Convective instability-induced mixing and its parameterization using large eddy simulation. (May 2019)

• Record Type: Journal Article
• Authors: Gao, Xiaoqian; Dong, Changming; Liang, Junhong; Yang, Jingsong; Li, Guojing; Wang, Dongxiao; McWilliams, James C.
• Is Part Of: Ocean modelling. Volume 137(2019)
• Page Start: 40
• Page End: 51
• Publication Date: 2019-05
• Subjects: Convective mixing -- Large eddy simulation -- Hydrothermal plume -- Parameterization; Oceanography -- Periodicals; Océanographie -- Périodiques; Oceanography; Periodicals; 551.46
• DOI: 10.1016/j.ocemod.2019.03.008
• Languages: English
• ISSNs: 1463-5003

Abstract

Abstract: A large eddy simulation (LES) model is applied to study convective instability processes driven by hydrothermal exhalations. The process of convective mixing induced by a bottom heating source is examined in a stratified and rotating frame. The control case of numerical experiment is configured with the horizontal and vertical resolution 5 m located at 35°S. Its results show that the three-dimensional structure of the hydrothermal plume displays an umbrella shape. A strong clockwise vortex above the vent is present and the axis of the vortex is tilted with organized precession. A series of numerical experiments are conducted to test the sensitivity of three characteristic parameters (eddy viscosity ( K ), maximum plume rise height ( Z max ) and the intensity of the vortex ( I vortex )) to three variables: heat flux from the vent ( HF ), rotation rate ( f ) and background stratification ( N ). Based on the sensitivity experiments, parameterizations of eddy viscosity and maximum plume rise height with respect to HF, f and N are obtained. Highlights: A LES model is applied to study the mixing induced by a hydrothermal plume. A vortex is generated by the rising plume. The vertical axis of the plume is tilted, resulting in an organized precession. A parameterization of the eddy viscosity is obtained. A scaling of the maximum plume rise height is concluded.