Publications

Mathieu instability for a spar platform arises when there is a harmonic variation in the pitch restoring coefficients caused by large heave motion and the period of the heave motion is half of the pitch natural period. The pitch restoring coefficient can be represented by a function of the displaced volume and the metacentric height of spar hull. [Read more…] about Mathieu Instability of a Spar Platform with Mooring and Risers

Nonlinear multi-contact coupling between vertical risers and guide frames inside the spar moon-pool is studied. The existing numerical model for hull/mooring/riser coupled dynamics analysis treats riser as an elastic rod truncated at the keel (truncated riser model), and the risers are free to slide in vertical direction with constant tension, while restricted in horizontal direction. [Read more…] about The Effect of Nonlinear Multi-Contact Coupling with Gap Between Risers and Guide Frames on Global Spar Motion Analysis

When dredged materials proposed for open-water placement are found to require isolation form the benthic environment due to the presence of contaminants, capping may be appropriate for consideration as a management action. This report is intended to provide technical guidance for evaluation of capping projects. [Read more…] about Guidance for Subaqueous Dredged Material Capping

Hypoxia, and occasionally anoxia, occur annually in the northern Gulf of Mexico. Important physical properties preceding and partially causing hypoxia and the spatial extent of hypoxia are determined. [Read more…] about Nearshore Hypoxia in the Bottom Water of the Northwestern Gulf of Mexico from 1981 to 1984

Surface water wave elevations and kinematics from four unidirectional irregular wave trains, with a Pierson and Moskowitz or JONSWAP random wave spectrum, were measured in the laboratory using resistance wave probes and a laser Doppler anemometer. [Read more…] about Comparison of Experimental Irregular Water Wave Elevation and Kinematic Data with New Hybrid Wave Model Predictions

Numerical predictions of irregular wave elevations and velocities based on the hybrid wave model are compared with two sets of laboratory measurements and are also compared with the related predictions by linear random wave theory and its ‘stretching’ and ‘extrapolation’ modifications. [Read more…] about Hybrid Wave Model for Unidirectional Irregular Waves — Part 2. Comparison with Laboratory Measurements

A new hybrid wave model for the prediction of the kinematics and wave evolution of unidirectional irregular wave trains is presented. The model considers the effects of the interaction between the wave components of an irregular wave train up to the second order of wave steepness. [Read more…] about Hybrid Wave Model for Unidirectional Irregular Waves — Part 1. Theory and Numerical Scheme

This report was authorized as a part of the Civil Works Research and Development Program by Headquarters, US Army Corps of Engineers (HQUSACE). The work was conducted under Work Unit 32748,” Detached Breakwaters for Shoreline Stabilization,” under the Coastal Structure Evaluation and Design Program at the Coastal Engineering Research Center (CERC), US Army Engineer Waterways Experiment Station (WES). Messrs. JH Lockhart and JG Housley were HQUSACE Technical Monitors.

The kinematics of an irregular wave is characteristically different from that of a regular wave with similar wave height and frequency in two respects. First, an irregular wave induces larger particle velocities near the surface and smaller velocities at greater depths than that for a regular wave. [Read more…] about Component Wave Interactions and Irregular Wave Kinematics

Results of recent research on experimental investigation of wave‐fluid particle kinematics just prior to breaking using laser Doppler anemometry are presented. Extreme transient waves, similar to those found in hurricane Camille, and an “equivalent” regular wave, often used for design purposes, are generated and their kinematics measured. [Read more…] about Kinematics of 2-D Transient Water Waves Using Laser Doppler Anemometry