区域化台风波浪现报模式之研究.PDFVIP

摘要 應用 SWAN 波浪模式推算波浪變化，在風浪成長的模擬過程， 出現高估高頻能量及低估低頻能量的現象，導至週期低估。本研究探 討波浪模式的原函數之各項能量變化，發現白沫消散項採用平均尖銳 度來決定波浪是否消散是導致高頻與低頻能量不合理的消散的主 因，因此本研究利用 Alves Banner(2000 、2002 、2003)所提出之飽 和形態消散項來取代原本之消散項，其概念為依據各個成分份波的尖 銳度是否超過一破碎門檻來決定消散與否，但 Alves Banner的經驗 式不考慮水深的效應，無法直接應用在 SWAN 波浪模式，故透過 Jacobian轉換與分散關係式加入水深的效應，以避免波浪傳遞至近岸 時受淺化影響產生不合理的消散。再利用實測資料配合數值的測試來 率定參數，以獲得適合於台灣海域之參數，最後由驗證結果顯示，採 用新的消散項能改善高頻高估與低頻低估的現象，並獲得較好的波浪 週期推算結果。 ABSTRACT This study adopts SWAN wave model for wave simulation of Taiwan water. Simulation results show that the wave period estimations are always underestimated. In order to overcome this predicament, we change different kind of source terms and parameters involved in SWAN wave model. However, it still can not obtain more precise results. With the further discussion we found the unaccuracy results might be induced by the unreasonable wave dissipation rate. Because the overall steepness involved in dissipation term, it might induce too less dissipated energy in high frequency and too more in low frequency, respectively. This condition especially occur in wave energy distributed widely within frequency bands. This study adopted a new dissipation formula based on individual steepness parameter into SWAN wave model. With the disscusion and verification, it can obtain more precise wave period es