Intermediate layer scaling in the inner layer of turbulent pipe flow and zero-pressure-gradient boundary layer

2021 ◽  
Vol 33 (11) ◽  
pp. 115125
Author(s):  
J. Dey
Keyword(s):  
Boundary Layer ◽  
Pressure Gradient ◽  
Pipe Flow ◽  
Intermediate Layer ◽  
Turbulent Pipe Flow

A Numerical Study of Pulsed Turbulent Pipe Flow

1985 ◽  
Vol 107 (2) ◽  
pp. 205-211 ◽  
Author(s):  
V. Reddy ◽  
J. B. McLaughlin ◽  
R. J. Nunge
Keyword(s):  
Pressure Gradient ◽  
Production Rate ◽  
Pipe Flow ◽  
Numerical Study ◽  
Phase Relationship ◽  
Turbulent Pipe Flow ◽  
Wall Region ◽  
Pulsation Frequency ◽  
Axial Pressure Gradient ◽  
Turbulence Production

A numerical study of fully developed turbulent pipe flow due to a sinusoidally varying (with respect to time) axial pressure gradient was carried out using a nonlinear three-dimensional model. Pseudospectral methods were used to solve the model equations. The pulsation frequency was characteristic of the wall region eddies in steady turbulent flow. Attention was focused on the viscous wall region, and it was found that the mean profiles of axial velocity, fluctuation intensities, and turbulence production rate were essentially the same as in steady flow. The fluctuation intensities and the turbulence production rate showed a definite phase relationship to the pressure gradient. The turbulence production rate was the largest at the time in the pulsation cycle at which the largest adverse pressure gradient existed.

Rough wall turbulent boundary layers

1969 ◽  
Vol 37 (2) ◽  
pp. 383-413 ◽  
Author(s):  
A. E. Perry ◽  
W. H. Schofield ◽  
P. N. Joubert
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Pressure Gradient ◽  
Pipe Flow ◽  
Boundary Layer Flow ◽  
Shear Velocity ◽  
Rough Wall ◽  
Pipe Diameter ◽  
Boundary Layer Development ◽  
Layer Flow

This paper describes a detailed experimental study of turbulent boundary-layer development over rough walls in both zero and adverse pressure gradients. In contrast to previous work on this problem the skin friction was determined by pressure tapping the roughness elements and measuring their form drag.Two wall roughness geometries were chosen each giving a different law of behaviour; they were selected on the basis of their reported behaviour in pipe flow experiments. One type gives a Clauser type roughness function which depends on a Reynolds number based on the shear velocity and on a length associated with the size of the roughness. The other type of roughness (typified by a smooth wall containing a pattern of narrow cavities) has been tested in pipes and it is shown here that these pipe results indicate that the corresponding roughness function does not depend on roughness scale but depends instead on the pipe diameter. In boundary-layer flow the first type of roughness gives a roughness function identical to pipe flow as given by Clauser and verified by Hama and Perry & Joubert. The emphasis of this work is on the second type of roughness in boundary-layer flow. No external length scale associated with the boundary layer that is analogous to pipe diameter has been found, except perhaps for the zero pressure gradient case. However, it has been found that results for both types of roughness correlate with a Reynolds number based on the wall shear velocity and on the distance below the crests of the elements from where the logarithmic distribution of velocity is measured. One important implication of this is that a zero pressure gradient boundary layer with a cavity type rough wall conforms to Rotta's condition of precise self preserving flow. Some other implications of this are also discussed.

Drag Reduction Characteristics of Solutions of Macromolecules In Turbulent Pipe Flow

1964 ◽  
Vol 4 (03) ◽  
pp. 203-214 ◽  
Author(s):  
J.G. Savins
Keyword(s):  
Pressure Drop ◽  
Pressure Gradient ◽  
Drag Reduction ◽  
Skin Friction ◽  
Boundary Layers ◽  
Pipe Flow ◽  
Single Phase ◽  
Turbulent Pipe Flow ◽  
Turbulent Motion ◽  
Flow Rates

Abstract Certain types of macromolecules added to otter and salt solutions flouting in turbulent motion can reduce the pressure gradient. Alternatively, the volumetric capacity of a pipe for these fluids is increased by the presence of these material. Examples presented show that the drag reduction can become significant. Thus, the presence of 0.28 per cent of a gum derivative in a solution of sodium chloride flowing at 200 gal/min in a 1.89- in. pipe yields a pressure drop which is 0.44 of the single-phase drop measured under the same conditions of turbulent flow; the addition of 0.1 per cent of a vinyl derivative to a 1-in. water line yields a through put capacity which is 1.78 of the single-phase capacity at the same pressure drop. It is further shown that these phenomena are distinctly different from previous observations with other classes of non-Newtonian systems. There a simple lowering of friction factors below the levels predicted from the resistance laws for Newtonian fluids is associated with a suppression of turbulent motion. A rational physical explanation for drag reduction is advanced. Briefly, the proposed mechanism is a storage by the molecular elastic elements of the macromolecules in solution of the kinetic energy of the turbulent motion. Introduction This study was inspired by a recent review of some paradoxical drag reduction phenomena in turbulent pipe flow. Under very moderate conditions of turbulent flow, the pressure gradient necessary to pump solutions containing certain specific kinds of polymers, fibers and metallic soaps may become appreciably lower than that required to pump the solvent, i.e., water or a low-viscosity hydrocarbon, under identical flow rates in the same conduit. As shown by our review, this phenomenon of drag reduction in turbulent duct flow was first noted during the second world war, apparently arising in connection with the development of flame warfare weapons. Since that time several papers illustrating this phenomenon have appeared: Toms, Oldroyd, Agoston et al., Bundrant and Matthews, Robertson and Mason, Ousterhout and Hall, Daily and Bugliarello, Lummus, Anderson, and Fox. That there are practical applications for techniques which increase discharge or decrease the pressure necessary to transport a liquid through a pipeline is illustrated in the patents which have issued which take advantage of this peculiar phenomenon, e.g., Mysels, Dever, Harbour, and Seifert. One also finds fragmentary evidence of this effect in the data pertaining to a few of the polymeric solutions studied by Shaver and Dodge. However, these investigators were concerned with the development of friction factor vs Reynolds number correlations for a variety of non-Newtonian solutions and suspensions, rather than in a study of drag reduction. A similar kind of drag reduction effect has been observed in gases. Sproull, for example, reports that adding dust to air flowing in turbulent motion through a pipe results in a lowering of the pressure gradient at identical flow rates. There are also military applications for reducing the drag on hydrodynamic vehicles. For example, the possibility of injecting a rheologically complex fluid into the boundary layers of bodies to reduce the skin friction has been investigated by Fabula and Granville. Along somewhat different lines are the drag reduction studies of Kramer. He has shown that skin friction can be reduced by covering the surface of a vehicle with a flexible skin. The effect is apparently due to the boundary layer being stabilized by the presence of the skin. Drag reduction by means of coexisting gas and liquid boundary layers, e.g., film boiling and continuous gas injection, has been proposed by Bradfield, Barkdoll, and Byrne, Cess and Sparrow, Sparrow, Jonsson, and Eckert. Here the skin friction occurs between a vapor and a surface rather than between a liquid and a surface. There are several references in the literature to friction-factor correlations for non-Newtonian solutions and suspensions: Shaver and Merrill, Dodge and Metzner, Clapp, and Thomas. SPEJ P. 203ˆ

The Preston tube as a means of measuring skin friction

1962 ◽  
Vol 14 (1) ◽  
pp. 1-17 ◽  
Author(s):  
M. R. Head ◽  
I. Rechenberg
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Skin Friction ◽  
Pipe Flow ◽  
Large Diameter ◽  
Turbulent Pipe Flow ◽  
Pitot Tube ◽  
Diameter Pipe ◽  
Flow Similarity ◽  
Considerable Doubt

Preston's method of measuring skin friction, which makes use of a Pitot tube resting on the surface, depends upon the assumption of a region of flow similarity, adjacent to the wall, common to fully developed turbulent pipe flow and the turbulent boundary layer. Experiments performed elsewhere have cast considerable doubt on the validity of this assumption, and the present investigation was undertaken to establish whether or not it is justified.Experiments were carried out in a short length of large-diameter pipe which could either form part of a very much longer pipe, giving fully developed turbulent pipe flow, or could be preceded by a conventional contraction and screens, giving a developing turbulent boundary layer.Final results showed that for a given skin friction the Pitot tube reading was the same for both boundary layer and pipe flows, thus vindicating Preston's method and confirming the existence of a universal region of wall similarity. Initial experimental difficulties were found to be due to unexpectedly large circumferential variations in skin friction in the growing boundary layer.

Further Experiments With Suction at a Sudden Enlargement in a Pipe

1970 ◽  
Vol 92 (3) ◽  
pp. 437-447 ◽  
Author(s):  
Gunnar Heskestad
Keyword(s):  
Boundary Layer ◽  
Pipe Flow ◽  
Expansion Ratio ◽  
Turbulent Pipe Flow ◽  
Thin Boundary Layer ◽  
Inlet Flow ◽  
Upper Limit ◽  
Sudden Enlargement ◽  
Flow Through ◽  
And Performance

Previously reported experiments on incompressible flow through a step expansion in a pipe, as influenced by suction at the smaller diameter of the step, have been extended to examine effects of inlet flow on suction requirements and performance of the device as a (short) diffuser. Here the performance for a fully developed turbulent pipe flow is considered and compared to previous results for an inlet flow with thin boundary layer. Whenever overall diffuser length is restricted to values less than some upper limit for a given expansion ratio, then for either inlet flow condition, the present device is shown to produce higher pressure recoveries (adjusted for suction power) than conical diffusers.

Deposition Process and Equivalent Markov Motion of High-inertia Particles in a Long Straight Pipeline

2021 ◽  
Author(s):  
Ri Zhang ◽  
Kai Xu ◽  
Yong Liu ◽  
Yumiao Wang
Keyword(s):  
Boundary Layer ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Pipe Flow ◽  
Particle Deposition ◽  
Deposition Velocity ◽  
Deposition Process ◽  
Turbulent Pipe Flow ◽  
Probability Density Distribution ◽  
The Monte Carlo Method

Abstract Two methods are used to study the process of particle deposition in a turbulent pipe flow. The Monte Carlo method tracks 10,000 particles in the turbulent pipe flow to reproduce the deposition process of the particles. The deposition velocity of the particles is determined by calculating the proportion of particles passing through the test section. The simplified deposition model uses an equivalent Markov motion instead of the radial movement of the particle in the turbulent core. The probability that a particle leaves the turbulent core depends on the radial particle position and the probability density distribution of the random vortex. The probability that a particle penetrates the boundary layer can be solved by integrating the probability density distribution of radial particle velocity. The deposition velocity of particles can be obtained by calculating the probability of an individual particle leaving the turbulent core and penetrating the boundary layer. Five experimental data series from the literature are applied to examine the predictive abilities of the two methods. The results demonstrate that the Monte Carlo method can be properly used to track the particle deposition process in the diffusion-impaction and inertia-moderated regimes. The simplified model is suitable for high-inertia particles.

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