Numerical investigation of unsteady effects in oscillatory sheet flows

Abstract

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.

Numerical investigation of mode failures in submerged granular columns

“…Simulations are conducted with the open-source software SedFoam, a two-phase flow solver used for sediment transport applications (Chassagne, Bonamy, & Chauchat, 2023; Chauchat et al, 2017; Mathieu, Chauchat, Bonamy, & Nagel, 2019; Mathieu, Cheng, Chauchat, Bonamy, & Hsu, 2022; Montellà et al, 2021; Tsai, Mathieu, Montellà, Hsu, & Chauchat, 2022) based on the open-source finite volume library OpenFOAM (Jasak & Uroić, 2020) (v2212 release from ESI). The solver is available for download from GitHub ().…”

A Bingham Plastic Fluid Solver for Turbulent Flow of Dense Muddy Sediment Mixtures

“…The interaction between this damping and the turbulent resuspension and transport of muddy sediment is not yet fully understood, but recent research has indicated a strong relationship between small scale turbulence in the bottom boundary layer and the movement of fine muddy sediment [14,15]. Two-phase modeling has been used to show that the boundary layer thickness of fine sediment suspension is increased by the complex interplay between flow instabilities, stress terms, and sediment-induced turbulence attenuation [16]. It is worthwhile to mention the processes of erosion within the context of the rheological behavior of the dense muddy mixtures.…”

Vertical dependences in swash-zone flows and sand transport

“…An example is the model by Bakhtyar et al (2010), who applied this technique to simulate small-scale swash zone dynamics under regular waves. This technique was also used by Mathieu et al (2022) for modelling detailed sediment and turbulence interactions in the sheet flow layer. Although these models include more physics, the major downside is their relative computational inefficiency.…”