Numerical simulation of sediment transport by thermohaline bottom currents

Numerical simulation of sediment transport by thermohaline bottom currents

We speculated about how the case study presented by Miramontes et al. 2020 could be represented numerically in order to understand the solid transport mechanisms associated with the interaction between turbiditic and contouritic currents. Turbidity currents are dense, bottom currents caused by the downflow of sediments into the sea, carried across the continental slope, by gravity, to the sea bottom. The contour currents are characterized by very low geostrophic velocities and are related to geostrophic bottom currents on the bottom. Currently we did not find such typology of analysis in literature and there are criticalities about how to represent the phenomenon with a pertinent computational domain. We will analyze the two types of currents (turbidity and contour) at first independently, using the reference literature for comparison (Kyrousi et al. 2018, Falcini et al. 2018). This will be useful to better understand the critical characteristics of the two currents, and the possible problems posed by their interaction.

With this project we aim to better understand the mechanism of sedimentation resulting from the interaction between turbidity and contour currents. Furthermore, the complexity of this kind of simulations will allow to test the computational capacity of a new High Performing Computing network, developed by the Terabit project.

For the complexity and the non-stationarity of the problem the simulation could be done with: -Motion field solved with a Large Eddy Simulation -Solid transport with a Eulerian approach, using a transport equation for a scalar (with a two-way coupling with the eq. of motion via the buoyancy term), considering a decay term related to the settling velocity of the sediment (ws = velocity at which the acceleration of the particle is zero, so it is close to having constant velocity) (Kyrousi et al. 2018). The computational cost would be very high (Inghilesi et al. 2018), so the simulation could be useful for testing the Terabit network, in line with one of the main goals of the doctoral program.