GRADED SEDIMENTS IN OSCILLATORY SHEET-FLOW

New experiments in the Aberdeen Oscillatory Flow Tunnel have produced a large dataset containing detailed measurements of sand transport “sub-processes” for a wide range of well-sorted and graded sands in full-scale sinusoidal and asymmetric oscillatory sheet-flow conditions. The paper concentrates on results from the sheet-flow concentration and sand transport measurements. The effects of grading are emphasised by focussing on results from 3 sand beds with the same median grain size but very different grading. Equations describing time-varying erosion depth, reference concentration and concentration profile are presented. Net sand transport results are discussed with particular attention to unsteady effects and the interaction between different size fractions in the bed.