The time-dependent drag on naturally rippled sand beds under oscillatory flows is measured in laboratory experiments. The time integral of the product of this drag and the oscillatory flow velocity provide the energy dissipated per period. A positive displacement oscillatory flow tunnel provides amplitudes and periods of flow over a wide range of prototype conditions. With the test section split longitudinally into two channels, one containing the sand bed and the other having a smooth metallic bottom, the drag on the bed is obtained from the measured difference between pressure gradients in the two channels. Two sands are used, with diameters 0.55 and 0.18 mm. The experimental profiles are mostly natural and mature, but some are deliberately distorted. Others are in process of growth from a bed initially flat.
Drag on naturally rippled beds under oscillatory flows
Miscellaneous Paper ; CERC-86-13
1986
4585430
Report
Elektronische Ressource
Englisch
Seabed , Laboratory , Drag , Measurement , Dissipation , Ripple , Stress , Oscillatory , Time-dependent , Sand , Unsteady
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