Transition Process of a Wave Train in a Laminar Boundary Layer

Wiegand, Th; Bestek, H.; Wagner, Siegfried

doi:10.1007/978-3-322-86573-1_50

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…Due to the fact that turbulent boundary layers produce higher drag than laminar layers, the delay of transition is of particular interest. Several strategies to stabilize laminar flow have been investigated extensively, such as suction, mean flow distortion and wave cancellation by superposition [2,3].…”

Section: Introductionmentioning

confidence: 99%

Study of the Effect of Parietal Suction and Blowing on the Stability of Laminar External Flow

Laouer¹,

Mezaache²,

Laouar³

2016

IJHT

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Stability and transition problems of two dimensional laminar external flow over a flat plate with wall suction and blowing are studied numerically using the temporal linear stability theory. The flow is assumed similar two-dimensional laminar boundary-layer. The mean velocity profiles are obtained numerically for the case of suction or blowing. The stability equation is given in a general form which can be applied to Chebyshev domain and in boundary layer domain and solved numerically by the Chebyshev collocation spectral method. The neutral stability curves and the critical Reynolds numbers are presented.

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Section: Introductionmentioning

confidence: 99%

Study of the Effect of Parietal Suction and Blowing on the Stability of Laminar External Flow

Laouer¹,

Mezaache²,

Laouar³

2016

IJHT

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show abstract

“…The delay of transition has a particular interest to stabilise laminar flows, where this idea has been investigated extensively. There is a number of interesting examples that include: suction, mean flow distortion, surface roughness and wave cancellation by superposition (see [2][3][4][5] ). These investigations could be intelligent strategies in most technological applications to delay the laminar-turbulent transition process in mechanism of fluid flow.…”

Section: Introductionmentioning

confidence: 99%

Competing roughness effects on the non-stationary crossflow instability of the boundary-layer over a rotating broad cone

2022

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There are two primary aims of this paper: The first aim is to investigate the effects of the roughness types of the Miklavcic and Wang (MW) model on stationary disturbances of the boundary-layer flow over a broad cone . The second aim is to examine similar effects of surface roughness, but on non-stationary modes. This study begins with the formulations of the mean-flow system based on the cone geometry. These equations are solved using a spectral numerical method based on Chebyshev polynomials, and then used to formulate the linear stability system, which are computed for obtaining neutral curves of the unsteady flows. For the stationary modes, our results indicate that the inviscid instability is more stable while the viscous instability (type II mode) entirely eliminates, as concentric grooves or isotropic roughness and the cone half-angle increases. In contrast, streamwise grooves have a slight stabilizing effect on the type I mode and a significant destabilizing effect on the viscous instability. Another finding indicates that decreasing the half-angle leads to a greater stabilizing effect of isotropic roughness on the type I modes. Our outcomes are also confirmed by the growth rate and the energy analysis, which shows a large reduction of the total energy balance as a result of increasing concentric grooves or isotropic roughness for the crossflow mode. For non-stationary modes, similar effects are observed in that increasing all levels of roughness stabilizes the type I branch (with concentric grooves and isotropic roughness having a much stronger effect than streamwise grooves).

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“…There is no doubt that this interest is due to the significant problems in fluid flow mechanics wherein most technological applications, skin-friction drag has become a greater issue in the transition to turbulence, and the delay of transition is of particular interest. Therefore the stabilization of laminar flows have been investigated extensively, interesting examples include roughness levels, suction, mean flow distortion and wave cancellation by superposition [3][4][5], as intelligent strategies to delay the laminar-turbulent transition process of flow.…”

Section: Introductionmentioning

confidence: 99%

Effects of parietal suction and injection on the stability of the Blasius boundary-layer flow over a permeable, heated plate

et al. 2021

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The main concern of this paper is to investigate the effects on the stability behavior of wall suction or injection for external boundary-layer flow over a heated, porous plate for a fluid with temperature-dependent viscosity. The wall suction or injection are applied to the flow by a simple modification for the no-penetration condition and the current boundary conditions on the flat plate. Liquid-type viscosities are found to entrain both the velocity and temperature profiles closer to the plate with increasing both temperature sensitivity and suction intensity, whereas gas-type viscosities are found to exhibit the reverse effect with increasing flow injection and decreasing temperature dependence. We present then the linear stability analysis and find that increasing both the temperature dependence (from gas-to liquid-type behavior) and suction intensity of the fluid leads to increasing critical Reynolds number to a point of maximum stability. We note also that increasing both the Prandtl number (Pr) and flow suction in the liquid-type behavior results in an increased critical Reynolds number. The magnitudes of the perturbation eigenfunctions are considered before utilising them to obtain solutions to an energy balance integral. We find that the eigenfunction profiles are imitative of the narrowing of their mean flow counterparts when increasing either the temperature dependence or the flow suction. Our results are then confirmed by the energy analysis, where we find a significant reduction in the energy produced by the disturbance with increasing suction intensity and ultimately leads to a more stable flow. Overall, there is a strong destabilizing effect with increasing injection and the temperature-dependent viscosity over a heated plate. In summary, the findings indicate that increasing the wall suction and temperature dependence results in significantly more stable flows. It is worth noting that application and extension of this study are considered in the context of chemical vapor deposition reactors.

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Transition Process of a Wave Train in a Laminar Boundary Layer

Cited by 5 publications

References 3 publications

Study of the Effect of Parietal Suction and Blowing on the Stability of Laminar External Flow

Study of the Effect of Parietal Suction and Blowing on the Stability of Laminar External Flow

Competing roughness effects on the non-stationary crossflow instability of the boundary-layer over a rotating broad cone

Effects of parietal suction and injection on the stability of the Blasius boundary-layer flow over a permeable, heated plate

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