complete mild-slope equation (except for very small domains). Typically, coastal wave
propagation problems involve the modeling of very large domains. For example, consider
the case of 12 second waves in water of 15 m depth. The wavelength L is about 136 m;
an 8 km by 8 km domain is about 3600L2 in size. The difficulties associated with solving
such large problems spawned the development of several simplified models (e.g. the
"parabolic approximation" models (Dalrymple et al. 1984; Kirby, 1986), RCPWAVE
model (Ebersole, 1985), EVP model (Panchang et al 1988), etc.).
However, these
simplified models compromised the physics of the mild-slope equation: they model only
one- or two-way propagation with weak lateral scattering.
Such models are hence
applicable only to rectangular water domains for a very limited range of wave directions
and frequencies. Most realistic coastal domains with arbitrary wave scattering cannot be
modeled with these simplified models.
This manual describes a wave model called CGWAVE developed at the University
of Maine under a contract for the U.S. Army Corps of Engineers, Waterways Experiment
Station. CGWAVE is a general purpose, state-of-the-art wave prediction model. It is
applicable to estimation of wave fields in harbors, open coastal regions, coastal inlets,
around islands, and around fixed or floating structures. While CGWAVE simulates the
combined effects of wave refraction-diffraction included in the basic mild-slope equation,
it also includes the effects of wave dissipation by friction, breaking, nonlinear amplitude
dispersion, and harbor entrance losses. CGWAVE is a finite-element model that is
interfaced to the SMS model (Jones & Richards, 1992) for graphics and efficient
implementation (pre-processing and post-processing). The classical super-element method
as well as a new parabolic approximation method developed recently (Xu, Panchang and
Demirbilek 1996), are used to treat the open boundary condition. An iterative procedure
(conjugate gradient method) introduced by Panchang et al (1991) and modifications
suggested by Li (1994) are used to solve the discretized equations, thus enabling the
modeler to deal with large domain problems. This manual provides a brief review of the
basic theory in Sections 2 and 3, an overview of how this theory is implemented in
4
Previous Page
