The no-slip condition of fluid dynamics

Day, Michael A.

doi:10.1007/bf00717588

Cited by 129 publications

(94 citation statements)

References 12 publications

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“…Surprisingly, this average acceleration has the same sign for both downward (negative) and upward (positive) turbulent velocity excursions, resulting in a net upward time-averaged acceleration which is not equal 0 m s −2 , despite the time average of turbulent velocity fluctuations being, by definition, equal to 0 m s −1 . In essence, this average upward acceleration is a result of the impermeability condition (Day, 1990;Pope, 2000;Stokes, 1851). This condition necessitates that any upward-directed turbulent motion must have been associated with an upward acceleration through time on a trajectory away from the boundary, where the vertical motion must have been zero.…”

Section: Derivationmentioning

confidence: 99%

“…We consider the scales of turbulence in particle-free flow over a smooth, impermeable boundary. The no-slip and impermeability conditions (Day, 1990;Pope, 2000;Stokes, 1851) require that fluid in contact with the boundary has no tangential or perpendicular velocity relative to the boundary. The boundary-perpendicular velocity component w + is therefore equal to 0 at z + = 0, and so is the turbulent component w 2 + .…”

Section: Derivationmentioning

confidence: 99%

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Physical theory for near-bed turbulent particle suspension capacity

2017

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Abstract. The inability to capture the physics of solid-particle suspension in turbulent fluids in simple formulas is holding back the application of multiphase fluid dynamics techniques to many practical problems in nature and society involving particle suspension. We present a force balance approach to particle suspension in the region near no-slip frictional boundaries of turbulent flows. The force balance parameter contains gravity and buoyancy acting on the sediment and vertical turbulent fluid forces; it includes universal turbulent flow scales and material properties of the fluid and particles only. Comparison to measurements shows that = 1 gives the upper limit of observed suspended particle concentrations in a broad range of flume experiments and field settings. The condition of > 1 coincides with the complete suppression of coherent turbulent structures near the boundary in direct numerical simulations of sediment-laden turbulent flow. thus captures the maximum amount of sediment that can be contained in suspension at the base of turbulent flow, and it can be regarded as a suspension capacity parameter. It can be applied as a simple concentration boundary condition in modelling studies of the dispersion of particulates in environmental and man-made flows.

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Section: Derivationmentioning

confidence: 99%

Section: Derivationmentioning

confidence: 99%

Physical theory for near-bed turbulent particle suspension capacity

2017

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“…Stents and ureter walls were set to be rigid with a no-slip condition imposed on each wall. The fluid velocity at all fluid-solid boundaries is equal to that of the solid boundary [8].…”

Section: Governing Equations For Fluid Flow and Numerical Simulationsmentioning

confidence: 99%

Numerical analysis of the effect of side holes of a double J stent on flow rate and pattern

Kim

Choi

Lee

et al. 2015

BME

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Abstract.A double J stent has been used widely these days for patients with a ureteral stenosis or with renal stones and lithotripsy. The stent has multiple side holes in the shaft, which supply detours for urine flow. Even though medical companies produce various forms of double J stents that have different numbers and positions of side holes in the stent, the function of side holes in fluid dynamics has not been studied well. Here, the flow rate and pattern around the side holes of a double J stent were evaluated in curved models of a stented ureter based on the human anatomy and straight models for comparison. The total flow rate was higher in the stent with a greater number of side holes. The inflow and outflow to the stent through the side holes in the curved ureter was more active than in the straight ureter, which means the flow through side holes exists even in the ureter without ureteral stenosis or occlusion and even in the straight ureter. When the diameter of the ureter changed, the in-stent flow rate in the ureter did not change and the extraluminal flow rate was higher in the ureter with a greater diameter.

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“…The no-slip condition for viscous fluid assumes that at a solid boundary, the fluid will have zero velocity relative to the boundary. Recently, the classical no-slip condition has been widely used by many researchers to study the motion of viscous fluid [15].…”

Section: Introductionmentioning

confidence: 99%

Unsteady rotational motion of a composite sphere in a viscous fluid using stress jump condition

Miari

Ashmawy

2018

Journal of Taibah University for Science

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The unsteady rotational motion of a composite sphere, consisting of a solid core surrounded by a porous shell, in an incompressible viscous fluid is discussed using Brinkman's formula. The composite sphere is assumed to rotate about z-axis with time-dependent angular velocity. Laplace transform technique is utilized to obtain the solution of the problem. The inversion of Laplace transform is obtained analytically using contour integration. An analytical and numerical interpretation of the Torque exerted by the fluid on the porous surface is obtained. The effect of stress jump condition and permeability coefficient is discussed and some special cases are deduced. ARTICLE HISTORY

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The no-slip condition of fluid dynamics

Cited by 129 publications

References 12 publications

Physical theory for near-bed turbulent particle suspension capacity

Physical theory for near-bed turbulent particle suspension capacity

Numerical analysis of the effect of side holes of a double J stent on flow rate and pattern

Unsteady rotational motion of a composite sphere in a viscous fluid using stress jump condition

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