Asymptotic theory of nonstationary separation

Sychev, V. V.

doi:10.1007/bf01051983

Cited by 12 publications

(10 citation statements)

References 11 publications

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“…This procedure is similar to the one followed by Van Dommelen & Shen (1982) for two-dimensional separation. In contrast to the steady viscous singularities of Goldstein (1948) and Brown (1965), and the ideas of Sears & Telionis (1975), the unsteady singularity is essentially inviscid in character and consists of two vortex sheets separated by an increasingly large central inviscid region (as found by Ockendon (1972) for a rotating disc with suction, and by Sychev (1979Sychev ( , 1980, Van Dommelen & Shen (19801,1983a,b), Williams & Stewartson (1983) Shen (1982), the closing remarks of subsection 4c, and part 2), that the leading order coefficients in the Taylor series expansion near the stationary point are non-zero.…”

Section: Y U = D D Y W = Omentioning

confidence: 99%

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On the Lagrangian description of unsteady boundary-layer separation. Part 1. General theory

Dommelen

Cowley

1990

J. Fluid Mech.

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Asymptotic structhres for a number of unsteady three-dimensional separating flows follow and depend on the symmetry properties of the flow (e.g. line symmetry, axial symmetry).In the absence of any symmetry, the singularity structure just prior to separation is found to be quasi two-dimensional with a displacement thickness in the form of a crescent shaped ridge. Physically the singularities can be understood in terms of the behavior of a fluid element inside the boundary layer which contracts in a direction parallel to the boundary and expands normal to it, thus forcing the fluid above it to be ejected from the boundary layer.'Work funded under Space Act Agreement C99066G; presently at

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Section: Y U = D D Y W = Omentioning

confidence: 99%

“…While this three-dimensional form of the MRS condition seems new, the general applicability of the two-dimensional case is fairly well established both theoretically (Moore 1958, Sears Rt Telionis 1975, Williams 1977, Shen 1978, Sychev 1979len Rt Shen 1980b, 1983a,b, Van Dommelen 1981 and experimentally (Ludwig 1964, Didden & Ho 1985.…”

Section: Y U = D D Y W = Omentioning

confidence: 99%

On the Lagrangian description of unsteady boundary-layer separation. Part 1. General theory

Dommelen

Cowley

1990

J. Fluid Mech.

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“…Sychev (1978) was the first to formulate this problem in the course of his analysis of viscous wake breakdown in incompressible fluid flow. It was then shown to play a central role in describing the incompressible boundary-layer separation on a downstream moving wall (see Sychev 1979Sychev , 1984. Later, Battam et al (2004) demonstrated that this problem also describes the formation of the flow reversal in the viscous wake interacting with a shock wave in supersonic gas flows.…”

Section: Viscous Region Vmentioning

confidence: 97%

“…An important step forward was made by Sychev (1979), who applied the ideas of triple-deck theory to the analysis of steady boundary-layer separation on a downstream moving wall. He confirmed, first of all, that the solution of the classical boundary-layer equations indeed develops a singularity at the Moore-Rott-Sears point (Sychev 1980).…”

mentioning

confidence: 99%

“…A new theory was developed by Sychev (1979Sychev ( , 1984Sychev ( , 1987 with help from van Dommelen & Shen (1983) based on the asymptotic analysis of the Navier-Stokes equations at large values of the Reynolds number. It was shown that, similar to the case of motionless wall (see Sychev 1972), a key element of the separation process is mutual interaction of the boundary layer and external inviscid part of the flow.…”

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On unsteady boundary-layer separation in supersonic flow. Part 1. Upstream moving separation point

et al. 2011

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This study is concerned with the boundary-layer separation from a rigid body surface in unsteady two-dimensional laminar supersonic flow. The separation is assumed to be provoked by a shock wave impinging upon the boundary layer at a point that moves with speed V sh along the body surface. The strength of the shock and its speed V sh are allowed to vary with time t, but not too fast, namely, we assume that the characteristic time scale t Re −1/2 /V 2 w . Here Re denotes the Reynolds number, and V w = −V sh is wall velocity referred to the gas velocity V ∞ in the free stream. We show that under this assumption the flow in the region of interaction between the shock and boundary layer may be treated as quasi-steady if it is considered in the coordinate frame moving with the shock. We start with the flow regime when V w = O(Re −1/8 ). In this case, the interaction between the shock and boundary layer is described by classical triple-deck theory. The main modification to the usual triple-deck formulation is that in the moving frame the body surface is no longer stationary; it moves with the speed V w = −V sh . The corresponding solutions of the triple-deck equations have been constructed numerically. For this purpose, we use a numerical technique based on finite differencing along the streamwise direction and Chebyshev collocation in the direction normal to the body surface. In the second part of the paper, we assume that 1 V w O(Re −1/8 ), and concentrate our attention on the self-induced separation of the boundary layer. Assuming, as before, that the Reynolds number, Re, is large, the method of matched asymptotic expansions is used to construct the corresponding solutions of the Navier-Stokes equations in a vicinity of the separation point.

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Boundary layer separation singularities for an upstream moving wall

Dommelen

Shen

1983

Acta Mechanica

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Asymptotic theory of nonstationary separation

Cited by 12 publications

References 11 publications

On the Lagrangian description of unsteady boundary-layer separation. Part 1. General theory

On the Lagrangian description of unsteady boundary-layer separation. Part 1. General theory

On unsteady boundary-layer separation in supersonic flow. Part 1. Upstream moving separation point

Boundary layer separation singularities for an upstream moving wall

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