Final Report [Apra Harbor, Guam]

Contract NOy-12561 was initiated 28 June 1945 for the purpose of conducting hydraulic model experiments to guide the extensive harbor improvements then in process and planned for, at Apra Harbor, Guam, M. I. The contract was continued through change orders and finally terminated on 30 November 1954. The Apra Harbor investigation was completed at the end of 1948, and during the following contract period activity was directed along the lines of basic investigations of wave phenomena as they affect harbors and harbor structures. The program of the Laboratory was formulated and directed by Robert T. Knapp, Professor of Hydraulics, during the Apra Harbor studies and those immediately following. During this time laboratory facilities were designed and procured and the general program, which was followed by the project until its completion, was delineated. Dr. Warren O. Wagner was supervisor of the project during most of the Apra Harbor study. From the spring of 1949 until the termination of the contract, the project was supervised by Mr. John H. Carr. In the following sections of this report, the aim and procedure of the several investigations are outlined, and the principal results summarized

Model Studies of Mobile Breakwaters Progress Report for July-November, 1949

This report covers further work on the refraction of waves by opposing currents, and is essentially an elaboration of earlier results. Two types of currents have been considered, a horizontal flow of substantially constant velocity from surface to bottom, and a horizontally stratified flow characterized by high velocities near the surface and relatively low velocities in the opposite direction across the rest of the vertical section. For the first type of current, a revised theoretical treatment is presented, together with experimental results which are in good agreement with the theory. For the second type of current, experimental results have been obtained for a range of current intensities much higher than would be practical in a prototype installation. The results of these experiments do not change the earlier conclusion that the refraction of waves by opposing currents, and hence the pneumatic breakwater, is not a practical means for materially reducing wave disturbances. These experiments do extend the experimental investigation to cover the complete range of wave types, from deep-water to shallow-water and of current values to well over any conceivable prototype range

Harbor Development Study Progress Report for June - December, 1949: Model Studies for Harbor Development

The general objective of the Harbor Development Study is the investigation of the wave energy distribution in simple harbor areas, with the specific objective of determining design principles which will permit the prediction of harbor performance. The progress accomplished to date has consisted of the analysis of the problem in terms of applicable physical principles, the review of present knowledge or these principles, the formulation of a general laboratory program, and the construction of the laboratory facilities required for the first phase of the program. This report considers each of these items in turn

Observation of Infrared and Radio Lines of Molecules toward GL2591 and Comparison to Physical and Chemical Models

We have observed rovibrational transitions of acetylene and HCN near 13 microns in absorption toward GL2591. We also observed rotational lines of CS, HCN, H2CO, and HCO+. The combined data are analyzed in terms of models with a cloud envelope with density gradients and discrete regions of hot, dense gas, probably near the infrared source. The abundance of HCN is enhanced by a factor of 400 in the gas producing the infrared absorption, in agreement with chemical models which involve depletion of molecules onto grains and subsequent sublimation when temperatures are raised.Comment: 34 pages, postscript with 14 postscript figure files, uuencoded compressed and tar'ed; unpacks self with csh. In case of problems, contact [email protected]

Harbor Surging

[no abstract

Interim Report December 1952-March 1953

Change Order "O" to Contract NOy-12561, under which the Laboratory is now operating, provides as a general objective the investigation of the forces and pressures exerted by waves on fixed plane barriers inclined at any angle to the sea surface, and on stepped or off-set plane barriers. In keeping with this objective, the Laboratory is endeavoring to develop a program which will combine a basic investigation of the mechanics of wave-induced forces with the production of immediately useful data. It is expected, for instance, that the results of experimental farce and pressure measurements on plane barriers, aside from their scientific value, can be used with profit in calculating the stability of gravity-type or caisson breakwaters against sliding and overturning. Since this program represents a new field of work for this Laboratory, the initial portion of the contract period has been devoted to the alteration of existing laboratory equipment, and the design and construction of required new equipment. In all of the~ modification and development of force and pressure measuring equipment, an effort has been made to design for maximum flexibility. Thus, the resulting basic units can be easily adapted to the various specific phases of the current or future investigations, such as breaking and non-breaking wave conditions, and many configurations of structures for which force or pressure data will be of interest. At this time, all equipment for the pressure measuring and orbit investigation programs has been completed, and work on these programs has begun. The force measuring apparatus is under construction, with completion estimated as June 1, 1953. In view of the considerable investment in time and funds made to equip the Laboratory for this new type of investigation, this report has been prepared to describe in some detail the alteration of existing equipment and the development of new equipment

Mobile Breakwater Studies

This report presents the results of studies of the problems and possibilities of mobile breakwaters. The field of study was divided into two main parts: the general investigation of the hydromechanical laws pertaining to the problem of wave height attenuation, and the laboratory investigation of some specific devices which offered some promise of meeting minimum operational requirements

Breaking Waves Forces on Plane Barriers

For the past twenty-four months this Laboratory has been engaged in a study of wave action on barriers. The first half of this investigation was limited to cases of wave reflection from various structures. The experimental program for this first phase of the investigation included both the development of instrumentation and experimental techniques and the measurement of wave forces and pressures acting on plane barriers inclined at various angles and on a family of curved and stepped-face barriers selected by the Bureau of Yards and Docks. The results of that program (Refs. 1 and 2) include: (1) The development and experimental verification of relatively simple analytical expressions for the force and pressure distributions exerted on vertical plane barriers by reflecting waves. These expressions include a second-order double wave frequency term which becomes of increasing importance for small values of L/d (wavelength to water depth ratio), and which has not heretofore been considered in connection with wave forces on barriers. (2) The demonstration of a simple relationship between the forces acting on a vertical plane barrier and those acting on plane barriers inclined at angles up to 30° from the vertical, and on certain curved and stepped-face barrier profiles. The extension of the program to include the study of breaking waves was a logical consequence of the earlier work, both because of the engineering importance of the breaking wave problem and because the apparatus and experience developed in the first phase promised to be directly applicable to such a study. Previous knowledge of the breaking wave problem was limited almost solely to analysis and measurements of the impulsive or shock pressures developed by breaking waves. Since these short-duration, high-intensity pressures appear in some respects to be unrealistic as the basis for design, this investigation approached the problem by determining the force-time history during the entire wave cycle to permit the evaluation of other aspects of the force function than the singular one of initial impulse. The study was necessarily restricted to a few values of geometric and wave parameters, but the results, as expressed in dimensionless parameters, promise to provide useful data for a wide range of design problems. These results include: (1) Determination of wave steepness and water depth parameters which result in wave breaking for various plane barrier and foreshore geometries. {2) The correlation of measured breaking wave impulse with computed wave momentum derived from solitary wave theory. {3) Experimental determinations of the relationship between wave parameters and the magnitude and location of a maximum effective force believed valid for design purposes, expressed in terms of the computed wave momentum