Results 1 to 10 of about 50 (49)
Simple model for drag reduction [PDF]
Physical Review E, 2003 Direct Numerical Simulations established that the FENE-P model of viscoelastic flows exhibits the phenomenon of turbulent drag reduction which is caused in experiments by dilute polymeric additives. To gain analytic understanding of the phenomenon we introduce in this Letter a simple 1-dimensional model of the FENE-P equations.
Benzi, Roberto, Procaccia, Itamar
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Theory of Concentration Dependence in Drag Reduction by Polymers and of the Maximum Drag Reduction Asymptote [PDF]
Physical Review Letters, 2004 A simple model of the effect of polymer concentration on the amount of drag reduction in turbulence is presented, simulated, and analyzed. The qualitative phase diagram of drag coefficient versus Reynolds number (Re) is recaptured in this model, including the theoretically elusive onset of drag reduction and the maximum drag reduction (MDR) asymptote ...
BENZI, ROBERTO +3 more
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Drag reduction by compressible bubbles [PDF]
Physical Review E, 2006 Drag reduction by bubbles in stationary turbulent flows is sensitive to the compressibility of the bubbles. Without this dynamical effect the bubbles only renormalize the fluid density and viscosity, an effect that by itself can only lead to a small percentage of drag reduction. We show in this paper that the dynamics of bubbles and their effect on the
T S, Lo +2 more
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Drag reduction on a transonic airfoil
Journal of Fluid Mechanics, 2022 Flow control for turbulent skin-friction drag reduction is applied to a transonic airfoil to improve its aerodynamic performance. The study is based on direct numerical simulations (with up to 1.8 billion cells) of the compressible turbulent flow around a supercritical airfoil, at Reynolds and Mach numbers of $Re_\infty = 3 \times 10^{5}$
Maurizio Quadrio +5 more
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Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2011 The interaction of the overlying turbulent flow with riblets, and its impact on their drag reduction properties are analysed. In the so-called viscous regime of vanishing riblet spacing, the drag reduction is proportional to the riblet size, but for larger riblets the proportionality breaks down, and the drag reduction eventually ...
García Mayoral, Ricardo +1 more
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Fluid Drag Reduction by Magnetic Confinement
Langmuir, 2022 The frictional forces of a viscous liquid flow are a major energy loss issue and severely limit microfluidics practical use. Reducing this drag by more than a few tens of percent remain illusive. Here, we show how cylindrical liquid-in-liquid flow leads to drag reduction of 60-99% for sub mm and mm sized channels, irrespective of whether the viscosity ...
Dev, Arvind Arun +3 more
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Drag reduction by a linear viscosity profile [PDF]
Physical Review E, 2004 Drag reduction by polymers in turbulent flows raises an apparent contradiction: the stretching of the polymers must increase the viscosity, so why is the drag reduced? A recent theory proposed that drag reduction in agreement with experiments is consistent with the effective viscosity growing linearly with the distance from the wall.
DE ANGELIS, ELISABETTA +5 more
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Drag Reduction by Leidenfrost Vapor Layers [PDF]
Physical Review Letters, 2011 We demonstrate and quantify a highly effective drag reduction technique that exploits the Leidenfrost effect to create a continuous and robust lubricating vapor layer on the surface of a heated solid sphere moving in a liquid. Using high-speed video, we show that such vapor layers can reduce the hydrodynamic drag by over 85%.
Vakarelski, Ivan Uriev +3 more
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Drag enhancement and drag reduction in viscoelastic flow [PDF]
Physical Review Fluids, 2018 Creeping flow of polymeric fluid without inertia exhibits elastic instabilities and elastic turbulence accompanied by drag enhancement due to elastic stress produced by flow-stretched polymers. However, in inertia-dominated flow at high $\mbox{Re}$ and low fluid elasticity $El$, a reduction in turbulent frictional drag is caused by an intricate ...
Varshney, Atul, Steinberg, Victor
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Drag Reduction And Heating [PDF]
Progress in Canadian Mechanical Engineering, 2018 Paper presented at 2018 Canadian Society of Mechanical Engineers International Congress, 27-30 May 2018. ; An external force is required to maintain the relative movement of horizontal plates. It is shown that this force is reduced when the plates are subject to a spatially distributed heating.
Floryan, Jerzy M. +2 more
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