| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 97 === The scattering of large-scale ocean structure wave forces by an array of vertical circular cylinders. Au and Brebbia (1983) used the boundary element method (BEM) to calculate wave height and wave force. However, these studies are required as the basis for constant water depth. In practical engineering applications were restricted. Berkhoff (1972) used the linear wave theory to derive for mild-slope equation (MSE), However, MSE was non-homogeneous Helmholtz equation. If calculated by BEM, it will have to complex points of the field. So, Zhu (1993a) application of dual reciprocity boundary element method (DRBEM) calculated for wave diffraction and refraction problem. But MSE derived process ignored bottom curvature term and bottom slope squared term. Bed may not be able to respond to impact of the wave disturbance. Thus, Chamberlain and Porter (1995) derived for modified mild-slope equation (MMSE), which includes the bottom curvature term and bottom slope squared term. The studies showed that the MMSE was more accurate than the MSE calculated on the relative wave field in the wave height.
Therefore, this paper application of DRBEM to calculated large-scale structures surrounding the wave force from MSE and MMSE equation.Study results of this paper, the calculated results were compared with those by Liu and Lin (2007), MacCamy and Fuchs (1954) and Linton and Evans (1990) are conducted, in order to show the applicability of this model. Good agreements were obtained. So the numerical calculations apply to regular waves pass through cylinders making wave force in constant depth、varying depth; Effect with the bottom curvature term and bottom slope squared term, MSE and MMSE wave field have more obvious changes in intermediate water depth. And the dimensionless wave force due to the terrain slope, incident wave direction and position of pile groups. When the incident wave direction and configuration of pile groups in the same direction, Wave force changes range ( value) also became smaller; the bed slope which more steep, MSE and MMSE dimensionless wave force had the greater difference.
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