Numerical investigation of unsteady effects in oscillatory sheet flows

Mathieu, Antoine
Cheng, Zhen
Chauchat, Julien
Bonamy, Cyrille
Hsu, Tian-Jian
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Journal of Fluid Mechanics
In this paper, two-phase flow simulations of oscillatory sheet flow experimental configurations involving medium and fine sand using a turbulence-resolving two-fluid model are presented. The turbulence-resolving two-phase flow model reproduces the differences of behaviour observed between medium and fine sand whereas turbulence-averaged models require an almost systematic tuning of empirical model coefficients for turbulence–particle interactions. The two-fluid model explicitly resolves these interactions and can be used to study in detail the differences observed experimentally. Detailed analysis of concentration profiles, flow hydrodynamics, turbulent statistics and vertical mass balance allowed the confirmation that unsteady effects, namely phase-lag effect and enhanced boundary layer thickness, for fine sand are not only due to the small settling velocity of the particles relative to the wave period. The occurrence and intensity of unsteady effects are also affected by a complex interplay between flow instabilities, strong solid-phase Reynolds stress and turbulence attenuation caused by the presence of the particles.
This is an Accepted Manuscript version of an article originally published in Journal of Fluid Mechanics. The version of record is available at: This version is free to view and download for private research and study only. Not for re-distribution or re-use. © The Author(s), 2022. Published by Cambridge University Press. This article will be embargoed until 12/06/2022.
sediment transport , particle/fluid flow , turbulent boundary layers
Mathieu, A., Cheng, Z., Chauchat, J., Bonamy, C., & Hsu, T. (2022). Numerical investigation of unsteady effects in oscillatory sheet flows. Journal of Fluid Mechanics, 943, A7. doi:10.1017/jfm.2022.405