Topic
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: The linearized NavierStokes equations play a central role in describing the unsteady motion of a viscous fluid inside a porous tube and asymptotic solutions of these equations have been found.
Abstract: The linearized NavierStokes equations play a central role in describing the unsteady motion of a viscous fluid inside a porous tube. Asymptotic solutions of these equations have been found and here...
107 citations
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TL;DR: In this article, the authors used the CFD software OpenFOAM to simulate the turbulent flow in pipes with elbow and compared the results with the LDA (Laser Doppler anemometer) measurements from the experiments currently conducted to find the dependency of the flows on the Reynolds number.
Abstract: The purpose of this study is to characterize the swirling secondary flow in the downstream of a pipe bend using a numerical simulation of the flow. The CFD (Computational Fluid Dynamics) software OpenFOAM is used to simulate the turbulent flow in pipes with elbow. Various turbulence models are benchmarked with the existing experimental data and a comparative study is performed to select an appropriate turbulence model for the analysis. Predictions made by the selected turbulence model are compared with the LDA (Laser Doppler anemometer) measurements from the experiments currently conducted to find the dependency of the flows on the Reynolds number. It is found that the swirl intensity of the secondary flow is a strong function of the radius of curvature of the bend and a weak function of the Reynolds number. Additionally, it is found that the dissipation of the swirl intensity is exponential in nature.
107 citations
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TL;DR: In this paper, the interfacial behavior during air-kerosene stratified-wavy flow in a 77.9mm-dia 420m-long pipeline was observed carefully.
Abstract: Gas-liquid stratified-wavy flow with low liquid loading is common in natural gas transmission pipelines and offshore gas pipelines. This specific case of two-phase pipe flow has been studied experimentally and theoretically in the present paper. The interfacial behavior during air-kerosene stratified-wavy flow in a 77.9-mm-dia 420-m-long pipeline was observed carefully. The gas-liquid interface usually exhibits a concave downward curved configuration. The liquid film-wetted wall fraction, liquid holdup, and pressure drop were also measured. A mechanistic double-circle model and a correlation for interfacial friction factor, required as a closure relationship in the model, have been developed. The new model gives significantly improved predictions for both liquid holdup and pressure drop during gas-liquid stratified-wavy flow in horizontal pipelines.
107 citations
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TL;DR: In this paper, a 2 + ∈-dimensional model of pipe flow is introduced, which is a minimal three-dimensionalization of the axisymmetric case: only sinusoidal variation in azimuth plus azímuthal shifts are retained; yet the same dynamics familiar from experiments are found.
Abstract: Fully three-dimensional computations of flow through a long pipe demand a huge number of degrees of freedom, making it very expensive to explore parameter space and difficult to isolate the structure of the underlying dynamics. We therefore introduce a '2 + ∈-dimensional' model of pipe flow, which is a minimal three-dimensionalization of the axisymmetric case: only sinusoidal variation in azimuth plus azimuthal shifts are retained; yet the same dynamics familiar from experiments are found. In particular the model retains the subcritical dynamics of fully resolved pipe flow, capturing realistic localized 'puff-like' structures which can decay abruptly after long times, as well as global 'slug' turbulence. Relaminarization statistics of puffs reproduce the memoryless feature of pipe flow and indicate the existence of a Reynolds number about which lifetimes diverge rapidly, provided that the pipe is sufficiently long. Exponential divergence of the lifetime is prevalent in shorter periodic domains. In a short pipe, exact travelling-wave solutions are found near flow trajectories on the boundary between laminar and turbulent flow. In a long pipe, the attracting state on the laminar-turbulent boundary is a localized structure which resembles a smoothened puff. This 'edge' state remains localized even for Reynolds numbers at which the turbulent state is global.
107 citations
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TL;DR: In this article, the authors define a measure of chaos for open flow systems driven by low-level external noise: the time-dependent generalized Ginzburg-Landau equation and a system of coupled logistic maps.
107 citations