Velocity profiles at the swash zone have been sampled with an ADVP during a large scale experiment on a fixed bed beach. The unique set of data permits to observe the time variation of the velocity distributions and to contribute to the debate concerning the variation of the friction factor, f, in a swash cycle. The analyses of the velocity data with the ballistic model and with the Law of the Wall have given opposite results. It is shown that if the pressure gradient is considered, the friction factor is expected to be larger at uprush than at downrush. Finally, for the adopted beach characteristics and at transects above the still water level shoreline, it is assumed f =0.016 at the uprush, and f = 0.009 at the downrush.
Velocity profiles at the swash zone
FREGA, Ferdinando
2003-01-01
Abstract
Velocity profiles at the swash zone have been sampled with an ADVP during a large scale experiment on a fixed bed beach. The unique set of data permits to observe the time variation of the velocity distributions and to contribute to the debate concerning the variation of the friction factor, f, in a swash cycle. The analyses of the velocity data with the ballistic model and with the Law of the Wall have given opposite results. It is shown that if the pressure gradient is considered, the friction factor is expected to be larger at uprush than at downrush. Finally, for the adopted beach characteristics and at transects above the still water level shoreline, it is assumed f =0.016 at the uprush, and f = 0.009 at the downrush.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
