Effect of a splitter plate on the dynamics of a vortex pair

Rabinovitch, Jason; Brion, Vincent; Blanquart, Guillaume

doi:10.1063/1.4737878

Cited by 13 publications

(3 citation statements)

References 25 publications

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“…The method is defined as a non-local scheme by [26] and has been applied successfully to PIV data (e.g. [27,28] and [29]). The γ 2 criterion is the non-Galilean invariant version of the γ 1 criterion, as the local convection velocity is subtracted.…”

Section: Vortex Detection Criteriamentioning

confidence: 99%

The leading-edge vortex of yacht sails

Arredondo-Galeana

Viola

2018

Ocean Engineering

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It has been suggested that a stable Leading Edge Vortex (LEV) can be formed from the sharp leading edge of asymmetric spinnakers. If the LEV remains stably attached to the leading edge, it provides an increase in the thrust force. Until now, however, the existence of a stable and attached LEV has only been shown by numerical simulations. In the present work we experimentally verify, for the first time, that a stable LEV can be formed on an asymmetric spinnaker. We tested a 3D printed rigid sail in a water flume at a chord-based Reynolds number of ca. 104 . The sail was tested in isolation (no hull and rigging) at an incidence with the flow equivalent to an apparent wind angle of 55• and a heel angle of 10 • . The flow field was measured with particle image velocimetry over horizontal cross sections. We found that on the leeward side of the sail, the flow separates at the leading edge reattaching further downstream and forming a stable LEV. The LEV grows in diameter from the root to the tip of the sail, where it merges with the tip vortex. We detected the LEV using the γ 1 and γ 2 criteria, and we verified its stability over time. The lift contribution provided by the LEV was computed solving a complex potential model of each sail section. This analysis showed that the LEV provides more than 10% of the total sail's lift. These findings suggests that the performance of asymmetric spinnakers could be significantly enhanced by promoting a stable LEV.

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Section: Vortex Detection Criteriamentioning

confidence: 99%

The leading-edge vortex of yacht sails

Arredondo-Galeana

Viola

2018

Ocean Engineering

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“…A guide on CUDA programming is available at [24]. This algorithm was used by [25], [26], and [27]. It is a local iterative gradientbased cross-correlation optimization algorithm which yields dense velocity fields, i.e.…”

Section: Backward-facing Step Geometrymentioning

confidence: 99%

Real-time planar flow velocity measurements using an optical flow algorithm implemented on GPU

Gautier

Aider

2014

J Vis

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This paper presents a high-speed implementation of an optical flow algorithm which computes in real-time planar velocity fields in an experimental flow. Real-time computations of the flow velocity field allow the experimentalist to have instantaneous access to quantitative features of the flow. This can be very useful in many situations: fast evaluation of the performances and characteristics of a new setup, design optimization, easier and faster parametric studies, etc. It can also be used as a visual sensor for an input in closed-loop flow control experiments where fast estimation of the state of the flow is needed. The algorithm is implemented on a graphics processor unit. The accuracy of the computation is demonstrated. Computation speed and scalability of the processing are highlighted along with guidelines for further improvements. The system architecture is flexible, scalable and can be adapted on the fly in order to process higher resolutions or achieve higher precision. The setup is applied on a backward-facing step flow in a hydrodynamic channel. For validation purposes, classical particle image velocimetry (PIV) is used to compare with instantaneous optical flow measurements. The important flow characteristics like the dynamics of the recirculation bubble, computed in real time for the first time, are well recovered. The accuracy of real-time optical flow measurements is comparable to off-line PIV computations.

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“…Simulations of a single vortex passing along a viscous no-slip also exhibited the Crow instability yet with a damped growth rate. Experiments by [23] examined the evolution of the Crow instability for a vortex pair and a single vortex above a flat plate, where the Crow The present research effort explores the temporal evolution and stability characteristics of a counter-rotating trailing vortex pair in the presence of an inviscid planar surface. The mathematical model is formulated in Sect.…”

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confidence: 99%

Linear stability of a counter-rotating vortex pair approaching an inviscid wall

Herndon

Jaworski

2023

Theor. Comput. Fluid Dyn.

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The influence of an inviscid planar wall on the temporal development of the long-wavelength instability of a trailing vortex pair is formulated analytically and studied numerically. The center positions and deformation perturbations of the trailing vortices are marched forward in time via the vortex filament method based on Biot–Savart induction. An optimal perturbation analysis of the vortex system determines the wavenumber and initial condition that yield maximum perturbation growth for any instant in time. Direct integration of the vortex system highlights its sensitivity to initial conditions and the time dependence of the optimal wavenumber, which are not features of the classical free vortex pair. As the counter-rotating vortex pair approaches the wall, the wavenumber for maximum growth shifts to a higher value than what is predicted for the Crow instability of vortices in an unbounded fluid. The present analysis demonstrates that the local suppression of the Crow instability near a planar wall may be described without recourse to viscous fluid arguments. Graphical abstract

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Effect of a splitter plate on the dynamics of a vortex pair

Cited by 13 publications

References 25 publications

The leading-edge vortex of yacht sails

The leading-edge vortex of yacht sails

Real-time planar flow velocity measurements using an optical flow algorithm implemented on GPU

Linear stability of a counter-rotating vortex pair approaching an inviscid wall

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