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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 paper, the authors studied the flow of an incompressible, thermodynamically compatible fluid of grade three in a pipe, where the temperature of the pipe is assumed to be higher than that of the fluid, and the shear viscosity of the liquid was modeled as a function of the temperature.
Abstract: The flow of a fluid-solid mixture is very complicated and may depend on many variables, such as the physical properties of each phase and the size and shape of the solid particles. One approach to the study of these flows is to model the mixture as a non-Newtonian fluid. Much effort has been put into analyzing various transport processes in non-Newtonian fluids, such as coal slurries. Heat transfer plays an important role in the handling and processing of these fluids. In this paper, the fully developed flow of an incompressible, thermodynamically compatible fluid of grade three in a pipe is studied. The temperature of the pipe is assumed to be higher than the temperature of the fluid and the shear viscosity of the fluid is assumed to be a function of the temperature.

157 citations

Journal ArticleDOI
TL;DR: In this paper, the shape of the dominant large-scale structure is investigated by conditional averages based on the large scale velocity, determined using a filter width equal to the channel half-height.
Abstract: We investigate statistics of large-scale structures from large-eddy simulation (LES) of turbulent channel flow at friction Reynolds numbers Re_τ = 2K and 200K (where K denotes 1000). In order to capture the behaviour of large-scale structures properly, the channel length is chosen to be 96 times the channel half-height. In agreement with experiments, these large-scale structures are found to give rise to an apparent amplitude modulation of the underlying small-scale fluctuations. This effect is explained in terms of the phase relationship between the large- and small-scale activity. The shape of the dominant large-scale structure is investigated by conditional averages based on the large-scale velocity, determined using a filter width equal to the channel half-height. The conditioned field demonstrates coherence on a scale of several times the filter width, and the small-scale–large-scale relative phase difference increases away from the wall, passing through π/2 in the overlap region of the mean velocity before approaching π further from the wall. We also found that, near the wall, the convection velocity of the large scales departs slightly, but unequivocally, from the mean velocity.

157 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the effect of micropolar fluid material parameters on the distribution of velocity, micro-rotation velocity and temperature fields for varying physical parameters such as the ratio of Grashof number to Reynolds number, viscosity ratio, width ratio, conductivity ratio and micropolastic fluid material parameter.

156 citations

Journal ArticleDOI
TL;DR: The main goal of this article is to review various results and methods concerning the numerical simulation of Bingham visco-plastic flow; these results have been obtained from the early 1970s to now.
Abstract: The main goal of this article is to review various results and methods concerning the numerical simulation of Bingham visco-plastic flow; these results have been obtained from the early 1970s to now. We consider first the case of flow in cylindrical pipes and then flow in multi-dimensional cavities. The methods to be discussed include classical ones relying on regularization, (kind of) Lagrange multipliers and augmented Lagrangian techniques; they include also a duality–penalty method whose implementation relies on a Newton-Conjugate Gradient-Uzawa algorithm which seems to be new (in this context at least). Other issues are addressed; they concern particularly the accelerated calculation of steady state solutions and the time discretization of the unsteady flow models. The results of numerical experiments are presented, including the simulation of the wall driven flow in square cavities.

156 citations

Journal ArticleDOI
TL;DR: In this paper, a three-dimensional simulation of the step geometry for 100 ⩽ Re⩽ 800 and correctly predicts the primary reattachment lengths, thus confirming the influence of three dimensionality.
Abstract: A numerical investigation of laminar flow over a three-dimensional backward-facing step is presented with comparisons with detailed experimental data, available in the literature, serving to validate the numerical results. The continuity constraint method, implemented via a finite element weak statement, was employed to solve the unsteady three-dimensional Navier–Stokes equations for incompressible laminar isothermal flow. Two-dimensional numerical simulations of this step geometry underestimate the experimentally determined extent of the primary separation region for Reynolds numbers Re greater than 400. It has been postulated that this disagreement between physical and computational experiments is due to the onset of three-dimensional flow near Re ≈ 400. This paper presents a full three-dimensional simulation of the step geometry for 100⩽ Re⩽ 800 and correctly predicts the primary reattachment lengths, thus confirming the influence of three-dimensionality. Previous numerical studies have discussed possible instability modes which could induce a sudden onset of three-dimensional flow at certain critical Reynolds numbers. The current study explores the influence of the sidewall on the development of three-dimensional flow for Re greater than 400. Of particular interest is the characterization of three-dimensional vortices in the primary separation region immediately downstream of the step. The complex interaction of a wall jet, located at the step plane near the sidewall, with the mainstream flow reveals a mechanism for the increasing penetration (with increasing Reynolds number) of three-dimensional flow structures into a region of essentially two-dimensional flow near the midplane of the channel. The character and extent of the sidewall-induced flow are investigated for 100⩽Re⩽ 800. © 1997 John Wiley & Sons, Ltd.

156 citations


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