Abstract
The flow through pipe bends and elbows occurs in a wide range of applications. While many experimental data are available for such flows in the literature, their numerical simulation is less abundant. Here, we present highly-resolved simulations of laminar and turbulent water flow in a 90° pipe bend using Smoothed Particle Hydrodynamics (SPH) methods coupled to a Large-Eddy Simulation (LES) model for turbulence. Direct comparison with available experimental data is provided in terms of streamwise velocity profiles, turbulence intensity profiles and cross-sectional velocity maps at different stations upstream, inside and downstream of the pipe bend. The numerical results are in good agreement with the experimental data. In particular, maximum root-mean-square deviations from the experimental velocity profiles are always less than ∼1.4%. Convergence to the experimental measurements of the turbulent fluctuations is achieved by quadrupling the resolution necessary to guarantee convergence of the velocity profiles. At such resolution, the deviations from the experimental data are ∼0.8%. In addition, the cross-sectional velocity maps inside and downstream of the bend shows that the experimentally observed details of the secondary flow are also very well predicted by the numerical simulations.
Highlights
Pipe bends and elbows are frequently used to fit pipeline systems
We present the results of highly resolved Smoothed Particle Hydrodynamics (SPH) simulations of laserDoppler velocimetry measurements of laminar and developing turbulent water flow in a 90◦ pipe elbow reported by Enayet et al [1]
The laminar and turbulent flows of water through a 90◦ pipe bend were simulated numerically using Smoothed Particle Hydrodynamics (SPH) techniques coupled to a largeeddy simulation (LES) approach and non-reflective outflow boundary conditions at the pipe exit
Summary
Pipe bends and elbows are frequently used to fit pipeline systems. They are important in many engineering applications such as the transportation of oil and gas in pipelines as well as other fluids, including hot water and steam for shorter distances, water for drinking or irrigation over long distances and hydrogen from the point of delivery to the point of demand, just to mention a few applications. Du et al [18] employed a LES turbulence model together with the proper orthogonal decomposition method to investigate the effects of varying the bend angle on pressure drop and mean flow characteristics in a small-diameter corrugated pipe. The few examples found in the literature include the twodimensional simulations by Hou et al [19], who studied flow separation in right-angled bends for different turning angles; the three-dimensional SPH simulations by AlvaradoRodríguez et al [20], where the numerical results were compared with Sudo et al.’s [2] experimental measurements for turbulent flow in a square-sectioned 90◦ pipe bend and Rup et al.’s [6] Fluent-based simulations of Sudo et al.’s experiment; and the calculations by Rosicet al. This enforces the incompressibility condition because the effects of any compression induced by such density fluctuations will be purely acoustic and superimposed to the main flow with almost no interaction
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