Abstract
Detailed laboratory measurements of horizontal velocity above a rough, fixed, impermeable slope were made to determine the effect of varying wave conditions on the shear stress in the swash zone. The research involved the design, construction and installation of a 1:10 impermeable beach slope in a wave flume fronted by a 1:35 impermeable slope, a sidewall constricting the working section of the flume to 0.3 m, and the manufacture of a model beach for attachment onto the 1:10 slope. The 1:10 impermeable model beach comprised coarse sand of nominal diameter 2.2 mm fixed in place to ensure that the flow was fully rough turbulent. Velocities were measured at up to 18 locations along the slope using a laser Doppler velocimeter and at several elevations for each location. Free surface elevations were measured by a wave gage. The testing conditions included waves of three different periods, i.e. 2.0 s, 3.0 s and 4.0 s periods. For this thesis, two locations were assessed, one outside the surf zone and the other inside the surf zone, for 2.0 s and 4.0 s wave periods. The conclusions from the experiments were that the logarithmic profile was shown to exist over many phases of the onshore and offshore flows. Flow reversal diminished the applicability of the logarithmic profile assumption. Seaward of the surf zone, under non-breaking wave conditions, there appears to be a net onshore stress. After the wave has broken (inside the surf zone), a net offshore stress was noted. Inspection of the magnitude of the peak shear velocity for the two locations analyzed indicates that stresses were larger for longer period waves than for the shorter period waves.
Sukumaran, Ashok (2000). Laboratory measurements of the temporal and cross-shore variation of the wave-induced bed stress. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -S826.