Hydrodynamic design of deep ocean water discharge for the creation of a nutrient-rich plume in the South China Sea

Abstract

Open ocean mariculture can be established by the artificial upwelling of deep ocean water (DOW). However, one of the major obstacles is the difficulty of containing a nutrient-rich DOW plume without significant dilution. In this paper, the hydrodynamic design of DOW discharge for the creation of the DOW plume in the South China Sea (SCS) is presented. The trajectory and DOW concentration of the plume in a stratified ocean environment where a sharp density interface exists is investigated relative to the current speed, pumped water flow rate, pipe diameter and optimal depth of DOW discharge. A mathematical model is presented to ensure that a desirable nutrient concentration in the DOW plume can be maintained under specific ocean stratification and current conditions. The validity of the mathematical model is verified by a computational fluid dynamics (CFD) analysis on the flow and nutrient transport of the DOW plume. The results show that the volume concentration of DOW in the plume can be controlled by setting up the flow rate, pipe diameter and corresponding optimal DOW discharge depth. In this way, the nutrient-rich DOW plume can be sustained in the open ocean to stimulate marine primary productivity.