Turbulent drag reduction in a closed flow system: Boundary layer versus bulk effects

1998 ◽  
Vol 10 (2) ◽  
pp. 426-436 ◽  
Author(s):  
Olivier Cadot ◽  
Daniel Bonn ◽  
Stéphane Douady
Keyword(s):  
Boundary Layer ◽  
Drag Reduction ◽  
Flow System ◽  
Layer Versus ◽  
System Boundary ◽  
Turbulent Drag Reduction ◽  
Turbulent Drag

Bubbly Turbulent Drag Reduction Is a Boundary Layer Effect

2007 ◽  
Vol 98 (8) ◽  
Author(s):  
Thomas H. van den Berg ◽  
Dennis P. M. van Gils ◽  
Daniel P. Lathrop ◽  
Detlef Lohse
Keyword(s):  
Boundary Layer ◽  
Drag Reduction ◽  
Turbulent Drag Reduction ◽  
Boundary Layer Effect ◽  
Turbulent Drag ◽  
Layer Effect

scholarly journals Superhydrophobic turbulent drag reduction as a function of surface grating parameters

2014 ◽  
Vol 747 ◽  
pp. 722-734 ◽  
Author(s):  
Hyungmin Park ◽  
Guangyi Sun ◽  
Chang-Jin “CJ” Kim
Keyword(s):  
Boundary Layer ◽  
Drag Reduction ◽  
Turbulent Flows ◽  
Smooth Surface ◽  
Continuous Monitoring ◽  
Laminar Flows ◽  
Turbulent Drag Reduction ◽  
Surface Grating ◽  
Turbulent Drag ◽  
Slip Flows

AbstractDespite the confirmation of slip flows and successful drag reduction (DR) in small-scaled laminar flows, the full impact of superhydrophobic (SHPo) DR remained questionable because of the sporadic and inconsistent experimental results in turbulent flows. Here we report a systematic set of bias-free reduction data obtained by measuring the skin-friction drags on a SHPo surface and a smooth surface at the same time and location in a turbulent boundary layer (TBL) flow. Each monolithic sample consists of a SHPo surface and a smooth surface suspended by flexure springs, all carved out from a $2.7 \times 2.7 {\mathrm{mm}}^{2}$ silicon chip by photolithographic microfabrication. The flow tests allow continuous monitoring of the plastron on the SHPo surfaces, so that the DR data are genuine and consistent. A family of SHPo samples with precise profiles reveals the effects of grating parameters on turbulent DR, which was measured to be as much as ${\sim }75\, \%$.

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.

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