Frequency Response of Fluid Lines With Turbulent Flow

A single boundary layer model to account for transient viscous effects is applied to small amplitude sinusoidally disturbed turbulent flow in a tube. The viscous dissipation is calculated using a transfer function relating the local boundary layer velocity gradient to the core velocity. A simple expression for the attenuation factor is derived and the analytical results are shown to be in excellent agreement with previously reported experimental data.

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A Boundary-Layer Theory for Transient Viscous Losses in Turbulent Flow

Journal of Basic Engineering ◽

10.1115/1.3425158 ◽

1970 ◽

Vol 92 (4) ◽

pp. 865-873 ◽

Cited By ~ 15

Author(s):

D. J. Wood ◽

J. E. Funk

Keyword(s):

Boundary Layer ◽

Turbulent Flow ◽

Numerical Solutions ◽

Transient Flow ◽

Viscous Effects ◽

Viscous Losses ◽

Rapid Flow ◽

Flow Information ◽

Layer Velocity ◽

Good Agreement

A laminar boundary-layer model is proposed to account for viscous losses during the transient turbulent flow of a liquid in a tube. In this model, inviscid slug flow is assumed for the core and all viscous effects are assumed to occur in the boundary layer. The transient boundary-layer velocity distribution is determined as a function of a prescribed variation in core velocity and the associated pressure gradient. Both analytical and numerical solutions are presented. This transient flow information is used to calculate local and integrated energy dissipation rates which are then combined, with one-dimensional energy analyses. The result is a prediction of the decrease in pressure-wave magnitude due to viscous dissipation, and a comparison is made with experimental data for rapid flow extinction. Good agreement between the observed and predicted results is obtained.

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Thermophoretic Deposition of Particles in Natural Convection Flow From a Vertical Plate

Journal of Heat Transfer ◽

10.1115/1.3247410 ◽

1985 ◽

Vol 107 (2) ◽

pp. 272-276 ◽

Cited By ~ 53

Author(s):

M. Epstein ◽

G. M. Hauser ◽

R. E. Henry

Keyword(s):

Boundary Layer ◽

Turbulent Flow ◽

Simple Expression ◽

Convection Flow ◽

Convection Boundary Layer ◽

Boundary Layer Equations ◽

Fixed Set ◽

Laminar And Turbulent Flow ◽

The Heat Transfer Coefficient ◽

Free Convection Boundary Layer

An analysis is made for thermophoretic transport of small particles through a free-convection boundary layer adjacent to a cold, vertical deposition surface. The gas-particle, boundary layer equations are solved numerically for both laminar and turbulent flow. The numerical results indicate that, for a fixed set of boundary conditions and physical properties, the particle concentration at the wall in the laminar flow is very close to that in turbulent flow. A simple expression is suggested relating the particle transport rate to the heat transfer coefficient for the laminar and turbulent flow regimes.

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Mathematical modeling of the intensified heat transfer at a turbulent flow in longitudinal-flow tube bundles with lateral ring grooves with the aid of a compound three-layer model of the turbulent boundary layer

Vestnik of Nosov Magnitogorsk State Technical University ◽

10.18503/1995-2732-2016-14-1-109-115 ◽

2016 ◽

Vol 14 (1) ◽

pp. 109-115

Author(s):

I.E. Lobanov ◽

Keyword(s):

Mathematical Modeling ◽

Heat Transfer ◽

Boundary Layer ◽

Turbulent Boundary Layer ◽

Turbulent Flow ◽

Longitudinal Flow ◽

Layer Model ◽

Flow Tube ◽

Tube Bundles

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Flow along a long thin cylinder

Journal of Fluid Mechanics ◽

10.1017/s0022112008000542 ◽

2008 ◽

Vol 602 ◽

pp. 1-37 ◽

Cited By ~ 26

Author(s):

O. R. TUTTY

Keyword(s):

Boundary Layer ◽

Reynolds Number ◽

Turbulent Flow ◽

Experimental Results ◽

Surface Shear Stress ◽

Mean Flow ◽

Layer Model ◽

Thin Cylinder ◽

Boundary Layer Model ◽

The Mean

Two different approaches have been used to calculate turbulent flow along a long thin cylinder where the flow is aligned with the cylinder. A boundary-layer code is used to predict the mean flow for very long cylinders (length to radius ratio of up to O(106)), with the effects of the turbulence estimated through a turbulence model. Detailed comparison with experimental results shows that the mean properties of the flow are predicted within experimental accuracy. The boundary-layer model predicts that, sufficiently far downstream, the surface shear stress will be (almost) constant. This is consistent with experimental results from long cylinders in the form of sonar arrays. A periodic Navier–Stokes problem is formulated, and solutions generated for Reynolds number from 300 to 5×104. The results are in agreement with those from the boundary-layer model and experiments. Strongly turbulent flow occurs only near the surface of the cylinder, with relatively weak turbulence over most of the boundary layer. For a thick boundary layer with the boundary-layer thickness much larger than the cylinder radius, the mean flow is effectively constant near the surface, in both temporal and spatial frameworks, while the outer flow continues to develop in time or space. Calculations of the circumferentially averaged surface pressure spectrum show that, in physical terms, as the radius of the cylinder decreases, the surface noise from the turbulence increases, with the maximum noise at a Reynolds number of O(103). An increase in noise with a decrease in radius (Reynolds number) is consistent with experimental results.

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Unsteady dynamics of turbulent flow in the wakes of barchan dunes modulated by overlying boundary-layer structure

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.476 ◽

2021 ◽

Vol 920 ◽

Author(s):

Nathaniel R. Bristow ◽

Gianluca Blois ◽

James L. Best ◽

Kenneth T. Christensen

Keyword(s):

Boundary Layer ◽

Turbulent Flow ◽

Layer Structure ◽

Boundary Layer Structure ◽

Barchan Dunes

Abstract

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The Influence of Boundary Layer Velocity Gradients and Bed Proximity on Vortex Shedding From Free Spanning Pipelines

Journal of Energy Resources Technology ◽

10.1115/1.3231028 ◽

1984 ◽

Vol 106 (1) ◽

pp. 70-78 ◽

Cited By ~ 78

Author(s):

A. J. Grass ◽

P. W. J. Raven ◽

R. J. Stuart ◽

J. A. Bray

Keyword(s):

Boundary Layer ◽

Strouhal Number ◽

Vortex Shedding ◽

Combined Effects ◽

Maximum Increase ◽

Velocity Gradients ◽

Large Velocity ◽

Layer Velocity ◽

Vortex Shedding Frequency ◽

Shedding Frequency

The paper summarizes the results of a laboratory study of the separate and combined effects of bed proximity and large velocity gradients on the frequency of vortex shedding from pipeline spans immersed in the thick boundary layers of tidal currents. This investigation forms part of a wider project concerned with the assessment of span stability. The measurements show that in the case of both sheared and uniform approach flows, with and without velocity gradients, respectively, the Strouhal number defining the vortex shedding frequency progressively increases as the gap between the pipe base and the bed is reduced below two pipe diameters. The maximum increase in vortex shedding Strouhal number, recorded close to the bed in an approach flow with large velocity gradients, was of the order of 25 percent.

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