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Pipe flow

About: Pipe flow is a research topic. Over the lifetime, 13826 publications have been published within this topic receiving 351605 citations.


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TL;DR: In this article, the stability of these steady flows to small time-dependent perturbations is determined, and it is shown that the tube may be unstable to at least three different modes of oscillation, with frequencies in distinct bands, depending on the governing parameters.
Abstract: In a previous paper (Jensen & Pedley 1989) a model was analysed describing the effects of longitudinal wall tension and energy loss through flow separation on the existence and nature of steady flow in a finite length of externally pressurized, elastic-walled tube. The stability of these steady flows to small time-dependent perturbations is now determined. A linear analysis shows that the tube may be unstable to at least three different modes of oscillation, with frequencies in distinct bands, depending on the governing parameters ; neutral stability curves for each mode are calculated. The motion of the separation point at a constriction in the tube appears to play an important role in the mechanism of these oscillations. A weakly nonlinear analysis is used to examine the instabilities in a neighbourhood of their neutral curves and to investigate mode interactions. The existence of multiple independent oscillations indicates that very complex dynamical behaviour may occur.

86 citations

Journal ArticleDOI
TL;DR: In this paper, a detailed study of pipe flow relative periodic orbits with energies and mean dissipations close to turbulent values is performed, and several approaches to reduce the translational symmetry of the system are outlined.
Abstract: The chaotic dynamics of low-dimensional systems, such as Lorenz or Rossler flows, is guided by the infinity of periodic orbits embedded in their strange attractors. Whether this is also the case for the infinite-dimensional dynamics of Navier–Stokes equations has long been speculated, and is a topic of ongoing study. Periodic and relative periodic solutions have been shown to be involved in transitions to turbulence. Their relevance to turbulent dynamics – specifically, whether periodic orbits play the same role in high-dimensional nonlinear systems like the Navier–Stokes equations as they do in lower-dimensional systems – is the focus of the present investigation. We perform here a detailed study of pipe flow relative periodic orbits with energies and mean dissipations close to turbulent values. We outline several approaches to reduction of the translational symmetry of the system. We study pipe flow in a minimal computational cell at , and report a library of invariant solutions found with the aid of the method of slices. Detailed study of the unstable manifolds of a sample of these solutions is consistent with the picture that relative periodic orbits are embedded in the chaotic saddle and that they guide the turbulent dynamics.

86 citations

Journal ArticleDOI
TL;DR: In this paper, a high-pressure tube viscometer was used to evaluate the flow properties of water-based and oil-based hydrate slurries under laminar and turbulent pipe flow conditions.
Abstract: Natural gas hydrates have been proposed as a means to capture associated gas produced on offshore oil platforms. Hydrates are produced by bringing the gas into contact with liquid water, resulting in a hydrate-in-water slurry. It is further suggested that the hydrates be mixed with the crude oil, resulting in an hydrate-in-oil slurry that might be transported to shore in shuttle tankers, or in long-distance pipelines. A hydrate laboratory has been built to obtain the data necessary to evaluate such processes. The laboratory contains a high-pressure tube viscometer in which the flow properties of water-based and oil-based hydrate slurries can be studied under laminar and turbulent pipe flow conditions. In this paper, the experimental equipment is described, and experiments on the flow properties of hydrate-in-water slurries are presented. It was found that the slurry viscosity increases with increasing hydrate concentration, and also that the hydrate slurries approach the same frictional pressure drop as the carrying water in the turbulent flow regime, regardless of hydrate concentration.

85 citations

Journal ArticleDOI
TL;DR: In this paper, the flow of a periodic suspension of two-dimensional viscous drops between two parallel plane walls is considered, and a framework for performing dynamic simulations with suspensions of increasingly complex structure is developed.
Abstract: The flow of a periodic suspension of two‐dimensional viscous drops between two parallel plane walls is considered, and a framework for performing dynamic simulations with suspensions of increasingly complex structure is developed. The computations are based on an improved implementation of the boundary integral method which is coined the method of interfacial dynamics. An elementary configuration is considered in detail in which the suspension is composed of a periodic array of suspended drops arranged on a single file, and the flow is driven by the relative motion of the two walls. The motion is studied as a function of the capillary number, the viscosities of the fluids, and the drop size. The transition from the small‐drop behavior, where the effects of the walls are insignificant, to the large‐drop behavior, where the drops occupy almost the whole of the clearance between the walls, is illustrated. It is found that, in all cases, the suspension exhibits a shear‐thinning behavior and some type of elasticity. The single‐file arrangement is unstable to subharmonic perturbations in which the drops are displaced in an alternating fashion across the centerline of the channel. The evolution of the perturbed array may lead to oscillatory motions including orbiting and bypassing, or to formation of a double file of nearly stationary drops. The effects of drop interactions on the effective properties of the suspension are discussed.

85 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202335
202275
2021170
2020177
2019273
2018281