Hairpin Vortex Formation A Case Study For Unsteady Visualization
Download Hairpin Vortex Formation A Case Study For Unsteady Visualization full books in PDF, epub, and Kindle. Read online free Hairpin Vortex Formation A Case Study For Unsteady Visualization ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Author | : |
Publisher | : |
Total Pages | : 14 |
Release | : 1999 |
Genre | : |
ISBN | : |
To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plateboundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.
Author | : Stephen A. Whyte |
Publisher | : |
Total Pages | : 106 |
Release | : 1993 |
Genre | : Flow visualization |
ISBN | : |
Author | : Stephen A. Whyte |
Publisher | : |
Total Pages | : 0 |
Release | : 1993 |
Genre | : Eddies |
ISBN | : |
Author | : Yifei Yu |
Publisher | : Springer Nature |
Total Pages | : 201 |
Release | : |
Genre | : |
ISBN | : 3031536703 |
Author | : |
Publisher | : |
Total Pages | : 16 |
Release | : 1999 |
Genre | : |
ISBN | : |
To better understand the vortex dynamics of coherent structures in turbulent and transitional boundary layers, we consider direct numerical simulation of the interaction between a flat-plate-boundary-layer flow and an isolated hemispherical roughness element. Of principal interest is the evolution of hairpin vortices that form an interlacing pattern in the wake of the hemisphere, lift away from the wall, and are stretched by the shearing action of the boundary layer. Using animations of unsteady three-dimensional representations of this flow, produced by the vtk toolkit and enhanced to operate in a CAVE virtual environment, we identify and study several key features in the evolution of this complex vortex topology not previously observed in other visualization formats.
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 24 |
Release | : 2018-07-03 |
Genre | : |
ISBN | : 9781722215651 |
Recent experimental studies suggest that the hairpin vortex plays an important (and perhaps dominant) role in the dynamics of turbulent flows near walls. In this study a numerical procedure is developed to allow the accurate computation of the trajectory of a 3-D vortex having a small core radius. For hairpin vortices which are convected in a shear flow above a wall, the calculated results show that a 2-D vortex containing a small 3-D disturbance distorts into a complex shape with subsidiary hairpin vortices forming outboard of the original hairpin vortex. As the vortex moves above the wall, it induces unsteady motion in the viscous flow near the wall: numerical solutions suggest that the boundary-layer flow near the wall will ultimately erupt in response to the motion of the hairpin vortex and in the process a secondary hairpin vortex will be created. The computer results agree with recent experimental investigations. Hon, T.-L. and Walker, J. D. A. Glenn Research Center NASA ORDER C-99066-G; RTOP 505-62-21...
Author | : |
Publisher | : |
Total Pages | : 836 |
Release | : 1994 |
Genre | : Aeronautics |
ISBN | : |
Author | : Robert E. Spall |
Publisher | : |
Total Pages | : |
Release | : 1995 |
Genre | : |
ISBN | : |
Author | : M. S. Acarlar |
Publisher | : |
Total Pages | : 267 |
Release | : 1984 |
Genre | : Turbulent boundary layer |
ISBN | : |
A water channel study examined the suggestion that hairpin vortices exist in the near-wall region of turbulent boundary layers and play a key role in the turbulence production process. The hairpin vortices were generated by the interaction of either 1) a hemisphere proturberance or 2) a low-speed fluid region (created by fluid injection techniques) with a subcritical, laminar boundary layer. Shedding characteristics of the hemispheres and the roll-up characteristics of the low-speed regions were determined using hot-films anemometry. Three dimensionality of the flow in the region of hairpin generation results in amplification of disturbances of shorter wavelengths than predicted from two dimensional stability theory. Flow visualization techniques documented the flow patterns created by the presence of the hairpin vortices. Comparision of these patterns with comparable visualizations of fully turbulent boundary layers is quite striking, indicating essential identity between hairpin vortices and many of the predominant flow patterns observed in the near-wall region of a turbulent boundary layer (e.g. streaks, bursts, pockets, ejections, etc.). Velocity measurements made using hot-film anemometry indicate the presence of strong inflectional profiles just down-stream of the hairpin vortex generation region which evolve into fuller profiles with downstream distance, eventually developing a remarkable similarity to a turbulent boundary layer velocity profile. A comprehensive model of the flow process in the near-wall of a turbulent boundary layer is presented.
Author | : |
Publisher | : |
Total Pages | : 258 |
Release | : 1993 |
Genre | : Hydraulic transients |
ISBN | : |