Bedform dynamics from coupled bed-flow direct numerical simulations

N Zgheib,S Balachandar,M.M Perillo,J.J Fedele,D.C.J.D Hoyal,N Moubayed

doi:10.1051/matecconf/201926103001

Abstract

We present results of time-evolving coupled direct numerical simulations between an erodible bed and an overlying pressure-driven, turbulent flow field. A total of 6 simulations are considered, the details of which are shown in Table 1. The numerical setup consists of a horizontally periodic open channel, and the simulations are run at a shear Reynolds number of Reτ = 180. The coupling between the spatially and temporally evolving sediment bed and the flow field is enforced through the explicit immersed boundary method (IBM) of Uhlmann [1]. The flow field is fully resolved and is obtained by integrating the conservation of mass and momentum equations using a pseudo spectral code [2]. On the other hand, the sediment bed is modelled via the Exner equation [3]. Details about the numerical approach are available in [4-5].

Highlights

Ripples are examples of bedform patterns that result from the instability of an erodible bed of particles subjected to the shearing action of an overlying flow field [6]
The Chevron features are next to emerge in panel c followed by the incipient crestlines in panel d
There is a rich spectrum of bedform interactions that occur during the development of the bed. [7] provide a thorough summary of the various bedform interactions documented in laboratory experiments as well as field studies

Summary

Introduction

Ripples are examples of bedform patterns that result from the instability of an erodible bed of particles subjected to the shearing action of an overlying flow field [6]. 1 Background Ripples are examples of bedform patterns that result from the instability of an erodible bed of particles subjected to the shearing action of an overlying flow field [6]. The evolution of ripples has been well documented experimentally and numerically. We show using coupled, flow-bed simulations that we are able to capture the various stages of ripple formation observed in experimental flumes.

Results

Conclusion