Unsteady free surface wave-induced separation: Vortical structures and instabilities

Kandasamy, Manivannan; Xing, Tao; Stern, Frederick

doi:10.1016/j.jfluidstructs.2008.05.002

Cited by 21 publications

(12 citation statements)

References 37 publications

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“…The owl-face has been observed when a cylindrical post is mounted perpendicular to a wall (Akilli & Rockwell 2002;Palau-Salvador et al 2010), on the downstream side of a missile-shaped body at an angle of attack (Perry & Chong 1987) and on an aircraft wing (Kandasamy, Xing & Stern 2009). The leading edge of the owl-face in figure 4(a) is similar to the pattern in figure 3(a) in that it contains a saddle point (S) and the upstream streamlines diverge.…”

Section: Brief Review Of Critical Point Theorymentioning

confidence: 99%

Shock wave–boundary layer interactions in rectangular inlets: three-dimensional separation topology and critical points

Eagle

Driscoll

2014

J. Fluid Mech.

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The interaction between two separated flow regions was studied for the fundamental problem of a shock wave-boundary layer interaction (SBLI) within a rectangular inlet. One motivation is that the inlet of an engine on a supersonic aircraft may contain separation zones on the sidewalls and the bottom wall; if one region separates first it can alter the flow on the other wall and lead to engine unstart. In our work an oblique shock wave was generated by a wedge suspended from the upper wall of a Mach 2.75 wind tunnel. Stereo particle image velocimetry (PIV) measurements were recorded in 25 planes that include all three possible orthogonal orientations. The lateral velocity and vorticity measurements help to explain the underlying flow structure and these quantities were not measured previously for this problem. It is concluded that the sidewall and bottom wall separation zones interact due to an underlying flow structure that is similar to the two types of 3-D separation patterns previously described by Tobak & Peake (Annu. Rev. Fluid Mech., vol. 14, 1982, pp. 61-85). Separation first occurs at an upstream location where the shock interacts with the sidewall. Lateral velocities direct flow toward the centreline to cause separation on the bottom wall. This causes significant curvature of the shock wave, so that even the region near the tunnel centreline cannot be explained by conventional 2-D concepts. A number of critical points (saddle points, nodes, focus points) were identified. Results are consistent with the general ideas of Burton & Babinsky (J. Fluid Mech., vol. 707, 2012, pp. 287-306) and help to provide details of how the sidewalls redistribute the adverse pressure gradient in space.

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Section: Brief Review Of Critical Point Theorymentioning

confidence: 99%

Shock wave–boundary layer interactions in rectangular inlets: three-dimensional separation topology and critical points

Eagle

Driscoll

2014

J. Fluid Mech.

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“…16 shows the separation pattern of the mean flow. The separated shear layer was visualized approximately using the isosurfaces of the stagnation C p near the interface immediately before the separation, assuming that the flow outside the separation region is inviscid (Kandasamy et al, 2009). Inside the separated region, the mean vortex core lines are extracted using the vortex core identification technique (Sujudi and Haimes, 1995).…”

Section: Boundary Layermentioning

confidence: 99%

“…Its far-wake velocity magnitude is also remarkably smaller than the deep flow region. In addition, the small positive streamwise centerline velocity zone is observed to exist immediately downstream of the cylinder (see the top-left close-up view of the interface centerline velocity), which means a complicated interface topology with the presence of nodal and saddle points (Kandasamy et al, 2009). The mean streamwise velocities in the wake for several vertical locations and the interface are compared in Fig.…”

Section: Boundary Layermentioning

confidence: 99%

The effect of air–water interface on the vortex shedding from a vertical circular cylinder

Suh

Yang

Stern

2011

Journal of Fluids and Structures

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“…Metcalf et al (2006) investigated boundary layer separation around NACA 0024 foil in various Froude numbers by measuring the surface pressure on the model and free surface elevation, and suggested the unsteady PIV measurement as future work. Based on the measured data, Xing et al (2007) and Kandasamy et al (2009) validated their computational fluid dynamics (CFD) codes. The flow around circular cylinders, as well as hydrofoils, is another major concern in surface piercing object problems since it contains unsteady vortex shedding.…”

Section: Performed Velocitymentioning

confidence: 99%

Towed underwater PIV measurement for free-surface effects on turbulent wake of a surface-piercing body

Seol¹,

Seo²,

Rhee³

2013

International Journal of Naval Architecture and Ocean Engineeri

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Unsteady free surface wave-induced separation: Vortical structures and instabilities

Cited by 21 publications

References 37 publications

Shock wave–boundary layer interactions in rectangular inlets: three-dimensional separation topology and critical points

Shock wave–boundary layer interactions in rectangular inlets: three-dimensional separation topology and critical points

The effect of air–water interface on the vortex shedding from a vertical circular cylinder

Towed underwater PIV measurement for free-surface effects on turbulent wake of a surface-piercing body

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