Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed BuoysÃÂÃÂÃÂÃÂ that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate high-resolution (fine scale, very near-field) fluid/structure interaction simulations of buoy motions, as well as array-scale, phase-resolving wave scattering simulations. These modeling efforts will utilize state-of-the-art research quality models, which have not yet been brought to bear on this complex problem of large array wave/structure interaction problem

The impact of wave energy converter arrays on wave-induced forcing in the surf zone

An alternative metric for assessing nearshore hydrodynamic impact due to Wave Energy Converter (WEC) arrays is presented that is based on the modeled changes in alongshore radiation stress gradients in the lee of the array. The metric is developed using a previously observed relationship between measured radiation stresses and alongshore current magnitudes. Next, a parametric study is conducted using the spectral model SWAN to analyze the nearshore impact of different WEC array designs. A realistic range of array configurations, locations, and incident wave conditions are examined and conditions that generate alongshore radiation stress gradients exceeding a chosen impact threshold on a uniform beach are identified. Finally, the methodology is applied to two permitted WEC test sites to assess the applicability of the results to sites with more realistic bathymetries. For these sites, the overall trends seen in the changes in wave height, direction, and radiation stress gradients in the lee of the array are similar to those seen in the parametric study. However, interactions between the wave field and real bathymetry induce additional alongshore variability in wave-induced forcing. Results indicate that array induced changes can exceed the natural variability up to 15% of the time with certain array designs and locations

Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array of newly developed BuoysÃÂÃÂÃÂÃÂ that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate high-resolution (fine scale, very near-field) fluid/structure interaction simulations of buoy motions, as well as array-scale, phase-resolving wave scattering simulations. These modeling efforts will utilize state-of-the-art research quality models, which have not yet been brought to bear on this complex problem of large array wave/structure interaction problem

SEICHING IN A LARGE WAVE FLUME

Time series of cross-shore velocity and water surface elevation obtained during the CROSSTEX laboratory experiment show the presence of low frequency motions that are characteristic of the well-known phenomenon of wave basin seiching. In general, the modes appear to be mostly standing in nature and the individual modes do not appear to be directly forced by the paddle motions. A preliminary wavelet analysis shows they have well-defined frequencies that are well-predicted by a linear analysis that treats the motions as unforced standing waves. There are, however, some additional observed features that appear to be unique to this case. For example, wavelet analysis also indicates a complex time dependence of the modal amplitudes, which suggests the modes are interacting nonlinearly. In addition, observations of the spatial mode structures hint at direct evidence of dissipation (such as wave breaking) occurring in the higher modes. Finally, our initial nonlinear analysis approximately reproduces the time scales for modal energy exchange observed in the experiments

Data for Runups of unusual size: rogueness and variability of swash

This repository item contains the files needed to reproduce the results reported in the published work entitled "Runups of unusual size: rogueness and variability of swash" in the Journal of Geophysical Research. As described in the publication, the results described within it pertain to simulations of wave runup for various configurations of beaches using various idealized surface gravity wave conditions. All discussed results pertain to a model-generated data set using the publically-available code "funwavec" for wave propagation and runup calculations (see http://falk.ucsd.edu/funwaveC.html to download the code). The files provided herein are input files or post-processing code that can be used to re-create the entire model data set that was utilized in the publication. More specifically, the provided files are: 1. funwaveC_master: control file to run the simulations including the seeds to the random number generator 2. funwaveC_pre: to generate bathymetry and input files for funwaveC 3. funwaveC_runup_postProcessing: post-processing code to determine runup values 4. wavemakerInput.csv: Combinations that were simulated in this pape