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| Title: | DAMPING OF GRAVITY WAVES BY FIELDS OF FLEXIBLE VEGETATION | |
| DOI No: | 10.1142/9789812709554_0043 | |
| Source: | COASTAL ENGINEERING 2006 (pp 491-503) | |
| Author(s): | Sávio Freire Lima
Ocean Engineering Program/COPPE, Federal University of Rio de Janeiro, Caixa Postal 68508, 21949-900, Rio de Janeiro, RJ, Brazil Claudio Freitas Neves Ocean Engineering Program/COPPE, Federal University of Rio de Janeiro, Caixa Postal 68508, 21949-900, Rio de Janeiro, RJ, Brazil Nara Maria Luzzi Rosauro Hydraulic Research Institute, Federal University of Rio Grande do Sul, Av. Bento Gonçalves, 9500, 90.650-001, Porto Alegre, RS, Brazil |
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| Abstract: | This work presents a method for determining wave damping through vegetation fields which does not assume the individual plants as rigid, fixed structures. The proposed model combines empirical observations and a mathematical formulation that computes the depth integrated, time averaged force on the stem, based on a single unknown parameter, the drag coefficient. Video images of the movement of one isolated stem were used to calibrate the model. Experiments were conducted on a wave flume, using stretches of 6 mm flexible nylon ropes to simulate a particular type of vegetation, Brachiaria subquadrípara. The expression of the force on a single stem is introduced on the time averaged, depth integrated momentum equations for the fluid as a resistance term, multiplied by the spatial density of stems and by an ensemble coefficient. The wave height decay can thus be determined. Experimental results indicate that the interaction among stems plays an important role on total wave decay. | |
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