Ye Tao

• Hydrothermal plumes form along mid-ocean ridges where seawater exchanges heat and chemical components with the hot rock and is injected back into the ocean as hot, mineral-rich and buoyant fluid. We take a numerical modeling approach to study the dynamics of hydrothermal plumes with the 3D time-dependent, Eulerian, adaptive mesh refinement code {\sc Gerris}. We have implemented a new module into Gerris that treats buoyancy-driven turbulence by means of a subgrid mode. First we simulate hydrothermal plumes in a static environment and the entrainment coefficient that we deduce from simulations falls into the range of the experimentally determined values, but the ratio between the level of the neutral buoyancy and the maximum plume height are found to be higher than the one predicted by the integral models. This difference will lead to a substantially different heat flux estimation. We also measure the radial profile of the plume and calculate the concentration-to-velocity width ratio which agrees very well with the laboratory measured value. Then we explore the importance of background currents and find a similar difference between the 3D simulations and integral models over the rising height, just as the static case. We further prove that a significant fraction of this difference can be explained by the ignorance of the turbulent transport of the latter. Clustered vents appear in many hydrothermal systems. We simulate systems with different clustering configurations to study the effects of clustering. In addition to studying the far field properties of hydrothermal plumes such as the rising height, we implement a near-field numerical experiment to simulate and validate a speed meter device used in in-situ hydrothermal volume flux measurement and find it needs correction when applied to high temperature plumes. In the end we implement an artificial reaction between plume fluid and seawater with a virtual reaction rate and investigate the dependence of reaction intensity on the fluid concentration and mixing. Our high resolution simulations provide a reliable and also flexible modeling approach to model the hydrothermal plumes in complicated environment with the potential to cooperate with the state of the art field researches.