Forces acting on hydrofoil shapes in natural mud conditions
Verbeke, A. (2022). Forces acting on hydrofoil shapes in natural mud conditions. MSc Thesis. Ghent University, Faculty of Engineering and Architecture: Ghent. xv, 126 pp.
The manoeuvring behaviour of vessels can drastically be influenced when sailing above a sediment layer. Given the increase in computational power over the last decades, this influence is often assessed through computational methods nowadays. The complex mud rheology and behaviour are currently not fully implemented in existing numerical software, so previous research applied simple viscosity models to model the mud. This thesis aims to compare several viscosity formulations based on the force generation of a hydrofoil towed through mud. A numerical approach is used in which the complex three-phase flow is simplified to a two-phase flow. By simulating a one-phase flow, the effect of viscosity formulation on the frictional and viscous pressure resistance is investigated. It is concluded that the effect of the viscosity formulation depends on the local flow field. Hence, the largest differences are found at elevated speeds. Also the inclusion of an interface affects the hydrofoil boundary layer. Throughout the simulations, it became apparent that the turbulence formulation is an important influence for the hydrofoil forces. Also the input parameters and micro-structural description of the fluid mud should be taken into account. In addition, mixing of water and mud, which occurs at low under-keel clearances, needs appropriate modelling. From the results in this thesis, it is clear that a new numerical solver needs to be developed.
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