Viscous Drag Reduction Examined in the Light of a New Model of Wall Turbulence

1969 ◽  
pp. 383-407 ◽  
Author(s):  
Thomas J. Black
Keyword(s):  
Drag Reduction ◽  
Wall Turbulence ◽  
Viscous Drag ◽  
New Model

scholarly journals Experimental investigations of turbulent drag reduction by surface-embedded grooves

2007 ◽  
Vol 590 ◽  
pp. 107-116 ◽  
Author(s):  
B. FROHNAPFEL ◽  
J. JOVANOVIĆ ◽  
A. DELGADO
Keyword(s):  
Drag Reduction ◽  
Functional Space ◽  
Wall Turbulence ◽  
Surface Topology ◽  
Viscous Drag ◽  
Experimental Investigations ◽  
Turbulent Drag Reduction ◽  
Velocity Fluctuations ◽  
Turbulent Drag ◽  
Near Wall Turbulence

Consideration of near-wall turbulence in the functional space that emphasizes the level of anisotropy of the velocity fluctuations not only provides an understanding of th causative physics behind remarkable effects of turbulent drag reduction, but also lead to the logical design of a surface topology which is shown experimentally to be capable o producing a significant reduction of viscous drag which far exceeds what has been achieved so far.

scholarly journals Actuation response model from sparse data for wall turbulence drag reduction

2020 ◽  
Vol 5 (7) ◽  
Author(s):  
Daniel Fernex ◽  
Richard Semaan ◽  
Marian Albers ◽  
Pascal S. Meysonnat ◽  
Wolfgang Schröder ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Sparse Data ◽  
Wall Turbulence ◽  
Response Model

Recent developments in fabricating drag reduction surfaces covering biological sharkskin morphology

2016 ◽  
Vol 32 (1) ◽  
Author(s):  
Yuehao Luo ◽  
Xia Xu ◽  
Dong Li ◽  
Wen Song
Keyword(s):  
Global Warming ◽  
Drag Reduction ◽  
Rapid Development ◽  
Three Dimensional ◽  
Viscous Drag ◽  
Environment Protection ◽  
Uv Curable ◽  
Recent Developments ◽  
Potential Benefits ◽  
Energy Shortage

AbstractWith the rapid development of science and technology, increasing research interests have been focused on environment protection, global warming, and energy shortage. At present, reducing friction force as much as possible has developed into an urgent issue. Sharkskin effect has the potential ability to lower viscous drag on the fluid-solid interface in turbulence, and therefore, how to fabricate bio-inspired sharkskin surfaces is progressively becoming the hot topic. In this review, various methods of fabricating drag reduction surfaces covering biological sharkskin morphology are illustrated and discussed systematically, mainly involving direct bio-replicated, synthetic fabricating, bio/micro-rolling, enlarged solvent-swelling, drag reduction additive low-releasing, trans-scale enlarged three-dimensional fabricating, flexible printing, large-proportional shrunken bio-replicating, ultraviolet (UV) curable painting, and stretching deformed methods. The overview has the potential benefits in better acquainting with the recent research status of fabricating sharkskin surfaces covering the biological morphology.

scholarly journals Global effect of local skin friction drag reduction in spatially developing turbulent boundary layer

2016 ◽  
Vol 805 ◽  
pp. 303-321 ◽  
Author(s):  
A. Stroh ◽  
Y. Hasegawa ◽  
P. Schlatter ◽  
B. Frohnapfel
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Control Region ◽  
Reduction Rate ◽  
Wall Turbulence ◽  
Local Skin ◽  
Control Schemes ◽  
Local Skin Friction ◽  
Friction Drag Reduction

A numerical investigation of two locally applied drag-reducing control schemes is carried out in the configuration of a spatially developing turbulent boundary layer (TBL). One control is designed to damp near-wall turbulence and the other induces constant mass flux in the wall-normal direction. Both control schemes yield similar local drag reduction rates within the control region. However, the flow development downstream of the control significantly differs: persistent drag reduction is found for the uniform blowing case, whereas drag increase is found for the turbulence damping case. In order to account for this difference, the formulation of a global drag reduction rate is suggested. It represents the reduction of the streamwise force exerted by the fluid on a plate of finite length. Furthermore, it is shown that the far-downstream development of the TBL after the control region can be described by a single quantity, namely a streamwise shift of the uncontrolled boundary layer, i.e. a changed virtual origin. Based on this result, a simple model is developed that allows the local drag reduction rate to be related to the global one without the need to conduct expensive simulations or measurements far downstream of the control region.

Viscous Drag Reduction in Adverse Pressure Gradient Boundary Layers

2019 ◽  
Author(s):  
Katherine K. Disser ◽  
Thomas C. Corke ◽  
Flint O. Thomas ◽  
Alan Duong ◽  
Samaresh Midya
Keyword(s):  
Pressure Gradient ◽  
Drag Reduction ◽  
Boundary Layers ◽  
Adverse Pressure Gradient ◽  
Viscous Drag

On the Effects of Aero Boundary Layer Control on Pressure Drag Reduction in Supercavitating Bodies

2005 ◽  
Author(s):  
Yasmin Khakpour ◽  
Miad Yazdani
Keyword(s):  
Boundary Layer ◽  
Drag Reduction ◽  
Pressure Distribution ◽  
Constant Pressure ◽  
Viscous Drag ◽  
Cavity Surface ◽  
Gradient Flows ◽  
Supercavitating Vehicles ◽  
Pressure Drag ◽  
Layer Control

Supercavitation is known as the way of viscous drag reduction for the projectiles, moving in the liquid phase. In recent works, there is distinct investigation between cavitation flow and momentum transfer far away from the cavity surface. However, it seems that there is strong connection between overall flow and what takes place in the sheet cavity where a constant pressure distribution is assumed. Furthermore as we’ll see, pressure distribution on cavity surface caused due to overall conditions, induct nonaxisymetric forces and they may need to be investigated. Primarily we describe how pressure distribution into the cavity can cause separation of the aero boundary layer. Then we present some approaches by which this probable separation can be controlled. Comparisons of several conditions exhibits that at very low cavitation numbers, constant pressure assumption fails particularly for gradient shaped profiles and separation is probable if the flow is sufficiently turbulent. Air injection into the NATURALLY FORMED supercavity is found as an effective way to delay probable separation and so significant pressure drag reduction is achieved. In addition, the position of injection plays a major role to control the aero boundary layer and it has to be considered. Moreover, electromagnetic forces cause to delay or even prevent separation in high pressure gradient flows and interesting results obtained in this regard shows significant drag reduction in supercavitating vehicles.

Turbulent viscous drag reduction with thin-element riblets

AIAA Journal ◽  
1988 ◽  
Vol 26 (4) ◽  
pp. 496-498 ◽  
Author(s):  
B. Lazos ◽  
S. P. Wilkinson
Keyword(s):  
Drag Reduction ◽  
Viscous Drag
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