Fig. 1. Oblique view of the Large-scale Sediment Transport Facility Zregular wave experiment

Hamilton_Ebersole_ce_2001
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current magnitudes and cross-shore distributions to

downstream-directed longshore current speeds and

be accurately controlled and externally recirculated.

flow rates presented in the paper are given as posi-

Hamilton et al. Z1997. provides design details for

tive numbers, even though the flow is in the negative

each of the primary components in the recirculation

y direction.

system.

The external recirculation system consists of 20

Design of the upstream and downstream lateral

independent pump-and-piping systems with a total

boundaries was a challenge since the longshore cur-

capacity of 1250 lrs. Hamilton et al. Z1996. describe

rent has to flow out of and into the flow channels

the methodology used to determine the capacity and

while wave diffraction into the flow channels needs

functional requirements of this system. Twenty flow

to be minimized. Waveguides were designed so that

channels at the downstream end of the facility guide

the height of the opening beneath the waveguide

the longshore current from the beach to the pumps

could be adjusted to allow the longshore current to

Zsee Fig. 2.. Likewise, on the upstream end, 20 flow

pass beneath the impermeable waveguide. For the

channels guide the flow from the point of pipe

wave conditions and water level used during these

discharge to the upstream boundary of the beach.

experiments, the height of the opening was selected

Flow channels extend from x s 3.0 to 18.0 m in the

after several trial and error iterations. At the up-

cross-shore direction, and each channel is 0.75 m

stream boundary a constant 0.1-m high opening be-