Application of Reproducing Kernel Particle Method for Coupled Fluid-Structure Interaction Analysis

• Main Authors: Sun, Chien-Ting, 孫健庭
• Other Authors: Guan, Pai-Chen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/27q7jk

博士 === 國立臺灣海洋大學 === 系統工程暨造船學系 === 106 === With the advancement of computer technology in computational efficiency, the Fluid-Structure Interaction (FSI) simulations become more and more applicable in state of the practice point of view. Also, as the demand of advanced engineering applications increases in Taiwan, the FSI analysis has become the major topic in the field of naval architecture, ocean engineering and warship construction, etc. Also, there are very few commercial CAE software available for state of practice FSI applications. Therefore, the purpose of this study is to propose and to develop a numerical method that uses the Lagrangian framework for the coupling of fluids and solids analyses. The general numerical methods, when dealing with FSI problems, usually use mixed Lagrangian and Eulerian mesh to describe solid and fluid behavior respectively. When the solid moves or deforms, we need to remesh the region close to the solid-fluid interface. This step usually loses the equilibrium due to the interpolation of state and field variables on the new mesh grids. Also, for the open flow boundary, Euler mesh usually requires fine mesh and special assumption to capture the free surface behavior. In our proposed method, because we employ the Lagrangian description to the fluid domain, the position of the discrete particles of fluid can be easily tracked by the fluid particles. Therefore, the fluid-solid interface and the free surface of fluid can be directly obtained. In addition, by separating the virtual pressure from the governing equations, the high order approximations of reproducing kernel particle method can be applied for the density and stress fields, thereby improving the accuracy of the numerical results. We also introduce the pseudo-derivative shape function, to improve the computational efficiency while maintaining the accuracy of the approximation of derivatives. To enforce the stability of the numerical method, we introduce the Stabilized Non-conforming Nodal Integration (SNNI) method to modify the strong form of governing equations. It can suppress the tensile instability and avoid using the artificial viscosity to stabilize the solution. For fluid-solid interaction, the discrete particles on the fluid-solid interface are regarded as fluid particles. By the concept of kernel contact, the interaction force is calculated for the discrete particles in the overlap region of the influence domain. This new method avoids directly application of nodal force and the non-physical boundary treatments such as Penalty Method to ensure the accuracy of numerical results on the coupling regions. The proposed method is first applied to some simple numerical examples to verify the order of approximation and accuracy. Several hydrodynamic problems are used to test the feasibility of proposed method for the fluid simulation. Finally, the examples of fluid-solid coupling simulations are presented. The numerical results are compared with the other researchers’ work to verify the reliability and robustness.