EE - Artigos Publicados em Periódicos
URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/513
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- ItemWave propagation in jettied entrance channels. II: observations(1991) Melo Filho, Eloi; Guza, RobertField measurements of surface gravity waves along the center line of the straight, 1 km long, 8 m deep, 250 m wide Mission Bay entrance channel (bounded by rubble-mound jetties) are compared to a model developed in a companion paper by Melo and Guza. The observations show a rapid downchannel decay of wave energy. Additionally, the observed ratio of significant wave heights between any two stations along the channel axis is rather constant despite the different wave and current conditions encountered. The model, with all empirical coefficients determined with existing parameterizations, agrees qualitatively well with these observations. These model results are insensitive to the details of the motions and dissipation occurring within the jetties so long as an appropriate amount of energy is lost at these lateral boundaries. The wave height on the center line of a wide channel with highly absorptive jetties is controlled by diffraction. In fact, the observations and model results on the center line at Mission Bay are similar to previously published simplified models with the jetties replaced by strips of appropriate bottom dissipation and also to the decay along the center line of a breakwater gap with the gap width equal to the entrance channel width.
- ItemWave propagation in jettied entrance channels. I: models(1991) Melo Filho, Eloi; Guza, RobertA model for the propagation of sea and swell waves in a channel bounded by rubble-mound jetties is presented. The model combines elements of earlier work on waves normally incident on a breakwater with a modified diffraction model based on the linear mild-slope equation. For grazing-angle (relative to the jetty axis) wave incidence, a parabolic approximation to the governing equation is used to obtain numerical solutions for monochromatic long waves propagating down the channel. An initially plane wave evolves into a spatially complex pattern as dissipation occurs along the jetties and energy is drawn from the channel interior by diffraction. Comparisons of the model to field observations are presented in a companion paper.
- ItemConsiderações sobre a hidráulica de canais fluviais e de canais de maré(1998) Melo Filho, EloiEste trabalho apresenta uma contribui- ção no sentido de inserir o tópico canais de maré no escopo da hidráulica de canais tradicional. As peculiaridades próprias dos escoamentos em canais fluviais e em canais de maré são discutidas e comparadas tanto do ponto de vista físico quanto do matemático. Alguns tópicos específicos são tratados em detalhe: as equações de Saint-Venant são comparadas às equações de Águas Rasas; uma abordagem alternativa à tradicional para escoamentos permanentes em canais fluviais é apresentada; a possibilidade de ocorrência de escoamentos super-críticos em canais de maré é analisada e algumas propriedades peculiares às ondas de cheias e às ondas de maré são revisadas e discutidas.
- ItemOn the measurement of directional wave spectra at the southern Brazilian coast(1999) Alves, Jose Henrique Gomes de Mattos; Melo Filho, EloiThe detailed reconstruction of the directional spectrum of wind waves from measurements of the wave field is an essential requirement for several applications, including the numerical modeling of wave evolution. Three reconstruction techniques that provide estimates of the directional distribution function D f ;u ; given the one-dimensional frequency spectrum, are compared using data from a coastal locality at the southern Brazilian coast. The techniques are the maximum entropy method (MEM), the Fourier Expansion Method using a cos2 type function (FEMcos) and the Fourier Expansion Method using a sech type function (FEMsech). The main patterns of the wave climate at the study site are qualitatively assessed. Three main sea states, including swell, transition between local sea and swell, and directionally bimodal wind sea, are identified. Time series from three events associated with the main sea states provide test cases for inter comparison of the three reconstruction techniques. Maximum entropy estimates of D f ;u provide results that are more consistent than those obtained from the two FEM techniques in all cases considered. q1999 Elsevier Science Ltd. All rights reserved.