Effect of Steepness of Regular and Irregular Waves on an Oil Containment Boom

Abstract

As part of the study described here, a mathematical model was used in an effort to predict splashover. Although the general motion of the boom can be simulated, we have a long way to go before a model will be sophisticated enough to take into account the interaction between the wave and the boom and to predict mathematically what it takes to swamp it. Introduction Shell Oil Co.'s concern with environmental pollution and more specifically the prevention of pollution of our lakes, rivers, and oceans resulted in an investigation to evaluate the effectiveness of commercial oil containment and removal devices. One phase of this extensive investigation, conducted by the Shell Pipe Line Research and Development Laboratory in Houston, was the evaluation of oil containment booms in the presence of waves. The evaluation consisted of presence of waves. The evaluation consisted of experimentally testing the commercially available booms in a wave tank; offshore testing in the Gulf of Mexico; scale model testing, at the Davidson Laboratory, Stevens Institute of Technology, Hoboken, N. J.; and attempting to mathematically model the boom response in waves. Laboratory Wave-Tank Tests The initial test phase consisted of evaluating, the performance of commercially available prototype and performance of commercially available prototype and production oil containment booms in long-crested production oil containment booms in long-crested regular waves generated in a laboratory wave tank. The wave tank built specifically for this purpose was 50 ft wide× 120 ft long and 5 ft deep, with a flapper wave generator at one end and a beach (wave absorber) at the other. This facility made it possible to generate regular waves with heights up possible to generate regular waves with heights up to 20 in. and periods ranging from 0.98 to 2.1 seconds. The following data were recorded during the wave-tank testing: wave height, wave length, wave period, the conditions at failure, and the mode of boom failure. The term "failure," of course, is subject to interpretation. Here failure relates to the operational characteristics rather than to the structural characteristics or strength of the boom and is defined as the passage of any oil either over or under the boom. The initial mode of failure for all of the booms tested was the splashing of oil over the top of the boom, with the exception of those booms that were marginally stable and that capsized without righting themselves after the first wave. For wave conditions more severe than those causing the initial splashover, the booms were swamped by the waves as was expected. An examination of these test data showed that the relationship between the wave length and the wave period of the long-crested regular waves agreed well with the mathematical relationship obtained using Airy wave theory for both intermediate- and deep-water conditions."Deep water" is defined by ,.........................(1) where d = water depth, Ld = wave length for deep water. JPT P. 1007