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Title: Laboratory study on macro-features of wave breaking over bars and artificial reefs
Authors: Mississippi State University. Department of Civil Engineering.
Smith, Ernest R.
Kraus, Nicholas C.
Keywords: Breaking waves
Wave breaker type
Wave plunge distance
Laboratory study
Wave breaker vortex
Wave reflection
Wave breaker index
Wave height decay
Wave runup
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; CERC-90-12.
Description: Technical report
Abstract: A laboratory experiment was conducted in a wave tank to examine macroscale features of wave breaking over bars and reefs. Submerged triangular-shaped obstacles representing bars and reefs were installed on a 1/30 concrete slope to cause wave breaking. Seaward and shoreward slopes of the obstacles were varied, as was the deepwater wave steepness Hš—ˆ/Lš—ˆ , which resulted in 108 monochromatic wave tests and 12 irregular wave tests. Empirical expressions were determined for the wave properties investigated, which included breaker type, height, and depth; plunge, splash, and penetration distance; breaker vortex area; wave decay; wave reflection; and wave runup. Additionally, data acquired from other studies involving plane slopes were reanalyzed to determine breaker indices and plunge distance. Differences were found between wave properties on plane slopes and barred profiles, Plunging and collapsing breakers were predominate for regular waves breaking over bars and reefs, whereas spilling breakers occurred on the plane slope. The strength of return flow altered the breaking wave form. Return flow was strongest if the bars were terraced or if the seaward slope š›½ā‚ was steep, and the deepwater wave steepness Hš—ˆ/Lš—ˆ was small. The position of the break point was greatly influenced by return flow, which exerted control over the breaker depth. Breaker height was found to increase in the presence of strong return flow. Plunge distance normalized by breaking wave height was found to be shorter over irregular slopes than plane slopes. The results from the study can be used in numerical models simulating beach shoreline change and in studies of wave height decay. NOTE: This file is large. Allow your browser several minutes to download the file.
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