scholarly journals 3-dimensional particle image velocimetry based evaluation of turbulent skin-friction reduction by spanwise wall oscillation

2020 ◽  
Vol 32 (8) ◽  
pp. 085111
Author(s):  
Kushal U. Kempaiah ◽  
Fulvio Scarano ◽  
Gerrit E. Elsinga ◽  
Bas W. van Oudheusden ◽  
Leon Bermel
Keyword(s):  
Particle Image Velocimetry ◽  
Skin Friction ◽  
Particle Image ◽  
Friction Reduction ◽  
3 Dimensional ◽  
Image Velocimetry ◽  
Wall Oscillation ◽  
Skin Friction Reduction

Effect of Jet Oscillation on the Maximum Impingement Plate Skin Friction

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Adam Ritcey ◽  
Joseph R. McDermid ◽  
Samir Ziada
Keyword(s):  
Flow Field ◽  
Skin Friction ◽  
Field Measurements ◽  
Friction Reduction ◽  
Gas Jet ◽  
Impingement Plate ◽  
Image Velocimetry ◽  
Skin Friction Reduction ◽  
Jet Oscillation ◽  
Quiescent Fluid

The maximum impingement plate skin friction and flow field is measured for an acoustically forced planar impinging gas jet using oil film interferometry (OFI) and particle image velocimetry (PIV), respectively. The study is performed at a jet Reynolds number of Rejet = 11,000 and an impingement distance H, which is set to eight times the nozzle width W. The planar impinging gas jet is forced at the jet nozzle exit using Strouhal numbers StH = 0.39, 0.76, and 1.1, which are similar to those associated with the jet-plate tones measured in air-knife wiping experiments. The flow-field measurements indicate that the jet column oscillates at the applied forcing frequency, and depending on the forcing frequency, organized vortex structures can be identified in the shear layers that impinge on the plate surface. Both of these jet oscillation features result in a reduction in the time-averaged maximum impingement plate skin friction. This skin friction reduction is attributed to momentum loss at the jet centerline caused by increased levels of fluid entrainment and mixing of the surrounding quiescent fluid.

scholarly journals Skin Friction Reduction Characteristics of Nonsmooth Surfaces Inspired by the Shapes of Barchan Dunes

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao-wen Song ◽  
Ming-xiao Zhang ◽  
Peng-zhe Lin
Keyword(s):  
Skin Friction ◽  
Friction Reduction ◽  
Test Results ◽  
Image Velocimetry ◽  
New Type ◽  
Barchan Dunes ◽  
Reduction Effect ◽  
Skin Friction Reduction ◽  
Reduction Characteristics ◽  
Reduction Percentage

A new type of nonsmooth surface inspired by the shape of barchan dunes has been proposed and is intended to reduce skin friction, a major cause of overall drag. Simulations were carried out to obtain skin friction reduction characteristics for the nonsmooth surface using the commercial computational fluid dynamics software Fluent. A realizable k-ε model was employed to assess the influence of the nonsmooth structure on turbulent flow and velocity fields. The numerical simulation results showed that the new nonsmooth surface possesses the desired skin friction reduction effect and that the maximum skin friction reduction percentage reached 33.63% at a fluid speed of 30 m/s. Various aspects of the skin friction reduction mechanism were discussed, including the distribution of velocity vectors and shear stress contours and the variations in boundary layer thickness. The accuracy of the flow field for the nonsmooth unit was further verified by particle image velocimetry test results. The new bionic nonsmooth surface, which exceeds the limitations of existing nonsmooth bionic structures, can effectively reduce skin friction and should provide insights into engineering applications in the future.

scholarly journals Experiments for Verifying Performance of 3-Dimensional Particle Image Velocimetry on Genetic Algorithms

1996 ◽  
Vol 16 (Supplement2) ◽  
pp. 39-42
Author(s):  
Yasuhiko KUNITOU ◽  
Ryu-ichirou OHYAMA ◽  
Hiroo OKANAGA ◽  
Kiyoji KANEKO
Keyword(s):  
Genetic Algorithms ◽  
Particle Image Velocimetry ◽  
Particle Image ◽  
3 Dimensional ◽  
Image Velocimetry
Sign in / Sign up

Export Citation Format

Share Document