摘要
本研究應用曲面相交的方法判斷船體在波浪運動中瞬時近似水線。在已知瞬時的水線下，可以獲得船體在水線下的形狀和其NURBS參數資訊。輔以Hyper tangent函數的特性可以快速地在船體浸水曲面上建立網格並節省網格產生所花費的大量時間。藉由定義船體在瞬時波形下的浸水區域來修正在三維空間中船體表面上的壓力與法向量的變化，提升流體動力係數的精確度並奠定未來時程領域下的計算基礎。
本研究首先簡單地以尋找水線的方式切割出四分之一球體，並藉由球體的浸水面積與體積之計算來驗證網格劃分的準確性。船體在靜水面與不同正弦波下的各種浸水面的計算結果來與Rihno軟體的數值加以比較驗證。除此之外，本研究建立的網格也利用船體運動之結果來做分析比較。結果顯示本文所使用的方法，除了在特殊區域外(如:球艏，需要在未來作進一步的研究)，其餘的部分在流體靜力與流體動力計算下都有不錯的數值。

ABSTRACT
The present research applies the Surface-to-Surface Intersection Method to decide the instantaneous approximated waterline for the ship moving in waves. Having the instantaneous waterline, we could obtain the ship underwater hull shape and its NURBS parameters. Incorporated with Hyper Tangent functions, we can build up the mesh on the wetted hull surface very fast and save much time on the mesh generation. We can also define the ship wetted surface under the instantaneous wave form to correct the changes of the pressure and normal vector on the hull surface in three dimensional analysis which can improve the accuracy of the calculations of the hydrodynamic coefficients and offer the better basis in the future time-domain analysis.
In the research, we firstly use the similar way of finding the waterline to cut a sphere quarterly to investigate the accuracy of the mesh generation method developed here through the calculations of the sphere wetted surface area and volume. The calculation results of the ship hull wetted surface are also compared with those obtained from the commercial CAD software Rihno based on the cases in calm water and in sinuous waves. Besides, the motion analysis based on the present mesh generation method is also made in the study. The general results show that the technique developed in the present study can indeed obtain quite good results either in hydrostatic or in hydrodynamic calculations except some special region, e.g. bulbous bow, which needs further study in the future.

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