Stability of Boundary Layers and of Flow in Entrance Section of a Channel

HAHNEMANN, ELIZABETH; Freeman, J.; Finston, Morton

doi:10.2514/8.11627

Cited by 11 publications

(2 citation statements)

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“…Linear classical stability analysis of the channel-entrance flow has been investigated by employing the parallel-flow assumption (Hahneman, Freeman & Finston 1948;Chen & Sparrow 1967;Gupta & Garg 1981a,b), by including the non-parallel-flow effects (Garg & Gupta 1981a,b) and by using the triple-deck formalism (Smith & Bodonyi 1980). To the best of our knowledge, no experimental works exist to confirm these theoretical and numerical results.…”

Section: Channel-entrance Flowsmentioning

confidence: 99%

Entrainment and growth of vortical disturbances in the channel-entrance region

Riccó

Alvarenga

2021

J. Fluid Mech.

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The entrainment of free-stream unsteady three-dimensional vortical disturbances in the entry region of a channel is studied via matched asymptotic expansions and by numerical means. The interest is in flows at Reynolds numbers where experimental studies have documented the occurrence of intense transient growth, despite the flow being stable according to classical stability analysis. The analytical description of the vortical perturbations at the channel mouth reveals how the oncoming disturbances penetrate into the wall-attached shear layers and amplify downstream. The effects of the channel confinement, the streamwise pressure gradient and the viscous/inviscid interplay between the oncoming disturbances and the boundary-layer perturbations are discussed. The composite perturbation velocity profiles are employed as initial conditions for the unsteady boundary-region perturbation equations. At a short distance from the channel mouth, the disturbance flow is mostly confined within the shear layers and assumes the form of streamwise-elongated streaks, while farther downstream the viscous disturbances permeate the whole channel although the base flow is still mostly inviscid in the core. Symmetrical disturbances exhibit a more significant growth than anti-symmetrical disturbances, the latter maintaining a nearly constant amplitude for several channel heights downstream before growing transiently, a unique feature not reported in open boundary layers. The disturbances are more intense as the frequency decreases or the bulk Reynolds number increases. We compute the spanwise wavelengths that cause the most intense downstream growth and the threshold wall-normal wavelengths below which the perturbations are damped through viscous dissipation.

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Section: Channel-entrance Flowsmentioning

confidence: 99%

Entrainment and growth of vortical disturbances in the channel-entrance region

Riccó

Alvarenga

2021

J. Fluid Mech.

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“…It therefore appears in textbooks, and is continually re-examined as new phenomena are introduced. Thus it has been extended to axisymmetric flow (Atkinson & Goldstein 1938), tested for stability (Hahneman, Freeman & Finston 1948), modified €or magnetohydrodynamics (Shercliff 1956), for a non-Newtonian liquid (Collins & Schowalter 1963), for suction or injection through porous walls (Horton & Yuan 1964), for a viscoelastic fluid (Metzner & White 1965), for a compressible fluid (Blankenship & Chung 1967), and for a tube of general cross-section (McComas 1967).…”

Section: Introductionmentioning

confidence: 99%

Entry flow in a channel

Dyke

1970

J. Fluid Mech.

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A uniformly valid asymptotic solution for large Reynolds number is constructed for plane steady laminar flow of a liquid into the channel between two semi-infinite parallel plates. The entry condition is taken as either that for a cascade of plates in a uniform oncoming stream, or uniform flow directly at the inlet. A paradox in the standard solution of Schlichting—that near the inlet the flow due to displacement would not be the accelerated uniform core on which his expansion is based—is resolved by showing that his series for small as well as large distance actually applies only to conditions far downstream, and matches with another expansion valid near the inlet. Good agreement is found with three independent numerical solutions of the full Navier-Stokes equations, except for a discrepancy in one solution for uniform entry that is traced to erroneous neglect of inlet vorticity.

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A neglected effect in entrance flow analyses

Dealy

1965

AIChE Journal

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Stability of Boundary Layers and of Flow in Entrance Section of a Channel

Cited by 11 publications

References 0 publications

Entrainment and growth of vortical disturbances in the channel-entrance region

Entrainment and growth of vortical disturbances in the channel-entrance region

Entry flow in a channel

A neglected effect in entrance flow analyses

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