Abstract
The wave reflection from a single-chamber porous vertical wall wave absorber system is examined. For monochromatic, long-crested, small amplitude waves impinging upon and with normal incidence to a porous wall, a theoretical solution for the reflection coefficient is determined based on the approach of Fugazza and Natale (1992). The effects of both wave and absorber characteristics on the theoretical model are studied. Experiments are conducted in a wave tank to measure the reflection coefficient for various wave periods, wave heights, and porosities as well as for different water depths. Three different measurement techniques are employed and compared. These techniques are the single stationary probe method, the single moveable probe method, and the five probe method. The contraction coefficient, discussed in the theoretical development, is chosen based on previous research and not examined during the experimental procedures. The experimental results are then compared to the theoretical modells predictions. The results show that the single stationary probe method, along with being the simplest to employ, yields results that most closely match the theoretical prediction. The moveable probe method yields experimental results having only fair agreement with theory. The results of the five probe method are erratic and are inconsistent with both the theoretical results and the other measurement methods. There is no one porosity that yields the best agreement with theory for all measurement methods. A wave height between 0.12 feet and 0.14 feet consistently yields the best agreement between the experimental results and the theoretical prediction for all methods. Finally, increasing the water depth improves agreement between theoretical predictions and experimental results for all measurement techniques.
Hagan, Christine L. (1994). A theoretical/experimental study of the design of a porous wave absorber system. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1994 -THESIS -H141.