Evolution of turbulence characteristics from straight to curved pipes

Noorani, Azad; Khoury, George K. El; Schlatter, Philipp

doi:10.1016/j.ijheatfluidflow.2013.03.005

Cited by 87 publications

(57 citation statements)

References 25 publications

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“…b Schematic picture of a general section of a curved pipe, with locations of the crosssections (θ = 0 as horizontal line, and θ = π/2 as vertical/equatorial mid-plane). c Side view of the curved pipe geometry and associated coordinate systems, (X, Y, Z) as reference Cartesian coordinates and (R, s, ζ ) as attached toroidal coordinate system to those used by Noorani et al [16] for the unladen simulations at the highest Reynolds number. The bulk Reynolds number is fixed to 11700 for both the mildly curved pipe (κ = 0.01) and the strongly curved pipe (κ = 0.1), which ensures that the flow remains turbulent in both cases.…”

Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

“…The overbar in u τ denotes an average along the circumference of the pipe section. Further details on the statistical averaging pertaining the carrier phase via tensor transformations under rotation from Cartesian coordinates to toroidal/poloidal coordinates are given in Noorani et al [16]. The verification of the method together with the validation of the simulation set-up are also presented there.…”

Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

“…In these studies the effect of the curvature on the mean flow and velocity fluctuations is studied for low curvatures. In the recent work by Noorani et al [16] DNSs are performed in sufficiently long pipes at moderately high Reynolds numbers such that the flow remains turbulent even in strongly curved configurations. The Reynolds stress budgets are computed for various curvatures and it is shown that the turbulent flow is highly damped in the inner side of the strongly curved pipe while it remains fully turbulent in the outer bend.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Particle Velocity and Acceleration in Turbulent Bent Pipe Flows

Noorani

Sardina

Brandt

et al. 2015

Flow Turbulence Combust

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We study the dynamics of dilute micro-size inertial particles in turbulent curved pipe flows of different curvature by means of direct numerical simulations with one-way coupled Lagrangian particle tracking. The focus of this work is on the first and second order moments of the velocity and acceleration of the particulate phase, relevant statistics for any modelling effort, whereas the particle distribution is analysed in a previous companion paper. The aim is to understand the role of the cross-stream secondary motions (Dean vortices) on the particle dynamics. We identify the mean Dean vortices associated to the motion of the particles and show that these are moved towards the side-walls and, interestingly, more intense than those of the mean flow. Analysis of the streamwise particle flux reveals a substantial increase due to the secondary motions that brings particles towards the pipe core while moving them towards the outer bend. The in-plane particle flux, most intense in the flow viscous sub-layer along the side walls, increases with particle inertia and pipe curvature. The particle reflections at the outer bend, previously observed also in other strongly curved configurations, locally alter the particle axial and wall-normal velocity and increase turbulent kinetic energy.

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Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

Section: Governing Equations and Numerical Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Particle Velocity and Acceleration in Turbulent Bent Pipe Flows

Noorani

Sardina

Brandt

et al. 2015

Flow Turbulence Combust

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“…They illustrated the effect of the retardation ratio and the extensibility on the velocity distribution and development. Noorani et al 20 obtained the characteristics such as fluctuations, Reynolds stress budgets for turbulent flow in both straight and curved pipes using DNSs. Amicis et al 12 illustrated differences among various numerical codes (FLUENT, OpenFOAM, and COMSOL) when they were applied to describe the effect of geometry on coiled pipe flow.…”

Section: Introductionmentioning

confidence: 99%

A numerical study of flow characteristics in a helical pipe

Tang

Parameswaran

2016

Advances in Mechanical Engineering

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Flow characteristics and loss mechanism inside the helical pipe with large-caliber and large-scale Dean number were analyzed in this study. Numerical simulation was carried out for exploring velocity distribution, pressure field, and secondary flow by varying coil parameters such as Dean number, curvature radius, and coil pitch. The velocity gradient in the cross-section increases along the pipe and causes unsteady flow in the pipe. Large pressure differences in the 180°and 315°cross-section generate centrifugal forces on the pipe. The secondary flow is the major factor resulting in flow loss, presented obviously by the streamlines to analyze the effects of pipe parameters on the vortices. The vortex center shifts toward the upper wall with the increase in Dean number and takes a slight deflection with the increase in coil pitch. Meanwhile, a correlation of the flow loss extent inside the pipe as a function of friction factor was presented. The increases in curvature radius and coil pitch can diminish the friction factor to reduce flow losses. The accuracy of the numerical methodology was also validated by conducting corresponding experiments and empirical mathematical analysis. The maximum deviation between the experimental values and the simulated results of the pressure drop is just 2.9%.

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“…They also found that the torsion affected the critical Reynolds number and destabilized the flow. Noorani et al 21 and Jayakumar et al 22 numerically studied the effects of coil parameters on the nature of turbulence flow and obtained the higher-order effect. Hu¨ttl and Friedrich 23,24 carried out research on various pipe parameters by means of direct numerical simulation.…”

mentioning

confidence: 99%

Secondary vortex-based analysis of flow characteristics and pressure drop in helically coiled pipe

Tang

Yuan

Malin

et al. 2017

Advances in Mechanical Engineering

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This article presents an investigation for the secondary flow characteristics and associated pressure loss in fluid flow through helically coiled pipe. Computational fluid dynamics is employed to analyze the pipe flow with various geometries, and the accuracy of the numerical methodology is validated by conducting corresponding experiments. The analysis performs a detailed parametric study involving the pressure loss, the secondary vortex motion, and the secondary vortex intensity for a range of coil diameters (D; ranging from 300 to 3000 mm) and pipe diameters (d; ranging from 50 to 90 mm). The pipe flow develops to a stable state with increase in coil diameter, while an increase in pipe diameter delays this development. Then, the secondary flow characteristics are analyzed to explore the pressure loss mechanism. The distorted streamline of secondary vortices and the enlarged deflection angle of secondary vortices are both factors contributing to the enhanced pressure loss. Furthermore, the effects of pipe flow development on the following flow characteristics such as the turbulence dissipation rate and the secondary vortex intensity are revealed. These characteristics all distribute regularly and reach lower values when pipe flow begins to a stable state.

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Evolution of turbulence characteristics from straight to curved pipes

Cited by 87 publications

References 25 publications

Particle Velocity and Acceleration in Turbulent Bent Pipe Flows

Particle Velocity and Acceleration in Turbulent Bent Pipe Flows

A numerical study of flow characteristics in a helical pipe

Secondary vortex-based analysis of flow characteristics and pressure drop in helically coiled pipe

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