COMPUTATIONAL AND EXPERIMENTAL STUDIES OF AN ACTIVE SKIN FOR TURBULENT DRAG REDUCTION

2002 ◽  
Author(s):  
Othon Rediniotis ◽  
Dimitris Lagoudas ◽  
Raghavendran Mani ◽  
Lance Traub ◽  
George Karniadakis ◽  
...  
Keyword(s):  
Drag Reduction ◽  
Experimental Studies ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

Liquid-infused surfaces as a passive method of turbulent drag reduction

2017 ◽  
Vol 824 ◽  
pp. 688-700 ◽  
Author(s):  
M. K. Fu ◽  
I. Arenas ◽  
S. Leonardi ◽  
M. Hultmark
Keyword(s):  
Drag Reduction ◽  
Turbulent Flows ◽  
Experimental Studies ◽  
Turbulent Channel Flow ◽  
Superhydrophobic Surfaces ◽  
Fluid Interfaces ◽  
Turbulent Drag Reduction ◽  
Liquid Lubricant ◽  
Passive Method ◽  
Turbulent Drag

Liquid-infused surfaces present a novel, passive method of turbulent drag reduction. Inspired by the Nepenthes Pitcher Plant, liquid-infused surfaces utilize a lubricating fluid trapped within structured roughness to facilitate a slip at the effective surface. The conceptual idea is similar to that of superhydrophobic surfaces, which rely on a lubricating air layer, whereas liquid-infused surfaces use a preferentially wetting liquid lubricant to create localized fluid–fluid interfaces. Maintaining the presence of these slipping interfaces has been shown to be an effective method of passively reducing skin friction drag in turbulent flows. Given that liquid-infused surfaces have only recently been considered for drag reduction applications, there is no available framework to relate surface and lubricant characteristics to any resulting drag reduction. Here we use results from direct numerical simulations of turbulent channel flow over idealized, liquid-infused grooves to demonstrate that the drag reduction achieved using liquid-infused surfaces can be described using the framework established for superhydrophobic surfaces. These insights can be used to explain drag reduction results observed in experimental studies of lubricant-infused surfaces. We also demonstrate how a liquid-infused surface can reduce drag even when the viscosity of the lubricant exceeds that of the external fluid flow, which at first glance can seem counter-intuitive.

scholarly journals Fibre-induced drag reduction

2008 ◽  
Vol 602 ◽  
pp. 209-218 ◽  
Author(s):  
J. J. J. GILLISSEN ◽  
B. J. BOERSMA ◽  
P. H. MORTENSEN ◽  
H. I. ANDERSSON
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Reynolds Number ◽  
Drag Reduction ◽  
Elastic Layer ◽  
Turbulent Drag Reduction ◽  
Rigid Polymer ◽  
Fibre Concentration ◽  
Induced Drag ◽  
Turbulent Drag

We use direct numerical simulation to study turbulent drag reduction by rigid polymer additives, referred to as fibres. The simulations agree with experimental data from the literature in terms of friction factor dependence on Reynolds number and fibre concentration. An expression for drag reduction is derived by adopting the concept of the elastic layer.

scholarly journals Turbulent drag reduction in a dilute polymeric solution flowing through a fiber-implanted circular pipe.

1988 ◽  
Vol 21 (4) ◽  
pp. 441-443
Author(s):  
HIROTSUGU HATTORI ◽  
TOMOO YAMAUCHI ◽  
SEIICHI TANABE ◽  
HIDEOMI MATSUDA
Keyword(s):  
Drag Reduction ◽  
Circular Pipe ◽  
Turbulent Drag Reduction ◽  
Polymeric Solution ◽  
Turbulent Drag

Turbulent drag reduction by spanwise oscillations of a ribbed surface

2013 ◽  
Vol 48 (4) ◽  
pp. 461-470 ◽  
Author(s):  
I. S. Vodop’yanov ◽  
N. V. Nikitin ◽  
S. I. Chernyshenko
Keyword(s):  
Drag Reduction ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

scholarly journals Turbulent drag reduction by polymer additives in parallel-shear flows

2017 ◽  
Vol 827 ◽  
Author(s):  
Bayode E. Owolabi ◽  
David J. C. Dennis ◽  
Robert J. Poole
Keyword(s):  
Drag Reduction ◽  
Cross Sections ◽  
Shear Flows ◽  
Extensional Flow ◽  
Relaxation Times ◽  
Weissenberg Number ◽  
Mechanical Degradation ◽  
Turbulent Drag Reduction ◽  
Time Resolved ◽  
Turbulent Drag

In this study, we experimentally investigate the turbulent drag-reduction (DR) mechanism in flow through ducts of circular, rectangular and square cross-sections using two grades of polyacrylamide in aqueous solution having different molecular weights and various semidilute concentrations. Specifically, we explore the relationship between drag reduction and fluid elasticity, purposely exploiting the mechanical degradation of polymer molecules to vary their rheological properties. We also obtain time-resolved velocity data for various DR levels using particle image velocimetry and laser Doppler velocimetry. Elasticity is quantified via relaxation times determined from uniaxial extensional flow using a capillary breakup apparatus. A plot of DR against Weissenberg number ($Wi$) is found to approximately collapse the data, with the onset of DR occurring at $Wi\approx 0.5$ and the maximum drag-reduction asymptote being approached for $Wi\gtrsim 5$. Thus quantitative predictions of DR in a range of shear flows can be made from a single measurable material property of a polymer solution, at least for this particular flexible linear polymer.

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