短波中船舶增加阻力之探討

Abstract

本研究應用計算流體力學套裝軟體FLUENT，以Wigley hull為計算船型，模擬船舶因短波波浪所造成的增加阻力（added resistance）。在非穩態流場的設置下，模擬出三維的不同波長船長比之短波波浪，進而放入船體在非穩態波浪中求得船體受到短波波浪之平均阻力，而該阻力值包含因入流速所產生之靜水中穩態阻力，以及波浪增加阻力。因此，數值模擬尚需包含船體在三維穩態流速中之船體阻力模擬，求出穩態靜水中阻力，將暫態波浪模擬計算所得之平均阻力減去穩態靜水中阻力值，即求出短波波浪因反射所引致的增加阻力。 藉此CFD計算結果，參考日本造船學會發表之論文，做進一步的比對探討與分析，結果顯示本研究的數值計算顯示定性及定量上合理的趨勢。在此基礎上，期望後續能進行更加精確的波浪增加阻力的非穩態模擬，模擬更接近實體船型及實際海況的波浪增加阻力，以CFD作為替代水槽試驗之波浪增加阻力預估工具。

In this study, we apply the Computational Fluid Dynamics package software FLUENT to simulate the added resistance of Wigley hull in short waves. Firstly, short waves of three different wave lengths in a tank were generated numerically. Then the model of Wigley hull was set in the wave tank, and force acting on the hull was simulated and the average resistance was obtained. In addition, Wigley hull in the tank of uniform flow was also simulated, and the resistance in calm water was also calculated. Then the difference between the resistance in calm water and the average resistance in waves of these three different wave lengths, i.e. the added resistance in short waves, were obtained. The simulated results were compared with the existing data of published references. The trends of added resistance vs wave length are quite similar to those of published data, qualitatively and quantitatively. The validity is confirmed to apply the CFD tool of FLUENT to predict the added resistance of a ship in short waves.