CGWAVE Interface

CGWAVE (Panchang & Xu 1995) is a 2D finite element model based on the elliptic mild-slope wave equation. It is similar to wave models HARBD (Chen and Mei 1974) and PHAROS (Kostense et al. 1986). CGWAVE can simultaneously simulate the effects of refraction, diffraction, reflections by bathymetry and structures, dissipation due to friction and breaking, and nonlinear amplitude dispersion. The computational capabilities of CGWAVE model permit the modeling of large coastal regions. The governing equations of CGWAVE pass, in the limit, to the deep and shallow water equations, making this model applicable to a wide range of frequencies, including short wind waves, swell, and infra-gravity waves.

A mesh for use with CGWAVE must match one of three domain shapes including rectangular, semi-circular, and circular. SMS includes tools in the Map Module to create a network with a valid domain shape (see the tutorial for CGWAVE). Therefore, it is strongly recommended that the Map Module be the principal method for creation of new networks. The Mesh Module may be used to create a mesh, however in the case of CGWAVE the Mesh Module primarily is useful for network editing and assigning model parameters required by CGWAVE. These model parameter commands are grouped in the CGWAVE menu.

Solutions generated by CGWAVE can be visualized in SMS in two ways. The most straightforward method is to read the solution file. When SMS reads this solution file, it translates the data and creates data sets for wave amplitude, direction and phase. If additional functions are desired from the wave characteristics, they must be generated using a CGWAVE translating utility. An example of this is included in the CGWAVE reference manual. The translating utility creates generic data set files that can be imported using the Data Browser. The CGWAVE interface includes the following components:

• Model Control

• Boundary Conditions

• Display Options

• CGWAVE Tools

• CGWAVE Menu

• Model Check

• CGWAVE Simulation

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• Run CGWAVE

Functions

CGWave computes properties that illustrate the characteristics of waves in a coastal area. To adequately perform this approximation, the mesh must contain several elements per wavelength. To ensure this is the case, the user can use the facility for creating functions to compute the wavelength for all data points in the model domain. This function can be scaled using the data calculator to create a size function which guides the automatic mesh creation process from a conceptual model in the Map Module.

Display Options

Nodes and nodestrings that have been assigned boundary conditions can be shown with their own display attributes. The display of these entities is accessed through the Mesh Display Options dialog. To open this dialog select the Display Options command in the Display menu or click on the Display Options macro while in the Mesh Module.

Inside the Mesh Display Options dialog, click the Options button next to the Nodestrings toggle to open the CGWAVE Nodestring Display Options dialog.

To change the display options for a specific boundary condition type, click the color box next to the option. For nodestring boundary conditions, the color shows whether the nodestring is assigned as ocean, coastline or floating barrier.