Interest in deep sea mining (DSM) has increased significantly due to mainly an expected increase in consumption of rare metals and a trend towards a green world. The supply of rare metals is not always reliable, since there is a limited number of major suppliers. An alternative source to the established suppliers on land could be polymetallic nodules found in deposits on the abyssal plains of the oceans.
These nodules contain multiple metals such as nickel, cobalt and rare earth elements and can be extracted by a Seafloor Mining Tool (SMT). As a consequence of the collection of the nodules the SMT erodes the sediment bed as well. The hydraulic collection method of the SMT in this thesis makes use of the Coandă-effect. It is desirable to reduce the amount of sediment picked up from the bed by the collector head of the SMT, as this ultimately reduces the potential disturbance of benthic life by turbidity flows.

Water entrainment of ambient water in front of the collector head and spillage flow behind the collector head caused by the Coandă-effect is also not fully understood, suggesting a deeper understanding of the flow field around the collector head is required.
Operational parameters of the SMT and a secondary jet of the collector head have influence on the flow field and thereby the amount of sediment picked-up from the seabed. The influence of these parameters on bed erosion and sediment collection by the SMT and spillage behind the collector head requires further investigation as well.

To this end Computational Fluid Dynamics (CFD) is used to conduct simulations on the DelftBlue supercomputer at the Delft High-Performance Computing Center. The OpenFOAM solver driftFluxFoam is modified in order to investigate the collector head of a Coandă-Effect-based SMT. In these simulations a small-scale and full-scale collector head is investigated with the focus on the flow field behaviour, sediment collection and spillage. Additionally for the full-scale collector head the influence of 4 collector head parameters and 2 sediment bed parameters on the collected and spilled sediment is investigated.

The results show that the flow field around the collector head of the Coandă-Effect-based SMT is in agreement with previous research. Jet flow dominates near the curved plates due to the Coandă-effect, Water is entrainment in front of the collector head and sediment is eroded and either collected or spilled behind the collector head.
The variation of the 6 parameters have influence on bed erosion, sediment collection and spillage as expected, especially the jet flow through the main and secondary jet. Additionally, the amount of collected and spilled sediment is increased by an increased collection duct flow and decreased by an increased forward velocity. The importance of a balanced combination of the parameters and the influence of the sediment characteristics is also stressed.
The novelty of a secondary jet in the collector head has influence on the sediment collection and spillage as well when the flow rate is varied, suggesting that this can be used in the collector head design to reduce the entrainment of water and thus further reduce the amount of bed mobilization, sediment collected into the SMT and sediment spilled behind the collector head reducing the environmental pressure.