The removal of sediment deposits from a fixed bed has large implications in sewer and open channel design. Large modifications in flow field and bottom stress may be determined by the presence of the sediment deposit itself for the abrupt change of the bed level and roughness. If velocity profiles within the internal boundary layer determined by the boundary variation have been modeled with log-law, the presence of a sudden peak in shear velocity downstream the bed change is observed, the so-called overshooting. In order to assess the relevance of overshooting on sediment removal, specific experiments have been addressed on the flow field modification and on the related sediment erosion. The results of such experiments are discussed and a comparison has been performed between the critical shear velocities for sediment motion and overshooting shear velocity values.
SEDIMENT EROSION AT AN UPSTANDING STEP CHANGE IN BED LEVEL
DELLA MORTE, Renata
2007-01-01
Abstract
The removal of sediment deposits from a fixed bed has large implications in sewer and open channel design. Large modifications in flow field and bottom stress may be determined by the presence of the sediment deposit itself for the abrupt change of the bed level and roughness. If velocity profiles within the internal boundary layer determined by the boundary variation have been modeled with log-law, the presence of a sudden peak in shear velocity downstream the bed change is observed, the so-called overshooting. In order to assess the relevance of overshooting on sediment removal, specific experiments have been addressed on the flow field modification and on the related sediment erosion. The results of such experiments are discussed and a comparison has been performed between the critical shear velocities for sediment motion and overshooting shear velocity values.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
