| 摘要: |
| 本文以冲绳海槽伊平屋北部热液区（126°53.80'，27°45.50'）的现场水文数据作为背景条件，使用k-ε湍流模型模拟热液柱的动力过程。模拟计算得到的羽流速度、温度和湍流耗散率等基本物理量展现了热液柱的时空演化过程。模拟结果显示，羽流最大上升高度及中性浮力面高度与海底的距离分别为83.62m和68.97m，和2014年先导专项在此附近热液区所观测的温度异常和盐度异常的深度位置（离海底约66—86m）接近。羽流的上升速度满足高斯分布，其半径b与距喷口高度z-H成正比：b=0.0985（z-H），其中z为距海底高度，H为热液烟囱体的高度。羽流的最大体积通量比喷口的初始值增加了878倍，达1.034m3/s；在中性浮力面位置附近，动量通量达到最大值，为0.156m4/s2，比初始值增加了882倍；浮力通量在中性浮力面以下和BM2000（Bloomfield et al，2000）理论模型符合良好，在中性浮力面以上则呈现随高度先增加后减小的特征。本文计算得到的平均卷挟率为α≈0.0807，与背景流较弱的热液区的声学现场观测结果相符。 |
| 关键词: 计算流体动力学 热液柱 动力过程 最大上升高度 卷挟因子 |
| DOI：10.11693/hyhz20170500148 |
| 分类号:P731.21 |
| 基金项目:中国科学院战略性先导科技专项（A类）项目，XDA11030301号；国家自然科学基金项目，41706029号，41406035号，41476167号，41606010号；广东省自然科学基金自由申请项目，2016A030313155号。 |
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| NUMERICAL SIMULATION OF THE DYNAMICAL PROCESSES OF HYDROTHERMAL PLUMES IN OKINAWA TROUGH |
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CEN Xian-Rong, GUO Shuang-Xi, LU Yuan-Zheng, QU Ling, ZHOU Sheng-Qi
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State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology Chinese Academy of Sciences, Guangzhou 510301, China
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| Abstract: |
| We used k-ε turbulence model to simulate the dynamical process in hydrothermal plumes. The hydrography measurements at the Iheya North field (126°53.80', 27°45.50') were taken as the background conditions. The spatial-temporal evolution of the plume was examined in velocity, temperature, and turbulent dissipation. The numerical results show that the maximum rising height and the neutrally buoyant height of the plume is 83.62m and 68.97m, respectively, which is similar to the observational results. The nearby observations conducted in 2014 revealed temperature and salinity anomalies at heights of 66—86m height above seafloor. We found that the rising speed of the plume is characterized by Gaussian distribution, and the radius is proportional to the height above vent [b=0.0985(z-H), where H is the height of the vent chimney. The maximum volume flux is 1.034m3/s, which is 878 times of the initial volume flux at the vent orifice]. The momentum flux reaches its maximum of 0.156m4/s2 (882 times of the initial momentum flux) at the neutrally buoyant height. Above the neutrally buoyant height, the buoyancy flux increases first and then decreases. Below the neutrally buoyant height, the BM2000 model (Bloomfield et al, 2000) showed satisfactory agreements with the present simulation. The mean entrainment coefficient was evaluated as 0.0807, which is in excellent agreement with the result from acoustic measurements in the hydrothermal field with weak background flow. |
| Key words: computational fluid dynamics hydrothermal plumes dynamical process maximum rising height entrainment coefficient |
