Harbor Development Study Theoretical Studies

Abstract

Investigation of the theoretical aspects of water-wave diffraction through an opening in a breakwater has progressed in two principal directions. First, the work of Penney and Price (1), in adapting Sommerfeld's solution of the optical diffraction problem to the case of water-wave diffraction, has been studied with a view toward generalizing it to suit any angle of wave incidence. In the second place, pursuing the method of a group at the Massachusetts Institute of Technology (2,3,4,5), an application of Mathieu functions to the case of water-wave diffraction has been made, to achieve an exact solution of the problem. This second phase of the investigation seems to be especially fruitful in that the total amount of energy entering a harbor, and the distribution of energy within the harbor, can be numerically computed. Tables of constants involved in this computation are being published by the National Bureau of Standards, and will be generally available soon. computation forms have been devised which permit routine calculation of the desired quantities by sub-professional personnel. Although the work of calculation has been reduced to a straightforward task, the amount of work which will be required for a complete set of energy distribution plots, covering a wide range of gap widths and wave directions, is so great that efforts are being made to have this computing performed by IBM machine at the National Bureau of Standards' Institute for Numerical Analysis.