260.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Mureithi, E. "The effect of buoyancy on upper-branch Tollmien-Schlichting wave." IMA Journal of Applied Mathematics 58, no. 1 (February 1, 1997): 19–50. http://dx.doi.org/10.1093/imamat/58.1.19.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Jiang, Xianyang. "Revisiting hot-wire anemometer measurement of Tollmien–Schlichting waves on a flat plate." International Journal of Modern Physics B 34, no. 14n16 (June 2, 2020): 2040095. http://dx.doi.org/10.1142/s0217979220400950.

Full text

Abstract:

The amplification of Tollmien–Schlichting (T-S) wave plays an important role in the process of boundary-layer transition. This paper investigates the measurement of T-S wave using hot-wire anemometer (HWA) in a wind tunnel. To precisely acquire T-S wave, the vibration of hot-wire probe and the influence of electromagnetic interference (EMI) are considered. By introducing different amplitudes and frequencies of vibration ribbon, the development of T-S waves is obtained. Lift-up of low-speed fluid and downward of high-speed fluid are observed during the transition.

APA, Harvard, Vancouver, ISO, and other styles

23

WU, XUESONG. "On local boundary-layer receptivity to vortical disturbances in the free stream." Journal of Fluid Mechanics 449 (December 10, 2001): 373–93. http://dx.doi.org/10.1017/s0022112001006401.

Full text

Abstract:

Prompted by the recent experiments of Dietz (1999) on boundary-layer receptivity due to a local roughness interacting with a vortical disturbance in the free stream, this paper undertakes to present a second-order asymptotic theory based on the tripledeck formulation. The asymptotic approach allows us to treat vortical perturbations with a fairly general vertical distribution, and confirms Dietz's conclusion that for the convecting periodic wake in his experiments, the receptivity is independent of its vertical structure and can be fully characterized by its slip velocity at the edge of the boundary layer. As in the case of distributed vortical receptivity, dominant interactions that generate Tollmien–Schlichting waves take place in the upper deck as well as in the so-called edge layer centred at the outer reach of the boundary layer. The initial amplitude of the excited Tollmien–Schlichting wave is determined to O(R−1/8) accuracy, where R is the global Reynolds number. An appropriate superposition formula is derived for the case of multiple roughness elements. A comprehensive comparison is made with Dietz's experimental data, and an excellent quantitative agreement has been found for the first time, thereby resolving some uncertainties about this receptivity mechanism.

APA, Harvard, Vancouver, ISO, and other styles

24

Ruban, A. I., T. Bernots, and M. A. Kravtsova. "Linear and nonlinear receptivity of the boundary layer in transonic flows." Journal of Fluid Mechanics 786 (November 30, 2015): 154–89. http://dx.doi.org/10.1017/jfm.2015.587.

Full text

Abstract:

In this paper we analyse the process of the generation of Tollmien–Schlichting waves in a laminar boundary layer on an aircraft wing in the transonic flow regime. We assume that the boundary layer is exposed to a weak acoustic noise. As it penetrates the boundary layer, the Stokes layer forms on the wing surface. We further assume that the boundary layer encounters a local roughness on the wing surface in the form of a gap, step or hump. The interaction of the unsteady perturbations in the Stokes layer with steady perturbations produced by the wall roughness is shown to lead to the formation of the Tollmien–Schlichting wave behind the roughness. The ability of the flow in the boundary layer to convert ‘external perturbations’ into instability modes is termed the receptivity of the boundary layer. In this paper we first develop the linear receptivity theory. Assuming the Reynolds number to be large, we use the transonic version of the viscous–inviscid interaction theory that is known to describe the stability of the boundary layer on the lower branch of the neutral curve. The linear receptivity theory holds when the acoustic noise level is weak, and the roughness height is small. In this case we were able to deduce an analytic formula for the amplitude of the generated Tollmien–Schlichting wave. In the second part of the paper we lift the restriction on the roughness height, which allows us to study the flows with local separation regions. A new ‘direct’ numerical method has been developed for this purpose. We performed the calculations for different values of the Kármán–Guderley parameter, and found that the flow separation leads to a significant enhancement of the receptivity process.

APA, Harvard, Vancouver, ISO, and other styles

25

de Paula, I. B., W. Würz, E. Krämer, V. I. Borodulin, and Y. S. Kachanov. "Weakly nonlinear stages of boundary-layer transition initiated by modulated Tollmien–Schlichting waves." Journal of Fluid Mechanics 732 (September 12, 2013): 571–615. http://dx.doi.org/10.1017/jfm.2013.420.

Full text

Abstract:

AbstractWeakly nonlinear interactions involving amplitude-modulated Tollmien–Schlichting waves in an incompressible, two-dimensional aerofoil boundary layer are investigated experimentally. Selected resonant regimes are examined with emphasis on the regimes where more than one fundamental Tollmien–Schlichting (TS) wave is present in the flow. The experiments were performed on an NLF-type aerofoil section for glider applications. Disturbances with controlled frequency-spanwise-wavenumber spectra were excited in the boundary layer and studied by phase-locked hot-wire measurements. The results show that nonlinear mechanisms connected with the steepening of the primary TS wave modulation do not play any significant role in the transition scenarios studied. It is also shown that modulations of the two-dimensional fundamental waves tend to generate additional modes at modulation frequency. These low-frequency disturbances are found to be produced by a non-resonant quadratic combination of spectral components of the primary, modulated TS wave. The investigations show that the efficiency of the process is higher for three-dimensional low-frequency modes in comparison with two-dimensional modes. Thus, the emergence of three-dimensionality for the low-frequency waves does not require any resonant interactions. In a subsequent nonlinear stage, the self-generated detuned subharmonics are found to be strongly amplified due to resonant interactions with the primary TS waves. The sequence of weakly nonlinear mechanisms found and investigated here seems to be the most likely route to the laminar–turbulent transition, at least for two-dimensional boundary layers of aerofoils with a long extent of laminar flow and in a ‘natural’ disturbance environment.

APA, Harvard, Vancouver, ISO, and other styles

26

Dempsey, L. J., K. Deguchi, P. Hall, and A. G. Walton. "Localized vortex/Tollmien–Schlichting wave interaction states in plane Poiseuille flow." Journal of Fluid Mechanics 791 (February 15, 2016): 97–121. http://dx.doi.org/10.1017/jfm.2016.50.

Full text

Abstract:

Strongly nonlinear three-dimensional interactions between a roll–streak structure and a Tollmien–Schlichting wave in plane Poiseuille flow are considered in this study. Equations governing the interaction at high Reynolds number originally derived by Bennett et al. (J. Fluid Mech., vol. 223, 1991, pp. 475–495) are solved numerically. Travelling wave states bifurcating from the lower branch linear neutral point are tracked to finite amplitudes, where they are observed to localize in the spanwise direction. The nature of the localization is analysed in detail near the relevant spanwise locations, revealing the presence of a singularity which slowly develops in the governing interaction equations as the amplitude of the motion is increased. Comparisons with the full Navier–Stokes equations demonstrate that the finite Reynolds number solutions gradually approach the numerical asymptotic solutions with increasing Reynolds number.

APA, Harvard, Vancouver, ISO, and other styles

27

Ustinov, M. V. "Interaction of a tollmien-schlichting wave with a local flow inhomogeneity." Journal of Applied Mechanics and Technical Physics 39, no. 1 (January 1998): 65–72. http://dx.doi.org/10.1007/bf02467999.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Xu, Hui, Spencer J. Sherwin, Philip Hall, and Xuesong Wu. "The behaviour of Tollmien–Schlichting waves undergoing small-scale localised distortions." Journal of Fluid Mechanics 792 (March 3, 2016): 499–525. http://dx.doi.org/10.1017/jfm.2016.93.

Full text

Abstract:

This paper is concerned with the behaviour of Tollmien–Schlichting (TS) waves experiencing small localised distortions within an incompressible boundary layer developing over a flat plate. In particular, the distortion is produced by an isolated roughness element located at $\mathit{Re}_{x_{c}}=440\,000$. We considered the amplification of an incoming TS wave governed by the two-dimensional linearised Navier–Stokes equations, where the base flow is obtained from the two-dimensional nonlinear Navier–Stokes equations. We compare these solutions with asymptotic analyses which assume a linearised triple-deck theory for the base flow and determine the validity of this theory in terms of the height of the small-scale humps/indentations taken into account. The height of the humps/indentations is denoted by $h$, which is considered to be less than or equal to $x_{c}\mathit{Re}_{x_{c}}^{-5/8}$ (corresponding to $h/{\it\delta}_{99}<6\,\%$ for our choice of $\mathit{Re}_{x_{c}}$). The rescaled width $\hat{d}~(\equiv d/(x_{c}\mathit{Re}_{x_{c}}^{-3/8}))$ of the distortion is of order $\mathit{O}(1)$ and the width $d$ is shorter than the TS wavelength (${\it\lambda}_{TS}=11.3{\it\delta}_{99}$). We observe that, for distortions which are smaller than 0.1 of the inner deck height ($h/{\it\delta}_{99}<0.4\,\%$), the numerical simulations confirm the asymptotic theory in the vicinity of the distortion. For larger distortions which are still within the inner deck ($0.4\,\%<h/{\it\delta}_{99}<5.5\,\%$) and where the flow is still attached, the numerical solutions show that both humps and indentations are destabilising and deviate from the linear theory even in the vicinity of the distortion. We numerically determine the transmission coefficient which provides the relative amplification of the TS wave over the distortion as compared to the flat plate. We observe that for small distortions, $h/{\it\delta}_{99}<5.5\,\%$, where the width of the distortion is of the order of the boundary layer, a maximum amplification of only 2 % is achieved. This amplification can however be increased as the width of the distortion is increased or if multiple distortions are present. Increasing the height of the distortion so that the flow separates ($7.2\,\%<h/{\it\delta}_{99}<12.8\,\%$) leads to a substantial increase in the transmission coefficient of the hump up to 350 %.

APA, Harvard, Vancouver, ISO, and other styles

29

Katsis, C., and T. R. Akylas. "Wind-Generated Surface Waves on a Viscous Fluid." Journal of Applied Mechanics 52, no. 1 (March 1, 1985): 208–12. http://dx.doi.org/10.1115/1.3168999.

Full text

Abstract:

The excitation of surface waves on a viscous fluid by shear flows is studied. Turbulent and laminar air flows over oil of low and high viscosity are considered. It is found that the dominant wave-generation mechanism depends crucially on the shear-flow profile: for a turbulent flow, long surface waves are generated at low wind speeds due to the work done by the stress components in phase with the surface slope, while Kelvin-Helmholtz instability is responsible for the excitation of short waves at higher wind speeds. On the other hand, for a laminar shear flow, direct resonance between surface waves and Tollmien-Schlichting waves in the shear flow is the dominant wave-generation mechanism.

APA, Harvard, Vancouver, ISO, and other styles

30

Dörr, Philipp C., and Markus J. Kloker. "Numerical Investigations on Tollmien–Schlichting Wave Attenuation Using Plasma-Actuator Vortex Generators." AIAA Journal 56, no. 4 (April 2018): 1305–9. http://dx.doi.org/10.2514/1.j056779.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Dempsey, Liam J., and Andrew G. Walton. "Vortex/Tollmien–Schlichting wave interaction states in the asymptotic suction boundary layer." Quarterly Journal of Mechanics and Applied Mathematics 70, no. 3 (May 25, 2017): 187–213. http://dx.doi.org/10.1093/qjmam/hbx004.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

WALTON, ANDREW G., and RUPA A. PATEL. "Singularity formation in the strongly nonlinear wide-vortex/Tollmien–Schlichting-wave interaction equations." Journal of Fluid Mechanics 400 (December 10, 1999): 265–93. http://dx.doi.org/10.1017/s0022112099006503.

Full text

Abstract:

A combined numerical/analytical study of the wide-vortex/wave interaction equations, describing boundary-layer instability, is presented. Depending on the obliqueness β of the wave input, different solution properties are obtained. For β = 1, oscillations in the wave amplitude lead to the evolution of a strongly three-dimensional mean flow, while for β = 2 the interaction is characterized by the development of a singularity in the wave pressure amplitude. This latter behaviour is modelled using an approximate form for the mean flow skin friction and the resulting amplitude equation is analysed using a combination of numerical and asymptotic techniques. A simple method is described for determining the singularity location for a given spanwise wavenumber, and the asymptotic behaviour of the pressure amplitude as the singularity is approached is deduced.

APA, Harvard, Vancouver, ISO, and other styles

33

Henningson, Dan S., and P. Henrik Alfredsson. "The wave structure of turbulent spots in plane Poiseuille flow." Journal of Fluid Mechanics 178 (May 1987): 405–21. http://dx.doi.org/10.1017/s0022112087001289.

Full text

Abstract:

The wave packets located at the wingtips of turbulent spots in plane Poiseuille flow have been investigated by hot-film anemometry. The streamwise velocity disturbances associated with the waves were found to be antisymmetric with respect to the channel centreline. The amplitude of the waves had a maximum close to the wall that was about 4% of the centreline velocity. The modified velocity field outside the spot was measured and linear stability analysis of the measured velocity profiles showed that the flow field was less stable than the undisturbed flow. The phase velocity and amplitude distribution of the waves were in reasonable agreement with the theory, which together with the symmetry properties indicate that the wave packet consisted of the locally least stable Tollmien-Schlichting mode.

APA, Harvard, Vancouver, ISO, and other styles

34

Savaş, Ö. "On flow visualization using reflective flakes." Journal of Fluid Mechanics 152 (March 1985): 235–48. http://dx.doi.org/10.1017/s0022112085000672.

Full text

Abstract:

An analysis of flow visualization using small reflective flakes is introduced. This rational analysis is based on a stochastic treatment of Jeffery's (1922) solution for the motion of ellipsoidal particles in a viscous fluid, wherein thin flakes tend to align with stream surfaces. The predicted light fields are confirmed by examples of parallel flows, the flow over a rotating disk, and the spinup from rest in a cylindrical cavity. The Tollmien–Schlichting wave packet trailing a turbulent spot is taken as an example to discuss the suitability of the technique for visualizing small-amplitude waves. Attenuation of light through a suspension is described.

APA, Harvard, Vancouver, ISO, and other styles

35

Petrov, G. V. "Effect of the Tollmien — Schlichting wave on averaged parameters of the boundary layer." Thermophysics and Aeromechanics 17, no. 4 (December 2010): 483–88. http://dx.doi.org/10.1134/s0869864310040025.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Ustinov, M. V. "Secondary instability modes generated by a Tollmien-Schlichting wave scattering from a bump." Theoretical and Computational Fluid Dynamics 7, no. 5 (September 1995): 341–54. http://dx.doi.org/10.1007/bf00312413.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Makomaski, A. H. "Numerical Simulation of Oscillations in a Continuous Optical Discharge." Transactions of the Canadian Society for Mechanical Engineering 11, no. 4 (December 1987): 201–14. http://dx.doi.org/10.1139/tcsme-1987-0023.

Full text

Abstract:

A numerical method based on the assumptions of Forester and Emery is used to study the oscillatory behaviour of the plume and of the thermal wave associated with a point plasma, sustained by continuous optical discharge of a c.w. laser. Computations are carried out to simulate conditions in argon at 4 atm and initially at room temperature. The numerical results explain or confirm many experimental features and generally quantitative agreement with experiment is good. Application of Kimura’s stability theory to the plume suggests aerodynamic instability as the origin of the oscillations. As for flames, these oscillations are associated with waves analogous to the Tollmien-Schlichting waves in laminar boundary layers.

APA, Harvard, Vancouver, ISO, and other styles

38

Yeo, K. S. "The three-dimensional stability of boundary-layer flow over compliant walls." Journal of Fluid Mechanics 238 (May 1992): 537–77. http://dx.doi.org/10.1017/s0022112092001812.

Full text

Abstract:

This paper examines the linear stability of the Blasius boundary layer over compliant walls to three-dimensional (oblique) disturbance wave modes. The formulation of the eigenvalue problem is applicable to compliant walls possessing general material anisotropy. Isotropic-material walls and selected classes of anisotropic-material walls are studied. When the properties of the wall are identical with respect to all oblique wave directions, the stability eigenvalue problem for unstable three-dimensional wave modes may be reduced to an equivalent problem for two-dimensional modes. The results for isotropic-material walls show that three-dimensional Tollmien–Schlichting instability modes are more dominant than their two-dimensional counterparts when the walls are sufficiently compliant. The critical Reynolds number for Tollmien-Schlichting instability may be given by three-dimensional modes. Furthermore, for highly compliant walls, calculations based solely on two-dimensional modes are likely to underestimate the maximum disturbance growth factor needed for transition prediction and correlation. However, because the disturbance growth rates on highly compliant walls are much lower than those on a rigid wall, significant delay of transition may still be possible provided compliance-induced instabilities are properly suppressed. Walls featuring material anisotropy which have reduced stiffness to shear deformation in the transverse and oblique planes are also investigated. Such anisotropy is found to be effective in reducing the growth rates of the three-dimensional modes relative to those of the two-dimensional modes.

APA, Harvard, Vancouver, ISO, and other styles

39

Greiner, M., R. F. Chen, and R. A. Wirtz. "Heat Transfer Augmentation Through Wall-Shape-Induced Flow Destabilization." Journal of Heat Transfer 112, no. 2 (May 1, 1990): 336–41. http://dx.doi.org/10.1115/1.2910382.

Full text

Abstract:

Experiments on heat transfer augmentation in a rectangular cross-section water channel are reported. The channel geometry is designed to excite normally damped Tollmien-Schlichting modes in order to enhance mixing. In this experiment, a hydrodynamically fully developed flow encounters a test section where one channel boundary is a series of periodic, saw-tooth, transverse grooves. Free shear layers span the groove openings, separating the main channel flow from the recirculating vortices contained within each cavity. The periodicity length of the grooves is equal to one-half of the expected wavelength of the most unstable mode. The remaining channel walls are flat, and the channel has an aspect ratio of 10:1. Experiments are performed over the Reynolds number range of 300 to 15,000. Streakline flow visualization shows that the flow is steady at the entrance, but becomes oscillatory downstream of an onset location. This location moves upstream with increasing Reynolds numbers. Initially formed traveling waves are two dimensional with a wavelength equal to the predicted most unstable Tollmien-Schlichting mode. Waves become three dimensional with increasing Reynolds number and distance from onset. Some evidence of wave motion persists into the turbulent flow regime. Heat transfer measurements along the smooth channel boundary opposite the grooved wall show augmentation (65 percent) over the equivalent flat channel in the Reynolds number range 1200 to 4800. The degree of enhancement obtained is shown to depend on the channel Reynolds number, and increases with the distance from the onset location.

APA, Harvard, Vancouver, ISO, and other styles

40

FASEL, HERMANN F. "Numerical investigation of the interaction of the Klebanoff-mode with a Tollmien–Schlichting wave." Journal of Fluid Mechanics 450 (January 9, 2002): 1–33. http://dx.doi.org/10.1017/s0022112002006140.

Full text

Abstract:

Direct numerical simulations (DNS) of the Navier–Stokes equations are used to investigate the role of the Klebanoff-mode in laminar–turbulent transition in a flatplate boundary layer. To model the effects of free-stream turbulence, volume forces are used to generate low-frequency streamwise vortices outside the boundary layer. A suction/blowing slot at the wall is used to generate a two-dimensional Tollmien–Schlichting (TS) wave inside the boundary layer. The characteristics of the fluctuations inside the boundary layer agree very well with those measured in experiments. It is shown how the interaction of the Klebanoff-mode with the two-dimensional TS-wave leads to the formation of three-dimensional TS-wavepackets. When the disturbance amplitudes reach a critical level, a fundamental resonance-type secondary instability causes the breakdown of the TS-wavepackets into turbulent spots.

APA, Harvard, Vancouver, ISO, and other styles

41

Wu, Xuesong, Philip A. Stewart, and Stephen J. Cowley. "On the weakly nonlinear development of Tollmien-Schlichting wavetrains in boundary layers." Journal of Fluid Mechanics 323 (September 25, 1996): 133–71. http://dx.doi.org/10.1017/s0022112096000870.

Full text

Abstract:

The nonlinear development of a weakly modulated Tollmien-Schlichting wavetrain in a boundary layer is studied theoretically using high-Reynolds-number asymptotic methods. The ‘carrier’ wave is taken to be two-dimensional, and the envelope is assumed to be a slowly varying function of time and of the streamwise and spanwise variables. Attention is focused on the scalings appropriate to the so-called ‘upper branch’ and ‘high-frequency lower branch’. The dominant nonlinear effects are found to arise in the critical layer and the surrounding ‘diffusion layer’: nonlinear interactions in these regions can influence the development of the wavetrain by producing a spanwise-dependent mean-flow distortion. The amplitude evolution is governed by an integro-partial-differential equation, whose nonlinear term is history-dependent and involves the highest derivative with respect to the spanwise variable. Numerical solutions show that a localized singularity can develop at a finite distance downstream. This singularity seems consistent with the experimentally observed focusing of vorticity at certain spanwise locations, although quantitative comparisons have not been attempted.

APA, Harvard, Vancouver, ISO, and other styles

42

Sundaram, Prasannabalaji, Tapan K. Sengupta, and Soumyo Sengupta. "Is Tollmien-Schlichting wave necessary for transition of zero pressure gradient boundary layer flow?" Physics of Fluids 31, no. 3 (March 2019): 031701. http://dx.doi.org/10.1063/1.5089294.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

de Paula, I. B., W. Wurz, and M. A. F. Medeiros. "Experimental study of a Tollmien–Schlichting wave interacting with a shallow 3D roughness element." Journal of Turbulence 9 (January 2008): N7. http://dx.doi.org/10.1080/14685240701790706.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Manuilovich, S. V. "Propagation of a Tollmien-Schlichting wave over the junction between rigid and compliant surfaces." Fluid Dynamics 39, no. 5 (September 2004): 702–17. http://dx.doi.org/10.1007/s10697-005-0004-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Goldstein, M. E. "Scattering of acoustic waves into Tollmien-Schlichting waves by small streamwise variations in surface geometry." Journal of Fluid Mechanics 154 (May 1985): 509–29. http://dx.doi.org/10.1017/s0022112085001641.

Full text

Abstract:

By using the triple-deck scaling of Stewartson (1969) and Messiter (1970) we show that small but relatively sudden surface geometry variations that produce only very weak static pressure variations can nevertheless produce strong, i.e. 0(1), coupling between an externally imposed acoustic disturbance and a spatially growing Tollmien- Schlichting wave. The analysis provides a qualitative explanation of the Leehey & Shapiro (1979) boundary-layer receptivity measurements and is in good quantitative agreement with the Aizin & Polyakov (1979) experiment. It may also explain why small ‘trip wires’ can promote early transition.

APA, Harvard, Vancouver, ISO, and other styles

46

QIU, JINHAO, and TAKAHIRO OKA. "ACTIVE CONTROL OF BOUNDARY LAYER USING A NEURAL NETWORK AND A FLAPPING ACTUATOR." Modern Physics Letters B 19, no. 28n29 (December 20, 2005): 1587–90. http://dx.doi.org/10.1142/s0217984905009973.

Full text

Abstract:

This study deals with the active control of T-S (Tollmien-Schlichting) wave in a two-dimensional boundary layer over a flat plate using a neural network and a flapping actuator. The flapping actuator consists of a thin aluminum plate and a piezoelectric element bonded together. Microphones were used as sensors to measure the pressure fluctuation in the boundary layer. A neural network was used to control the piezoelectric actuator based on the pressure signals from the sensors. The experimental results shows that the T-S wave in the boundary layer can be successfully suppressed even when its phase, amplitude and frequency change with time.

APA, Harvard, Vancouver, ISO, and other styles

47

Raposo, Henrique, Shahid Mughal, and Richard Ashworth. "An adjoint compressible linearised Navier–Stokes approach to model generation of Tollmien–Schlichting waves by sound." Journal of Fluid Mechanics 877 (August 19, 2019): 105–29. http://dx.doi.org/10.1017/jfm.2019.601.

Full text

Abstract:

The generation of the first-mode instability through scattering of an acoustic wave by localised surface roughness, suction or heating is studied with a time-harmonic compressible adjoint linearised Navier–Stokes (AHLNS) approach for subsonic flow conditions. High Strouhal number analytical solutions to the compressible Stokes layer problem are deduced and shown to be in better agreement with numerical solutions compared to previous works. The adjoint methodology of Hill in the context of acoustic receptivity is extended to the compressible flow regime and an alternative formulation to predict sensitivity to the angle of incidence of an acoustic wave is proposed. Good agreement of the acoustic AHLNS receptivity model is found with published direct numerical simulations and the simpler finite Reynolds number approach. Parametric investigations of the influence of the acoustic wave angle on receptivity amplitudes reveal that the linearised unsteady boundary layer equations are a valid model of the acoustic signature for a large range of acoustic wave obliqueness values, failing only where the wave is highly oblique and travels upstream. An extensive parametric study of the influence of frequency, spanwise wavenumber, local Reynolds number and free-stream Mach number over the efficiency function for the different types of wall perturbation mechanisms is undertaken.

APA, Harvard, Vancouver, ISO, and other styles

48

MASLOV, A. A., A. N. SHIPLYUK, A. A. SIDORENKO, and D. ARNAL. "Leading-edge receptivity of a hypersonic boundary layer on a flat plate." Journal of Fluid Mechanics 426 (January 10, 2001): 73–94. http://dx.doi.org/10.1017/s0022112000002147.

Full text

Abstract:

Experimental investigations of the boundary layer receptivity, on the sharp leading edge of a at plate, to acoustic waves induced by two-dimensional and three- dimensional perturbers, have been performed for a free-stream Mach number M∞ = 5.92. The fields of controlled free-stream disturbances were studied. It was shown that two-dimensional and three-dimensional perturbers radiate acoustic waves and that these perturbers present a set of harmonic motionless sources and moving sources with constant amplitude. The disturbances excited in the boundary layer were measured. It was found that acoustic waves impinging on the leading edge generate Tollmien–Schlichting waves in the boundary layer. The receptivity coefficients were obtained for several radiation conditions and intensities. It was shown that there is a dependence of receptivity coefficients on the wave inclination angles.

APA, Harvard, Vancouver, ISO, and other styles

49

Mendonça, Márcio T., Laura L. Pauley, and Philip J. Morris. "Effect of wave frequency on the nonlinear interaction between Görtler vortices and three-dimensional Tollmien-Schlichting waves." Journal of the Brazilian Society of Mechanical Sciences 22, no. 1 (2000): 69–82. http://dx.doi.org/10.1590/s0100-73862000000100006.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Hughes, J. D., and G. J. Walker. "Natural Transition Phenomena on an Axial Compressor Blade." Journal of Turbomachinery 123, no. 2 (February 1, 2000): 392–401. http://dx.doi.org/10.1115/1.1351816.

Full text

Abstract:

Data from a surface hot-film array on the outlet stator of a 1.5-stage axial compressor are analyzed to look for direct evidence of natural transition phenomena. An algorithm is developed to identify instability waves within the Tollmien–Schlichting (T–S) frequency range. The algorithm is combined with a turbulent intermittency detection routine to produce space-time diagrams showing the probability of instability wave occurrence prior to regions of turbulent flow. The paper compares these plots for a range of blade loading, with free-stream conditions corresponding to the maximum and minimum inflow disturbance periodicity produced by inlet guide vane clocking. Extensive regions of amplifying instability waves are identified in nearly all cases. The implications for transition prediction in decelerating flow regions on axial turbomachine blades are discussed.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Tollmien-Schlichting wave'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles