The present study focuses at improving our basic understanding of sizegraded sand transport mechanisms under oscillatory sheet-flow conditions using different transport models. Moreover, the study aims at improving the performance of different transport model concepts for the description of both the rate and sizecomposition of the transported sand. Quasi-steady and intermediate models are investigated, in combination with a large dataset of oscillatory sediment transport measurements (sheet-flow conditions) as collected from two oscillatory water tunnels. A comparison is made between the measured net transport rates and transport rates per size fraction and the results from various transport formulas (Bailard 1981; Ribberink 1998; Dibajnia & Watanabe 1996; Dohmen-Janssen et al., 2002). First, the comparison is based on a 1-fraction approach I.e. the sand is modeled using D50 of the mixture. Second, a size-fraction approach is tested and developed further using the experimental dataset. Exposure corrections are proposed for fine and coarse size fractions in the sand mixture to improve model performance.
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