매크로 요소 기술에 근거한 격자 변형

Abstract

Recently, a new tidal stream generator has been developed by using flapping motions which are observed in marine animal’s swimming. The flapper can be also deformed in span-wise as well as chord-wise directions in addition to the large flapping motion. In order to analyze the performance of the power extraction, computational fluid dynamic simulations have been utilized however, grid deformation for the large motion and deformation is a big challenging issue. The grid deformation algorithms can be classified into linear algebra methods, elasticity-based approaches, and their hybrid forms. The methods in the first category have advantages in efficiency, but do not normally produce grids of sufficient quality. A spring analogy in the second category is known to cause grid irregularity for the large moving boundary problem and methods for improving the robustness of the grid regularity are subsequently required. The finite element method in the same category provides better quality than simple interpolation schemes, but become too expensive for large grids. Hybrid method using the macro-finite elements and interpolation reduced not only computational cost for finite element solution over entire grid, but also the disparity of mesh size, which causes bad effect on the grid quality. However, the hybrid scheme is still needed to be improved for the flapping tidal stream generator, which has t flapping motion. In order to analyze the performance of the power extraction, computational fluid dynamic simulations have been utilized however, grid deformation for the large motion and deformation is a big challenging issue. The grid deformation algorithms can be classified into linear algebra methods, elasticity-based approaches, and their hybrid forms. The methods in the first category have advantages in efficiency, but do not normally produce grids of sufficient quality. A spring analogy in the second category is known to cause grid ir