Journal of Tropical Oceanography >
Numerical simulation of diffusive convection staircase
Received date: 2018-03-19
Request revised date: 2018-05-22
Online published: 2019-01-16
Supported by
National Natural Science Foundation of China (11547037, 11604181, 41706029, 41776033)
Natural Science Foundation of Guangdong Province (2016A030311042, 2016A030313155)
Open Project Program of the State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology Chinese Academy of Sciences)(LTO1710)
Copyright
Diffusive convection driven by temperature and salinity is a ubiquitous phenomenon in the mid and high latitudes of the ocean. Numerical simulation of diffusive convection can be used to study small-scale dynamic processes of the ocean. In this study, we analyze the formation mechanism of diffusive convection and establish a two-dimensional cavity model. The governing equation of the model is solved by the finite volume method, and the process of layering phenomenon is simulated numerically. The temporal evolution of temperature and salinity of the flow field is given, and the vortex structure of the velocity field is simulated. The processes of the formation and merging of diffusive convection staircases are analyzed, and a theoretical explanation for mass and energy transport processes is given. In addition, the diffusive convection under different heat flux density is discussed. It is found that the growth rate of diffusive convection staircases increases with the increase of heat flux density, and the cooling from the upper boundary plays an important role in accelerating its growth. The variation of heat flux density does not have a significant impact on the evolution of diffusive convection staircases.
Key words: diffusive convection; numerical simulation; salinity; temperature
XU Yan , LIU Xiangquan , SONG Rengang , CEN Xianrong , GUO Shuangxi , ZHOU Shengqi . Numerical simulation of diffusive convection staircase[J]. Journal of Tropical Oceanography, 2019 , 38(1) : 11 -18 . DOI: 10.11978/2018028
Fig. 1 Thermal staircases in the Arctic Ocean (a), and illustration of formation mechanism of diffusive convection (b)图1 扩散对流a. 北冰洋的温度台阶结构(Neal et al, 1969)。图中的矩形阴影表示需要放大后才能观察到温度台阶结构的剖面, 圆环表示温度台阶界面的双层结构。图的左下横轴(双箭头线)的长度表示温度的涨落幅度; b. 扩散对流形成机制示意图 |
Fig. 2 Numerical model of diffusive convection图2 扩散对流数值模型 |
Fig. 3 Distribution of simulated salinity field in diffusive convection at different characteristic stages图3 扩散对流模拟不同特征时刻的盐度分布图 |
Fig. 4 Salinity distribution after 1.392 h in diffusive convection simulation: (a) contour plot, and (b) line plot图4 扩散对流模拟1.392h后盐度状态图a. 等值线图; b. 曲线图 |
Fig. 5 Same as |
Fig. 6 Same as |
Fig. 7 Vector plot of simulated velocity field: (a) 4.811 h, and (b) 17.106 h图7 流场速度分布矢量图a. 4.811 h时; b. 17.106 h时 |
Fig. 8 Comparison of simulated diffusive convection results with different heat flux intensities at the boundary图8 不同热流密度下扩散对流温盐台阶结构模拟结果对比 |
Fig. 9 Salinity distribution after 2.764 h in diffusive convection simulation of case 4: (a) contour plot, and (b) line plot图9 情况④扩散对流模拟2.764h后盐度状态图a. 等值线图; b. 曲线图 |
The authors have declared that no competing interests exist.
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