| 摘要: | 海嘯對於人類之危害主要在於近岸之能量釋放，並以動量形態展現，因此若僅專注於海嘯波高將不利於海嘯災害之研究。另一方面，當強烈海嘯過後，往往在沙灘上留下公尺等級之海嘯石，例如2004 年南亞海嘯發生後遍佈於Pakarang Cape, Thailand 之海嘯石。海嘯石原本隱沒於水中，由於受到海嘯力之推移而停留於岸邊。因此若能掌握海嘯石的運動模式，便能重現海嘯發生時之衝擊力強度。而海嘯石若未受其他外力干擾而移動，則可用於研究史前海嘯。由於海嘯之推進力與雷諾數有關，因此不利於實驗室之縮小尺寸研究。而其複雜之影響因子導致理論解難以求得。因此，直接求解三維動量方程式為最佳手段。然而該法必須同時求解水、空氣、以及海嘯石移動，加以及龐大計算量之需求，因此至今尚無文獻有能力採用三維計算法研究海嘯石之運動。本研究將以今年所發展之三維多相流流固耦合模式為基礎，模擬海嘯石之移動過程，並以小型實驗驗證數值模式之準確性。對於海嘯力與海嘯石之交互作用方面，本研究將採用多相流模式描述水、空氣、及底泥之運動。透移動固體法與DEM 離散元素模式結合，精確計算固體之運動過程。並採用平行計算，以應付龐大之計算量。由於本研究方法為學界首創，其結果將為世界唯一，預期將有可觀之研究成果。 The destructive power of tsunami is coming from the dissipation of wave energy in the near shore region. The dissipation mechanism transfers wave energy into momentum, which is unable to be described solely by wave height. On the other hand, after the tsunami event, often the tsunami boulders can be seen on the beach. One example is the thousands of tsunami boulders all over the Pakarang Cape, Thailand after the 2004 Indian Ocean Tsunami event. Tsunami boulders are originally submerged in the water, and are transported to the beach area by the tsunami force. If the transport process can be understood, one can reproduce the tsunami intensity. If the tsunami boulders are not moved by other forces, it can be used to study the pre-historical tsunami. Because the tsunami force is a function of Reynolds number, it is not proper to be studied by means of the down-scaling laboratory experiments. Moreover, due to the involvement of many physical variables, analytical solution is rare. The best way to study the transport of tsunami boulders is solving the 3D momentum equation. However, solving 3D momentum equation indicates that the movements of water, air and solid boulders have to be solved at the same time with massive computational load; which hasn’t been implemented to date. In this study, we will adopt the 3D numerical model developed this year to simulate the movement of the tsunami boulders. A laboratory experiment will be performed for the model validation. As for the interaction between the tsunami force and tsunami boulders, the multi-phase model will used to solve the dynamics of water, air, and mud. The moving solid method will be combined with the DEM model to predict the boulder movement accurately. In order to cover up the heavy computational requirement for the real case simulation, the parallel computing will be adopted. Because this is the first 3D numerical model used to solve the tsunami boulder problems, a fruitful research result is expected. 研究期間：9908 ~ 10007 |
