Search

New York Harbor Pilots have expressed a concern to the New York District (NAN) about a mound that is approximately 1.5 miles seaward of the new limit of the Ambrose Channel. This mound is probably construction rubble that was placed there when the original Light Tower isolated and protected it somewhat from the main channel. The mound s diameter and depth are similar to the width and depth of the Ambrose Channel offshore reach. Now that the Light Tower is no longer marking this mound, the Pilots are concerned about whether a ship might experience larger or more dramatic ship motions due to possible amplification across the mound relative to similar transits in the offshore reach. The US Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), used the numerical models STWAVE and CMS-Wave to evaluate possible amplification effects of a range of wave conditions. The Channel Analysis and Design Evaluation Tool (CADET) was used to predict vertical ship motions due to wave-induced heave, pitch, and roll. Ship squat estimates calculated with the PIANC and Ankudinov empirical formulas were compared with the Beck, Newman, Tuck (BNT) squat predictions used in CADET. The net underkeel clearance based on these vertical ship motion components was used in a risk-based method of evaluating transits over the mound compared to similar transits in the main channel. These results were used to select a minimum dredge depth over the mound to insure that inadvertent transits over the mound would not incur any significant differences in ship response and potential grounding relative to similar transits in the offshore reach of the Ambrose Channel., The original document contains color images.

The mission of CHL is to understand better the effects of water levels, tides, waves, and currents on coastal structures such as beaches, inlets, harbors, jetties, and breakwaters and riverine structures such as spillways, levees, locks, and stilling basins. Combinations of analytical, numerical, and laboratory modeling tools are typically used to ensure optimal designs. Physical models are an important component of the CHL mission. They are engineering tools that are used to (a) improve understanding and gain insight into the physics of coastal and riverine processes, (b) test and optimize proposed designs, and (c) provide data sets for improving numerical models. Physical systems that are reproduced in the model follow similarity laws derived from dimensional analysis so that the model accurately represents the prototype. In general, the ratio of like quantities should be the same in both the model and prototype. Use of physical models is a well established engineering practice, especially in hydraulics and the design of ships (Hughes 1993; Chakrabarti 1994). William Froude (1810-1879) and Osbourne Reynolds (1842-1912) are among the most famous researchers relative to our branch of hydraulics. Froude studied the resistance of ships in a towing tank in 1870, which involved inertial and gravitational forces. Reynolds, a British engineer, developed the Reynolds number in his study of flow in parallel pipes to distinguish between laminar and turbulent flow conditions. The Froude and Reynolds numbers are two of the most important non-dimensional similarity parameters used in physical modeling. The CHL has been actively involved with physical modeling since its founding in 1929 to study the Mississippi River floods.

The Savannah District (SAS) is preparing a Final Engineering Appendix for the Savannah Harbor Expansion project. Initial vertical motion studies addressed extension of the entrance channel to deeper water along the existing alignment. After initial channel design, shallower offshore shoals were identified that could influence the safety and efficiency of navigation on the proposed channel alignment. The U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), conducted a vertical ship motion study to evaluate three proposed channel alignments: S-1, S-3, and S-8. These alignment changes (doglegs) are proposed to allow ships to reach deeper water in less distance, with reduced dredging costs. The Channel Analysis and Design Evaluation Tool (CADET) was used to predict vertical ship motions due to wave-induced heave, pitch, and roll. PIANC and Ankudinov ship squat were calculated and compared with the CADET squat predictions. The CADET days of accessibility, vertical ship motion allowances, and net underkeel clearance were calculated based on these vertical ship motion components to provide a risk-based method of evaluating different channel depths., The original document contains color images.

Squat is the reduction in underkeel clearance (UKC) between a vessel at-rest and underway due to the increased flow of water past the moving hull. The forward motion of the ship pushes water ahead of it that must return around the sides and under the keel. This water motion induces a relative velocity between the ship and the surrounding water that causes a water level depression in which the ship sinks. The velocity field produces a hydrodynamic pressure change along the ship similar to the Bernoulli effect. This phenomenon produces a downward vertical force (sinkage, positive downward) and a moment about the transverse axis (trim, positive bow up) that can result in different values of squat at the bow and stern . This combination of sinkage and change in trim is called ship squat. This Coastal and Hydraulics Engineering Technical Note (CHETN) summarizes the Ankudinov empirical formula for ship squat predictions used by the U.S. Army Engineer Research and Development Center (ERDC) Ship Tow Simulator (STS). This CHETN documents the Ankudinov squat formulas and describes two FORTRAN programs that were written for single and multiple ship speed applications. Two examples are given for a Panamax bulk carrier and Panamax tanker for both programs. A companion CHETN compares and validates the Ankudinov squat predictions with laboratory measurements of a Post-Panamax containership and field measurements of a Panamax containership, tanker, and bulk carrier in the Panama Canal. It also compares the Ankudinov formula with several of the Permanent International Association of Navigation Congresses (PIANC) empirical squat formulas. In Part II of this CHETN (ERDC/CHL CHETN-IX-20), further comparisons and validations with laboratory and field measurements are presented and discussed., This CHETN was prepared as part of the Deep Draft Navigation Research Program, Ship Simulations work unit. See also ADA508447, Part 2, ERDC/CHL CHETN-IX-20. The original document contains color images.

This Coastal and Hydraulics Engineering Technical Note (CHETN) is a continuation of the earlier CHETN entitled, Ankudinov ship squat predictions - Part I: Theory and FORTRAN programs, CHETN-IX-19 (Briggs 2009) that documented the Ankudinov squat formulas and described two FORTRAN programs for single and multiple ship speed applications. It also compared the Ankudinov formula with several of the PIANC empirical squat formulas for a Panamax bulk carrier and tanker. This CHETN continues the comparisons in Part I with actual laboratory and field measurements for validating the relative accuracy of the predictions. Comparisons are also made with several of the more popular PIANC (1997) empirical formulas., This CHETN was prepared as part of the Deep Draft Navigation Research Program, Ship Simulations work unit. See also ADA508447, Part 1, ERDC/CHL CHETN-IX-19. The original document contains color images.

A series of laboratory experiments were conducted for a range of model ships, irregular waves, wave-induced longshore currents, and jetty lengths to optimize the length of a proposed entrance channel jetty at Barbers Point Harbor, Hawaii. Eleven jetty configurations were studied on both sides of the entrance channel, with lengths varying from no-jetty to the proposed 450-ft length. Unidirectional spectral waves with wave periods of 6, 10, 14, and 18 sec, wave height of 7 ft, and incident wave directions of S25W (20 deg south of channel centerline) and S8oW (35 deg west of channel centerline) were generated. Wave-induced ship motions were obtained for 392 inbound and outbound transits with 1:75 scale models of the APL President Lincoln C9-Class containership, a modified Bunga Saga Empat bulk-cargo carrier, and a Kukahi oceangoing barge. The 375-ft-long jetty on the north side of the channel and the 2-ft depth transition inside the harbor were recommended. This conclusion was based on: (a) measured wave heights in the channel and barge basin, (b) ship and barge handling and maneuverability characteristics, (c) dye and current meter studies of the circulation patterns and flows in the channel, and (d) input from the sponsor, EPA, and harbor pilots., The original document contains color images.

The Norfolk District is preparing an Environmental Assessment for the use of sand sources off the coast of Cape Henry for future maintenance of the Virginia Beach, VA, shoreline. The primary purpose is to maintain a buffer for hurricane protection for structures landward of the existing beach. The Cape Henry Borrow Area is being considered as a sand source. The plan borrow scenario involves removing approximately 34.2 M cu yd of material from the borrow area over a period of 50 years. The study provided wave climate and potential longshore transport information and analysis for two bathymetric cases: existing bathymetry and planned excavation from the Cape Henry Borrow Area. These two cases bracket the range of expected conditions over the next 50 years and enable assessment of potential project impacts on littoral transport patterns along adjacent beaches during this time frame., The original document contains color images.

This Coastal and Hydraulics Engineering Technical Note (CHETN) documents the field data collection of ship motion data using Global Positioning System (GPS) sensors in Charleston, SC, Harbor during April 1999. Comparisons of measured squat with several empirical predictions are presented and discussed., The original document contains color images.

This Coastal and Hydraulics Engineering Technical Note (CHETN) presents an example of how to use the numerical model CGWAVE within the Surface Water Modeling System (SMS) Version 8.0 environment. Updates of SMS are frequent and may result in different control options. This CHETN was completed as part of the Tedious Creek, MD, work unit of the Monitoring Completed Navigation Projects program.The SMS is a comprehensive graphical user interface (GUI) for model conceptualization, mesh generation, statistical interpretation, and visual examination of surface-water model simulation results. The version described herein is SMS Version 8.1. It is the main model delivery system with pre- and post-processor capabilities for all the CHL numerical models including ADCIRC, TABS (RMA2, RMA4, SED2D), ADH, HiVEL, M2D, STWAVE, BOUSS2D, and CGWAVE. These integrated or interconnected models provide circulation and/or wave climate from a range of coastal processes including waves and currents, sediment transport and morphology change, channel infilling and inlet morphology, and dredged material fate. SMS provides the tools and macros for editing and display for mesh development, coordinate conversion, model connectivity, animations, and comparisons., The original document contains color images.

This report describes analytical and numerical modeling efforts to quantify the performance and response of a new type of Rapidly Installed Breakwater System (RIBS) being developed at the U.S. Army Engineer Research and Development Center's (ERDC) Coastal and Hydraulics Center (CHL). The RIBS is a floating breakwater with two legs in a 'V', shape in plain view which provide a sheltered region from waves and currents. The RIBS concept was initially developed to address problems encountered by military personnel during Logistics-Over-The-Shore (LOTS) operations. The primary problem occurs during these operations when sea states become elevated and negatively impact crews trying to discharge cargo and equipment onto smaller vessels from Tactical Auxiliary Crane Ships (TACS) and roll-on/roll-off (RO/RO) vessels. The performance of a floating breakwater can be quantified by the wave transmission coefficient. The structural response can be estimated using the wave-induced dynamic pressures along the structure. These pressures can be used to calculate the wave forces and moments. Preliminary results from the RIBS field study at Cape Canaveral, FL, May 1999, are presented and compared to analytical and numerical models of the RIBS wave transmission coefficient and dynamic wave pressures.

This dissertation describes an integrated study of analytical, numerical, laboratory, and field modeling efforts to quantify the performance and response of a new type of rapidly installed breakwater system (RIBS) being developed at the U.S. Army Engineer Research and Development Center's (ERDC) Coastal and Hydraulics Laboratory (CHL), located in Vicksburg, MS. RIB is a floating breakwater with two legs in a 'V' shape in plan view which provide a sheltered region from waves and currents. The performance of a floating breakwater can be quantified by the wave transmission coefficient. The structural response can be estimated using the wave-induced dynamic pressures along the structure. These pressures can be used to calculate the wave forces and moments. Both the measured wave transmission coefficient and dynamic pressure were compared to analytical and numerical predictions and several new empirical parameters have been developed.

The U.S. Army Engineer Research and Development Center (ERDC) performed the Rapidly Installed Breakwater System (RIBS) XM2000 Experiment in June-July 2000 at the Naval Air Station (NAS), Pensacola, Florida. An extensive instrumentation was installed on the RIBS in order to measure wind, waves, RIBS motion, and mooring line loads. During the experiment, a first-level data analysis and data quality checking for collected data was executed in order to allow a reliable second-level analysis and additional post-processing.

Laboratory measurements of wave shoaling and breaking on an ebb current were made in an idealized inlet in a wave basin. The experiment arrangement, procedures, and data analysis are described. The wave and ebb current measurements showed increased shoaling and breaking (compared to no current, shifting of the spectral peak to lower frequencies, and energy dissipation concentrated at the spectral peak and higher frequencies). The measurements were used to evaluate and develop formulations of wave dissipation on a current for application to a spectral wave model. Whitecapping dissipation formulations underpredicted breaking on a current in shallow water, whereas the bore-based wave dissipation relationship of Banjes and Janssen and a relationship developed in this study provided good estimates of wave-height decay on an ebb current Tables of the wave and current parameters are provided as an appendix.

A 1:60 scale (undistorted) three-dimensional hydraulic model was used to investigate the design of proposed breakwater modifications at Newport North Marina, Yaquina Bay, OR, with respect to wave and current conditions in the harbor and sediment patterns at the site. The model reproduced the existing marina and a portion of the Yaquina River from west of the U.S. Highway 101 bridge upstream. Proposed improvements consisted of breakwater modifications at the marina entrance. A 12.2-m-long (40-ft-long) unidirectional, spectral wave generator, a water circulation system, an automated data acquisition and control system, and a crushed coal tracer material were used in model operation. Test results led to the following conclusions: (a) Existing conditions are characterized by rough and turbulent wave conditions during periods of storm wave attack. Wave heights in excess of 0.9 m (3 ft) occurred in the marina mooring areas. (b) Preliminary tests for the three originally proposed design alternatives (Plans 1-3) indicated that none of the test plans would meet the original 0.3-m (1-ft) criterion in the marina mooring area. (MM)

The state of Hawaii identified the need for Barbers Point Harbor to accommodate larger ships and increase the number of available berths. Modifications to the harbor were proposed, including widening the entrance channel, and deepening (from 38 to 45 ft) and expanding the harbor basin (1,000-ft by 1,100-ft area on the northeast side of the harbor). Physical and numerical (computer) model studies were conducted from September 1990 to June 1992 at the U.S. Army Engineer Waterways Experiment Station to evaluate the technical feasibility and optimize the design of the proposed modifications. In addition to physical and computer model studies, navigation studies were also conducted using a scale model C9 container ship in the physical model. Recommended modifications to Barbers Point Harbor include flaring of the outer 1,000 ft of the entrance channel from 450 ft wide to 750 ft wide, deepening the channel to 49 ft, constructing a 450-ft jetty along the north side of the entrance channel, deepening the harbor to 45 ft, and dredging a 1,100-ft by 1 ,100-ft expansion area in the harbor basin.

This report describes an experimental study of the interaction of monochromatic waves and an ebb current in and near a shallow entrance channel. Laboratory experiments were performed in a three-dimensional basin with a 1 vertical (IV) on 30 horizontal (30H) fixed-bed slope. Two entrance channel configurations were tested: one with a IV on IH side slope and the other with vertical sides. Both had equal cross-sectional areas and were 1-m wide, 10-cm deep, and 5.5-m long. Four small amplitude waves were generated using the directional spectral wave generator (DSWG). These waves had wave periods of 0.75 and 1.50 sec, directions of 0 deg and 20 deg (relative to normal to the DSWG), and wave heights of 5.0 cm. Steady ebb currents of 10, 20, and 30 cm/sec were generated using a 0.16-M3 pump. Measurements were made with capacitance wave gages and triaxial ultrasonic current meters in a 5-m by 6-m area. The six cross-shore transects had seven gages with a 1-m spacing between gages.... Ebb current, Wave-current interaction, Three-dimensional physical models., Prepared in collaboration with Cornell Univ., Ithaca, NY 14853. Dept of Civil and Environmental Engineering.

A three dimensional, physical model study of the effects of wave directionality on wave transformation in the nearshore region was recently completed in the directional spectral wave basin. The model consisted of a 1:30 slope beach with plane-parallel contours, similar to the Torrey Pines Beach in southern California. Irregular waves, typical of unimodal and bimodal unidirectional and directional spectra, were created and tested. An array of 20 capacitance wave gages was used to measure surface wave elevations. This array consisted of offshore and nearshore, high-resolution linear arrays to quantify directional distributions and a cross-shore gage array along the center line to study wave transformation. Results are compared with two dimensional flume test data of similar unidirectional waves and will be used to improve several existing numerical models. The goal of this research is to provide more realistic estimates of nearshore conditions by incorporating the effects of directional distributions in numerical models., See also Volume 2, ADA241434.

Physical Description: 9 VHS videos; black and white; silent; 180 minutes; 3/4 in. Short film clips of 54 wave conditions which shows direction of wave directionality on wave transformation in the near shore region., Includes documentation, AD-A242 087. See also Volume 2, AD-A241 434.