Study of Water Waves with a Submerged Flat Plate Usingotential-Vorticity Decomposition
Date Issued
2008
Date
2008
Author(s)
Wen, Chia-Chi
Abstract
Abstracteywords：Submerged flat plate, Potential-Vorticity decomposition, Boundary integral method, Vortex method, Reflection coefficients, Higher harmonics. n this research, a numerical scheme that employs a potential-vorticity decomposition is used to investigate the interaction of periodic water waves with a submerged flat plate. This method uses Helmholtz decomposition to decompose the flow field into its rotational and irrotational parts. The vortical flow field is solved via a vortex method; the irrotational flow field and the motion of the free surface are solved using a boundary integral technique. The major advantage of this method is the efficiency of the boundary integral method for solving the free surface motion, and the essentially grid-free nature of the vortex method for the vorticity field, which is predominantly confined in compact regions. series of simulations were conducted to study the free surface deformation and the flow pattern. Although the vortical regions are mainly confined near the two sharp edges of the plate, their scales are relatively larger then the thickness of the thin plate. In order to compare the results obtained from a potential-flow approach and the viscous-flow model, at first we present the numerical results in which the vortical part is neglected, and then the generation and evolution of vortices as well as their effects are reported.ccording to the numerical results, the position of the thin flat plate affects the deformation of the free surface significantly. Furthermore, vortex effects are not negligible for the flow near the flat plate, and may affect the reflection of surface waves and the generation of higher harmonics. Even if linear waves cases, vortices around the tips of the thin plate affected the effective boundary. This may lead significant error in the analysis using a potential flow theory.
Subjects
Submerged flat plate
Potential-Vorticity decomposition
Boundary integral method
Vortex method
Reflection coefficients
Higher harmonics
Type
thesis
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