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arXiv · 1405.5125

Direct numerical simulation of pattern formation in subaqueous sediment

Aman G. Kidanemariam·Markus Uhlmann
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Abstract

We present results of direct numerical simulation of incompressible fluid flow over a thick bed of mobile, spherically-shaped particles. The algorithm is based upon the immersed boundary technique for fluid-solid coupling and uses a soft-sphere model for the solid-solid contact. Two parameter points in the laminar flow regime are chosen, leading to the emergence of sediment patterns classified as `small dunes', while one case under turbulent flow conditions leads to `vortex dunes' with significant flow separation on the lee side. Wavelength, amplitude and propagation speed of the patterns extracted from the spanwise-averaged fluid-bed interface are found to be consistent with available experimental data. The particle transport rates are well represented by available empirical models for flow over a plane sediment bed in both the laminar and the turbulent regimes.

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Aman G. Kidanemariam, Markus Uhlmann. 2014-05-20. Direct numerical simulation of pattern formation in subaqueous sediment. https://doi.org/10.1017/jfm.2014.284

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