Boundary induced nonlinearities at small Reynolds numbers

Sbragaglia, Mauro; Sugiyama, Kazuyasu

doi:10.1016/j.physd.2007.03.004

Cited by 9 publications

(11 citation statements)

References 38 publications

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“…This is another case where it would be important to complement other numerical works present in the literature [12][13][14][15]. Finally, all results presented in this paper are also useful in the context of ensemble-averaging techniques to formulate effective boundary-condition problems [21][22][23][24][25], an issue which has been renewed recently because of its relevance in small-scale hydrodynamics [26,Chapt. 15].…”

Section: Discussionmentioning

confidence: 73%

Linear shear flow past a hemispherical droplet adhering to a solid surface

Sugiyama

Sbragaglia

2007

J Eng Math

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The properties of a three-dimensional shear flow overpassing a hemispherical droplet resting on a plane wall are investigated. The exact solution is computed as a function of the viscosity ratio between the droplet and the surrounding fluid and generalizes the solution for the hemispherical no-slip bump given in an earlier paper by Price (QJMAM (1985) 38: 93-104). Several expressions, including the torque and the force acting on the drop, are considered as well as the importance of the deformations on the surface for small capillary numbers.

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Section: Discussionmentioning

confidence: 73%

Linear shear flow past a hemispherical droplet adhering to a solid surface

Sugiyama

Sbragaglia

2007

J Eng Math

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“…The Fukagata et al identity has been further extended to the problem of channel flow with mixed boundary conditions by using the reciprocal theorem in Sbragaglia & Sugiyama (2007). Our derivation presented above represents an extension of that work to the TC system.…”

Section: Discussionmentioning

confidence: 91%

“…We note that a general identity providing the effect of the Reynolds shear stress distribution on the skin friction has been recently derived by Fukagata, Iwamoto & Kasagi (2002) for the case of a pressure-driven channel and circular pipe flows. The Fukagata et al identity has been further extended to the problem of channel flow with mixed boundary conditions by using the reciprocal theorem in Sbragaglia & Sugiyama (2007). Our derivation presented above represents an extension of that work to the TC system.…”

Section: Discussionmentioning

confidence: 91%

Microbubbly drag reduction in Taylor–Couette flow in the wavy vortex regime

Sugiyama¹,

Calzavarini²,

Lohse³

2008

J. Fluid Mech.

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We investigate the effect of microbubbles on Taylor-Couette flow by means of direct numerical simulations. We employ an Eulerian-Lagrangian approach with a gas-fluid coupling based on the point-force approximation. Added mass, drag, lift, and gravity are taken into account in the modeling of the motion of the individual bubble. We find that very dilute suspensions of small non-deformable bubbles (volume void fraction below 1%, zero Weber number and bubble Reynolds number 10) induce a robust statistically steady drag reduction (up to 20%) in the wavy vortex flow regime (Re = 600 -2500). The Reynolds number dependence of the normalized torque (the so-called Torque Reduction Ratio (TRR) which corresponds to the drag reduction) is consistent with a recent series of experimental measurements performed by Murai et al. (J. Phys. Conf. Ser. 14, 143 (2005)). Our analysis suggests that the physical mechanism for the torque reduction in this regime is due to the local axial forcing, induced by rising bubbles, that is able to break the highly dissipative Taylor wavy vortices in the system. We finally show that the lift force acting on the bubble is crucial in this process. When neglecting it, the bubbles preferentially accumulate near the inner cylinder and the bulk flow is less efficiently modified.

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“…13 In addition, this analysis was recently extended to include compressible effects on skin friction in turbulent channel flow, pipe flow, and flat plate boundary layer at supersonic Mach numbers. 14 Recently, Sbragaglia and Sugiyama 15 proposed an analytical expression for a skin friction drag on a surface as a function of the volume integral of the velocity field without assuming any particular shape of the surface or flow homogeneity. They used the derived expression to analyze drag modification of the flow in a plane channel with mixedslip boundary conditions at small Reynolds numbers ͓Reϳ O͑1͔͒, as compared to the creeping flow solution.…”

Section: Introductionmentioning

confidence: 99%

“…Although the relation proposed in Ref. 15 can be applied to three-dimensional geometries, it is given in a very general form, without spelling out specific expressions for different dynamical contributions, which is done in Refs. 11 and 14, but only for quasi-two-dimensional cases.…”

Section: Introductionmentioning

confidence: 99%

Theoretical prediction of turbulent skin friction on geometrically complex surfaces

Peet

Sagaut

2009

Physics of Fluids

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This article can be considered as an extension of the paper of Fukagata et al. ͓Phys. Fluids 14, L73 ͑2002͔͒ which derived an analytical expression for the constituent contributions to skin friction in a turbulent channel, pipe, and plane boundary layer flows. In this paper, we extend the theoretical analysis of Fukagata et al. ͑formerly limited to canonical cases with two-dimensional mean flow͒ to a fully three-dimensional situation allowing complex wall shapes. We start our analysis by considering arbitrarily shaped surfaces and then formulate a restriction on a surface shape for which the current analysis is valid. A theoretical formula for skin friction coefficient is thus given for streamwise and spanwise homogeneous surfaces of any shape, as well as some more complex configurations, including spanwise-periodic wavy patterns. The theoretical analysis is validated using the results of large eddy simulations of a turbulent flow over straight and wavy riblets with triangular and knife-blade cross-sections. Decomposition of skin friction into different constituent contributions allows us to analyze the influence of different dynamical effects on a skin friction modification by riblet-covered surfaces.

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Boundary induced nonlinearities at small Reynolds numbers

Cited by 9 publications

References 38 publications

Linear shear flow past a hemispherical droplet adhering to a solid surface

Linear shear flow past a hemispherical droplet adhering to a solid surface

Microbubbly drag reduction in Taylor–Couette flow in the wavy vortex regime

Theoretical prediction of turbulent skin friction on geometrically complex surfaces

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