Normal vortex interaction with a circular cylinder

Krishnamoorthy, S.; Gossler, Albert A.; Marshall, Jeffrey S.

doi:10.2514/3.14122

Cited by 3 publications

(22 citation statements)

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“…Their results exhibit only slight core deformation (with maximum aspect of ratio of about 1.5) up to the time of boundary-layer separation, with little effect on the inviscid slip velocity at the cylinder surface. Krishnamoorthy et al (1999) also compare inviscid predictions for vortex bending with experimental data and show that the inviscid solutions cease to be valid shortly after the onset of boundary-layer separation from the cylinder. For cases with high impact parameter, boundary-layer separation occurs when the vortex is much closer to the cylinder than for cases with low impact parameter.…”

Section: Introductionmentioning

confidence: 92%

“…The model used by Marshall & Yalamanchili (1994) includes axial vortex core flow and variable core area, but the change in vortex core area owing to stretching by the cylinder is found to be minor except at high values of the impact parameter and after large amounts of stretching. Inviscid core shape deformation is examined by Krishnamoorthy, Gossler & Marshall (1999) by solution of the vortex-cylinder impact using the full Euler equations (in the velocity-vorticity formulation) for a case with high impact parameter. Their results exhibit only slight core deformation (with maximum aspect of ratio of about 1.5) up to the time of boundary-layer separation, with little effect on the inviscid slip velocity at the cylinder surface.…”

Section: Introductionmentioning

confidence: 99%

“…Affes et al (1998) compare results of boundary-layer computations and experimental flow visualization for rotor vortex impact on a cylinder. Krishnamoorthy et al (1999) present flow-visualization results for the evolution of the secondary vorticity after it is ejected from the cylinder, and for the interaction of the secondary vorticity with the primary vortex. These experiments are performed in water using the laser-induced fluorescence (LIF) technique.…”

Section: Introductionmentioning

confidence: 99%

“…View B-B Figure 1. Schematic diagrams showing (a) loop-like and (b) quasi-two-dimensional forms of the ejected secondary vorticity, based on observations from experimental flow visualization (Krishnamoorthy et al 1999).…”

Section: Introductionmentioning

confidence: 99%

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Simulation of normal vortex–cylinder interaction in a viscous fluid

Gossler

Marshall

2001

J. Fluid Mech.

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A computational study of three-dimensional vortex–cylinder interaction is reported for the case where the nominal orientation of the cylinder axis is normal to the vortex axis. The computations are performed using a new tetrahedral vorticity element method for incompressible viscous fluids, in which vorticity is interpolated using a tetrahedral mesh that is refit to the Lagrangian computational points at each timestep. Fast computation of the Biot-Savart integral for velocity is performed using a box-point multipole acceleration method for distant tetrahedra and Gaussian quadratures for nearby tetrahedra. A moving least-square method is used for differentiation, and a flux-based vorticity boundary condition algorithm is employed for satisfaction of the no-slip condition. The velocity induced by the primary vortex is obtained using a filament model and the Navier–Stokes computations focus on development of boundary-layer separation from the cylinder and the form and dynamics of the ejected secondary vorticity structure. As the secondary vorticity is drawn outward by the vortex-induced flow and wraps around the vortex, it has a substantial effect both on the essentially inviscid flow field external to the boundary layer and on the cylinder surface pressure field. Cases are examined with background free-stream velocity oriented in the positive and negative directions along the cylinder axis, with free-stream velocity normal to the cylinder axis, and with no free-stream velocity. Computations with no free-stream velocity and those with free-stream velocity tangent to the cylinder axis exhibit similar secondary vorticity structures, consisting of a vortex loop (or hairpin) that wraps around the primary vortex and is attached to the cylinder boundary layer at two points. Computations with free-stream velocity oriented normal to the cylinder axis exhibit secondary vorticity structure of a markedly different character, in which the secondary eddy remains close to the cylinder boundary and has a quasi-two-dimensional form for an extended time period.

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Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Simulation of normal vortex–cylinder interaction in a viscous fluid

Gossler

Marshall

2001

J. Fluid Mech.

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“…The significant decay of the cavitating trace of the vortex portion in close contact with the wing surface is consistent with the mechanism of vorticity cross-diffusion, which involves the vortex and the boundary layer, as documented by Krishnamoorthy et al . (1999) and Liu & Marshall (2004) for the case of an orthogonal vortex–blade encounter. In fact, the decay of tip vortex cavitation is effective as long as the vortex lies parallel to the wing surface where the process of vorticity cross-diffusion between the vortex and the boundary layer is underway, and goes back to its original strength as it detaches from the wing.…”

Section: Resultsmentioning

confidence: 99%

Underlying mechanisms of propeller wake interaction with a wing

Felli

2020

J. Fluid Mech.

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Resolving vortex-induced pressure fluctuations on a cylinder in rotor wake using fast-responding pressure-sensitive paint

Gregory

2019

Physics of Fluids

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The interaction between rotor wake and a cylinder has been studied experimentally in the current work. The cylinder was placed in close proximity to the rotor plane, and the pressure fluctuations induced by the rotor wake on the cylinder surface were measured by microphones and fast-responding pressure-sensitive paint. Based on the developed data processing methods, challenges such as the low signal-to-noise ratio were resolved and small pressure fluctuations (less than 100 Pa) during the interaction were successfully extracted. The high-resolution vortex-induced pressure field under different blade-cylinder separation distances and rotor collective pitches were compared and analyzed, which clearly showed the effects of tip vortex strength and its evolution. More importantly, for cylinders with different cross section shapes, the pressure footprints left on the surface showed significant distinction in both pressure patterns and overall fluctuation levels. The flat surface would break the structure of the tip vortex and lead to both pressure rise and drop on the surface, while wedge-shaped obstacles would cut the vortex in half and result in two strong pressure drops on both sides. The square cylinder with a 0° installation angle (parallel to the blade) generated the least amount of pressure fluctuation due to its capability of fully breaking the vortex structure during the interaction.

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Normal vortex interaction with a circular cylinder

Cited by 3 publications

References 0 publications

Simulation of normal vortex–cylinder interaction in a viscous fluid

Simulation of normal vortex–cylinder interaction in a viscous fluid

Underlying mechanisms of propeller wake interaction with a wing

Resolving vortex-induced pressure fluctuations on a cylinder in rotor wake using fast-responding pressure-sensitive paint

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