Skin friction topology in a region enclosed by penetrable boundary

Liu, Tianshu; Woodiga, Sudesh; Ma, Tian

doi:10.1007/s00348-011-1171-6

Cited by 39 publications

(23 citation statements)

References 22 publications

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“…35–38 According to the topological rules, singular points on delta wings were tallied in previous oil streak visualizations. 10 To examine the topological consistency of a skin friction vector field, the Poincare–Bendixson index formula (the P–B formula in short) can be applied, 39 which represents a conservation law for the numbers of isolated singular points enclosed by a closed boundary and boundary switch points. The P–B formula is given by #N-#S=1+(#Z+-#Z-)/2, where #N denotes the number of the nodes, #S the number of the saddles, #Z+ the number of the positive switch points, and #Z- the number of the negative switch points.…”

Section: Topological Consistencymentioning

confidence: 99%

Effects of pitch, yaw, and roll on delta wing skin friction topology

Woodiga

Liu

Ramasamy

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part G:

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High-resolution skin friction fields in separated flows over a 65° delta wing and a 76/40° double-delta wing with different junction fillets are obtained by using quantitative global skin friction diagnostics based on luminescent oil visualizations. The topological features such as separation and attachment lines on these delta wings are identified, and the effects of the pitch, yaw, and roll angles on the skin friction topology are studied systematically. The topological consistency of the measured skin friction fields on the delta wings is examined by using the Poincare–Bendixson index formula.

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Section: Topological Consistencymentioning

confidence: 99%

Effects of pitch, yaw, and roll on delta wing skin friction topology

Woodiga

Liu

Ramasamy

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…A conservation law between the number of isolated singular points and the number of switch points in a singly connected region with a penetrable boundary on a surface is given by the Poincare-Bendixson index formula. 21 For a flow in a region enclosed by a penetrable boundary, there are boundary segments where the flow moves inward and outward across the boundary. If there is a point at which the inflow and outflow segments are divided, this point is called a switch point.…”

Section: B Topological Constraint and Its Implicationmentioning

confidence: 99%

Flow structures of Jupiter's Great Red Spot extracted by using optical flow method

Liu¹,

Wang

Choi

2012

Physics of Fluids

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The flow structures of Jupiter's Great Red Spot (GRS) are studied based on a highresolution velocity field extracted from the Galileo 1996 cloud images of the GRS by using the physics-based optical flow method. The mean transverse velocity profile across the anti-cyclonic near-elliptical collar of the GRS is obtained. The flow structures in the relatively quiescent inner region enclosed by the high-speed collar are revealed at a coarse-grained level. The cyclonic source node in the inner region is identified that is directly associated with the observed cyclonic rotation near the center of the GRS, and its significance in the maintenance of the GRS is explored by using a topological constraint. C 2012 American Institute of Physics.

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“…To interpret the topological structure of a skin friction vector field in such a region, the Poincare-Bendixson index formula (the P-B formula) can be used as a constraint, which essentially is a conservation law for the numbers of the isolated singular points enclosed by a closed boundary and the boundary switch points. A simple derivation of the P-B formula is given by Liu et al (2011). In simple notation, the P-B formula is written as…”

Section: Poincare-bendixson Index Formulamentioning

confidence: 99%

Effects of Yaw and Roll Angles on Skin Friction Topology on Delta Wings

Woodiga

Liu²,

Ramasamy

2012

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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High-resolution skin friction fields in separated flows on delta wings are measured using quantitative global skin friction diagnostics based on luminescent oil visualizations. The effects of the yaw and roll angles on the skin friction topology on delta wings are studied systematically. The topological features like separation and attachment lines and isolated singular points are identified. The conservation law given by the Poincare-Bendixson index formula for the numbers of the isolated singular points and the boundary switch points is used as a general approach to analyze the skin friction topology.

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Skin friction topology in a region enclosed by penetrable boundary

Cited by 39 publications

References 22 publications

Effects of pitch, yaw, and roll on delta wing skin friction topology

Effects of pitch, yaw, and roll on delta wing skin friction topology

Flow structures of Jupiter's Great Red Spot extracted by using optical flow method

Effects of Yaw and Roll Angles on Skin Friction Topology on Delta Wings

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