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High-Strouhal-number pulsatile flow in a curved pipe

Published online by Cambridge University Press:  27 July 2021

Feroz Ahmed*
Affiliation:
Centre for Engineering in Extreme Environments, University College London, Torrington Place, London WC1E 7JE, UK
Ian Eames
Affiliation:
Centre for Engineering in Extreme Environments, University College London, Torrington Place, London WC1E 7JE, UK
Emad Moeendarbary
Affiliation:
Mechanics in Biology & Medicine Group (MecBioMed), Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
Alireza Azarbadegan
Affiliation:
BP Exploration Operating Company Limited, Chertsey Road, Sunbury-on-Thames, Middlesex TW16 7NL, UK
*
Email address for correspondence: ucemfah@ucl.ac.uk

Abstract

The high-Strouhal-number pulsatile flow in a curved pipe is studied numerically. A general force analysis is developed for the bend force, where the new contribution from flow acceleration is identified and analysed. The mechanisms of secondary flow production are studied by extending Hawthorne's (Proc. R. Soc. Lond. A, vol. 206, issue 1086, 1951, pp. 374–387) model to account for viscous effects and applied to assess the distinct contributions from an inviscid stretching and no-slip condition. A detailed comparison is made between the numerical simulations and models for a pipe flow characterised by a volume flux $Q=U_b A |\sin \varOmega _p t|$ (where $U_b$ is the maximum bulk velocity, $\varOmega _p$ is the angular frequency and $A$ is the pipe cross-sectional area). For high-Reynolds-number ($Re_b$) and high-Strouhal-number ($St$), the bend force predictions are in good agreement with the numerical results over a wide range of bend curvature ($R_c/D$; where $R_c$ is the bend radius of curvature and $D$ is the pipe diameter) owing to the influence of the streamwise flow acceleration on the pressure field. At high-$St$, the streamwise vorticity (secondary flow) distribution is steady and close to the low-$St$ case, which is explained using a linear secondary flow model.

Information

Type
JFM Papers
Copyright
© The Author(s), 2021. Published by Cambridge University Press

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