Journal ArticleDOI
Vortex Interactions with Walls
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In this article, the authors discuss the role of vortices in the flight of modern helicopters and aircraft, and discuss the geometrical boundary geometries that act to promote vortex formation.Abstract:
Situations where an effectively irrotational freest ream contains regions of concentrated vorticity are common in external aerodynamics, where vortices are known to play an important role in the flight of modern helicopters (Carr 1988) and aircraft (Cunningham 1989, Mabey 1989). Vortices may arise as a consequence of shedding from some upstream surface or near certain three-dimensional boundary geometries that act to promote vortex formation. Examples of the former type of vortex gen eration include: 1. vortices that trail from the tips of airfoils (Harvey & Perry 1971) and control surfaces on submarines (Lugt 1983), 2. transverse vortices shed from maneuvering airfoil surfaces and helicopter blades in a process known as dynamic stall (McCroskey 1982, Francis & Keesee 1985, Carr 1988), and 3. shedding from stationary obstacles. Geometry-induced creation can occur in any situation where a flow along a wall approaches a surface-mounted obstacle; examples include: 1. airframe features such as wing/body junctions, 2. conning towers on submarines, and 3 . computer chips mounted on electrical circuit boards. Similar geometries are en-read more
Citations
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An experimental study of round jets in cross-flow
TL;DR: In this article, the structure of round jets in cross-flow was studied using flow visualization techniques and flying-hot-wire measurements, restricted to jet to freestream velocity ratios ranging from 2.0 to 6.0.
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High-resolution simulations of the flow around an impulsively started cylinder using vortex methods
TL;DR: In this paper, the development of a viscous incompressible flow generated from a circular cylinder impulsively started into rectilinear motion is studied computationally, and an adaptative numerical scheme based on vortex methods is used to integrate the vorticity/velocity formulation of the Navier-Stokes equations for a wide range of Reynolds numbers (Re = 40 to 9500).
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Vortex-body interactions
TL;DR: In this paper, the authors focus on the underlying flow physics, with the aim of clarifying the origin of the induced loading of vortex interactions and developing creative strategies, distinct from those traditionally employed for control of unstable shear flows.
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The finite-length square cylinder near wake
Hanfeng Wang,Yu Zhou +1 more
TL;DR: In this article, an experimental investigation of the near wake of a finite-length square cylinder, with one end mounted on a flat plate and the other free, was carried out mainly in a closed-loop low-speed wind tunnel at a Reynolds number Red, based on d and the free-stream velocity of 9300 using hot-wire anemometry, laser Doppler anEMometry and particle image velocimetry (PIV).
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Discrete-vortex method with novel shedding criterion for unsteady aerofoil flows with intermittent leading-edge vortex shedding
TL;DR: In this article, a discrete-time, arbitrary-motion, unsteady thin aerofoil theory with discrete-vortex shedding from the leading edge governed by the instantaneous leading-edge suction parameter (LESP) was proposed.
References
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Book
An Introduction to Fluid Dynamics
TL;DR: The dynamique des : fluides Reference Record created on 2005-11-18 is updated on 2016-08-08 and shows improvements in the quality of the data over the past decade.
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Coherent Motions in the Turbulent Boundary Layer
TL;DR: In this paper, the role of coherent structures in the production and dissipation of turbulence in a boundary layer is characterized, summarizing the results of recent investigations, and diagrams and graphs are provided.
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The laminar horseshoe vortex
TL;DR: In this article, smoke flow visualization shows that both steady and unsteady vortex systems exist and pressure distributions beneath both types of vortex systems have been measured and the variation of the horseshoe vortex position on the plane of symmetry upstream of the cylinder has been determined.
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Flowfield produced by trailing vortices in the vicinity of the ground
John K. Harvey,F. J. Perry +1 more
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The Kutta Condition in Unsteady Flow
TL;DR: The Kutta-Joukowsky hypothesis as discussed by the authors was proposed by Kutta and Joukowsky in the first decade of the 20th century to describe the mechanism by which the lift on an airfoil at incidence in a steady unseparated flow is given by potential-flow theory with the unique value of the circulation that removes the inverse-square root velocity singularity at the trailing edge.