Threshold studies of gravel size particles under the co-linear combined action of waves and currents |
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Authors: | I PANAGIOTOPOULOS G SYLAIOS M B COLLINS |
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Institution: | Oceanography Department, The University, Southampton SO171BJ, UK |
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Abstract: | Gravel size sediment beds are tested under the combined influence of simulated wave action and co-linear currents in a laboratory flume. Critical current speed, at threshold, increases with increasing size. Superimposed wave energy causes a small reduction in the unidirectional current energy. For low values of wave-induced near bed current velocities, the resistance to erosion increases when the wave period decreases from 10 to 6 s. Finally, combined critical shear stresses are found to be lower than those predicted using the Shields curve, as modified for oscillatory flow. Grain protrusion is suggested as a mechanism to explain this divergence. |
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