海底火山喷发大气冲击波激发的轴对称海啸波数值模型  

NUMERICAL MODEL OF AXISYMMETRIC TSUNAMI WAVES GENERATED BY ATMOSPHERIC PRESSURE SHOCK WAVES OF SUBMARINE VOLCANIC ERUPTION

作　　者：吴蓓蓓 刘桦[1] Wu Beibei;Liu Hua(MOE Key Laboratory of Hydrodynamics,Department of Engineering Mechanics,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学工程力学系,水动力学教育部重点实验室,上海200240

出　　处：《力学学报》2024年第7期2015-2028,共14页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金资助项目(11632012)。

摘　　要：海底火山喷发引发海啸具有多源激发机制,包括水下爆炸、边坡失稳、火山口坍塌、碎屑流、地震以及大气扰动.为了深入认识轴对称移动气压扰动激发海啸的机理,探究气压扰动参数对水波形态的影响规律,本文在柱面孤立波Boussinesq模型的基础上,考虑水面移动气压扰动作用,建立了由火山喷发激发的轴对称移动气压场所驱动的海啸波数值模型.利用不同地形上柱面波的传播算例验证了本模型的精确性与稳定性.数值模拟了2022年汤加火山喷发大气扰动激发海啸事件,并与太平洋DART浮标实测数据比较,较好地复演了大气扰动驱动海啸波的远场传播过程,并讨论了波动在深水区的色散行为.研究了轴对称气压扰动的径向移速、强度及尺度对波动演化特征的影响,结果显示:气压移速与浅水波速的相对大小显著影响波形,当二者接近时将激发Proudman共振.在共振条件下,波幅与径向传播距离呈近似线性增长关系,波幅放大因子随气压尺度增大而减小.在远离共振条件时,气压强度和尺度对波幅放大因子的影响相对较小,受波能流守恒约束柱面自由波幅则沿程衰减,受迫波幅值近似按气压衰减规律变化.Tsunami waves induced by submarine volcanic eruption involve multi-source mechanisms,such as underwater explosions,pyroclastic flows,flank failures,column and caldera collapses,and atmospheric pressure disturbances.Based on the cylindrical Boussinesq equations,a numerical model for tsunami waves driven by axisymmetric motion of atmospheric pressure disturbances is developed to understand how axisymmetric pressure fields lead to tsunami waves and explore how pressure parameters affect water wave patterns.The accuracy and stability of the present model are verified against numerical results of cylindrical wave propagation on different terrains.Furthermore,a numerical simulation of the 2022 Tonga volcanic tsunami event is implemented.The computed wave elevations induced by the atmospheric pressure disturbance from the volcanic eruption agree well with the DART buoy data in the Pacific ocean,which demonstrates the air-water coupling mechanism for the generation and propagation of Tonga tsunamis.The dispersion behavior of tsunami waves in certain regions of the deep ocean is discussed.The effects of the radial velocity,spatial scale,and strength of the pressure disturbance are studied.It turns out that the water wave pattern is strongly related to the radial velocity of pressure.The Proudman resonance is triggered when the pressure velocity approaches the long wave celerity,and the amplitude of the resonant wave grows approximately linearly with respect to radial propagation distance.The amplitude amplification factor decreases with the increase of pressure scale under the resonance condition,while the influence of pressure strength is negligible.In contrast,apart from the resonance condition,there is less influence of both the spatial scale and the strength of the pressure disturbance on the amplitude amplification factor,and the cylindrical free wave amplitude decays with distance due to the wave energy conservation,while the forced wave amplitude varies according to the decay law of pressure disturbances.

关 键 词：移动气压扰动 柱面波 BOUSSINESQ方程 Proudman共振 汤加火山海啸 

分 类 号：O35[理学—流体力学]