Turbulent properties of a deep-sea hydrothermal plume in a time-variable cross flow using anisotropic mixing parameterizations in LES

A large eddy simulation of a deep-sea hydrothermal plume in a time-variable cross flow, parameterized with anisotropic eddy viscosities and diffusivities, is developed to simulate turbulent flow characteristics. The turbulent dissipation rates for kinetic energy (ε) and thermal variance (ε_θ) is approximated by computing the Reynolds averaged sub-grid scale turbulent production from shear and buoyancy (ε=P-B) and from temperature fluxes (ε_θ=P_θ) respectively. The model is tuned to represent the mean flow and turbulent observations of the hydrothermal plume properties at Dante within the Main Endeavour vent field (MEF) at the Endeavour segment of the Juan de Fuca Ridge using specialized acoustic instrumentation. The model takes into account realistic background stratification, and vent exit fluid heat and flow transport. The turbulent kinetic energy and thermal dissipation rates reach their maximum near the vent. Shear production dominates over buoyancy production of turbulent kinetic energy. The model is used to derive several important scalings with cross flows that are relevant to understanding plume impact on the ocean. These scalings include maximum plume rise height and turbulent diffusivity and their variability with cross flow speeds.