Unsteady free-surface wave-induced boundary-layer separation for a surface-piercing NACA 0024 foil: Towing tank experiments

Metcalf, Bryson; Longo, Joseph; Ghosh, Surajeet; Stern, Frederick

doi:10.1016/j.jfluidstructs.2005.09.004

Cited by 36 publications

(19 citation statements)

References 16 publications

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“…The flow topology becomes much more complex when the wave breaking phenomenon that interacts with the horseshoe vortex, also called the vortices necklace. Metcalf et al (2006) experimentally investigate the interactions between the free surface and the boundary layer on a hydrodynamic profile, NACA 0024, at three Froude numbers (0.19, 0.37 and 0.55) associated with three different flow regimes: steady, with reattachement and no reattachement. At low Froude number a calm flow and Kelvin wave system is observed, while for medium Froude numbers, the flow manifests with the phenomenon of breaking the wave, but the streamlines are reattaching the profile, however, maintaining the Kelvin wave profile, while at large Froude number, the current is no longer attached to the hydrofoil, the first wave crest has a considerable height, the energy consumed at breaking the wave is high and the Kelvin wave system is no longer visible.…”

Section: Fascicle XImentioning

confidence: 99%

Wing body junctions in ship hydrodynamics

Ungureanu

Mocanu

Jos³

2019

AnnUGalShipBuilding

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Starting with the 1st of January 2013, all ships greater than 400 gross tons have to comply with design or operational energy efficiency index, in order to reduce the greenhouse emissions. From the naval architect's point of view, the emission reduction measures can be hydrodynamic, structural, technological and operational. The hydrodynamic measures, which are the first that can be taken into consideration in order to reduce the EEDI, are materialized through the optimization of the hull. The Naval Architect may interfere on the bulbous bow, hydrodynamic shoulders, bulb stern, transom or appendages, the drag being then modified by reducing the wave, viscous pressure or frictional resistance components. Another way to improve the hydrodynamics of a ship is the use of Energy Saving Devices (ESD). These are appendages, mounted on the ship hull, developed to improve the flow near the propeller, which operate in the non-uniform wake field of the ship. The flow mechanism around ESDs comes down to wing-body juncture flow problems and, due to their application to the ship appendage flow, they have recently received much attention in ship hydrodynamics. Despite its simple geometric configuration, the wing-body junction flow is a very complicate flow due to the so-called horseshoe vortex system determined by the adverse pressure gradient induced by the presence of the obstacle and the three-dimensional boundary layer separations around the junction. The horseshoe vortex flow affects the drag, lift and causes a persistent lack of uniformity in the wake and is also considered as one source of the noises, vibration and unsteady inflow for the propeller.

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Section: Fascicle XImentioning

confidence: 99%

Wing body junctions in ship hydrodynamics

Ungureanu

Mocanu

Jos³

2019

AnnUGalShipBuilding

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“…Zhang and Stern (1996) and Kandasamy (2001) computed free surface waves around a surface piercing NACA 0024 hydrofoil with a Reynolds averaged Navier Stokes (RANS) solver and simulated the phenomena in the separated flow region at various advancing speeds. 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.…”

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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“…If |E|oU V , the combination of all the errors in D and S is smaller than U V and validation is achieved at the U V level. Metcalf et al (2006) provide data for the mean z and the mean foil surface C P . In addition, the time history of z and the foil surface C P are available over 10 flow times after the initial transients have subsided.…”

Section: Verification and Validationmentioning

confidence: 99%

“…The flow topology was similar to the owl-face pattern. Subsequently, Metcalf et al (2006) identified certain dominant periodic modes from the EFD frequency spectra of z and the foil surface C P for Fr ¼ 0.37, but the flow physics behind these frequencies could not be explained since the complexity of the separation made detailed volume flow measurements difficult.…”

Section: Introductionmentioning

confidence: 99%

“…1 indicate that the broken free surface is a result of the strong turbulence generated underneath the free surface meeting the free surface (Brocchini and Peregrine, 2001). Triple decomposition of the unsteady free surface elevation spectra by Metcalf et al (2006) shows that the average root mean square (r.m.s.) of the visually prominent random fluctuations is an order of magnitude smaller than that of the underlying organized oscillations in the separation region.…”

Section: Introductionmentioning

confidence: 99%

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