Exterior Reflections in Elliptic Harbor Wave Models
Publication: Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 122, Issue 3
Abstract
Traditional elliptic harbor wave models are based on the assumptions that the exterior sea region (i.e. the region outside the computational grid) is of constant depth and that the exterior coastlines are collinear and fully reflecting. This paper demonstrates that for most coastal regions, where these assumptions are generally not true, their effect on model results is substantial. This leads to unreliable simulations. Enlarging the model domain to overcome their effects is cumbersome and often prohibitive. To overcome these difficulties, the use of parabolic approximations of the mild-slope wave equation as open boundary conditions is explored. Suitable parabolic equations are derived and interfaced with an elliptic finite-element model. Since the parabolic approximation does not describe wave scattering as rigorously as the traditional method, the new model is tested against analytical and other solutions for cases where scattering is extensive. Errors resulting from the parabolic approximation are found to be extremely small. Further model tests show that for the generally realistic case where exterior reflection coefficients are less than unity, the new method requires considerably smaller domains than the traditional method, resulting in reduced modeling effort. The model is also applied to Toothacher Bay, Maine, and the use of the parabolic boundary conditions eliminates many spurious features in the simulation.
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Published In
Journal of Waterway, Port, Coastal, and Ocean Engineering
Volume 122 • Issue 3 • May 1996
Pages: 118 - 126
Copyright
Copyright © 1996 American Society of Civil Engineers.
History
Published online: May 1, 1996
Published in print: May 1996
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