Scientists uncover details of seafloor sediment dispersion in the Pacific ocean
Scientists uncover details of seafloor sediment dispersion in the Pacific ocean lead image
On the Pacific’s seafloor, we find many polymetallic nodules containing up to thirty percent manganese. If these polymetallic modules are regularly harvested, the disturbance of the top-layer sediment of the ocean floor may lead to large sediment clouds in the ambient ocean.
A research team from the National University of Singapore has presented a study of the sediment concentration and deposition in the ocean using their own modified version of the Smoothed Particle Hydrodynamics (SPH) model based on a mixture model for two-phase flow. Their modified model incorporated a variety of relevant physical phenomena, such as the hindering effect and sediment deposition/re-suspension on the ocean floor. They report their findings in Physics of Fluids.
The researchers set their simulations with an opened boundary domain with a unidirectional underlined current that is subject to appropriate boundary conditions for deposition and dispersion on the seafloor. Their simulation exercise demonstrated sediment spreading along the seafloor primarily driven by current convection, turbulent diffusion and density. The team assessed that current convection is the main factor for influencing sediment dispersion from a far distance, while the density-driven flows are more dominant nearer the source.
“Sediment dispersion and sediment deposition in the ocean are two phenomena occurring in very much different length scales and time scales,” co-author Thien Tran-Duc explained. “Thus, modelling them by a single model is very challenging.”
In fact, because this study simulates such a complex problem, the study is ongoing. Thien says the team hopes that in the future, the data collected can be used to minimize the environmental impact of polymetallic nodule harvesting.
Source: “A smoothed particle hydrodynamics (SPH) study of sediment dispersion on the seafloor,” by Thien Tran-Duc, Nhan Phan-Thien, and Boo Cheong Khoo, Physics of Fluids (2017). The article can be accessed at https://doi.org/10.1063/1.4993474 .
