International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The objective of the simulations is to calculate the total resistance and visualize the flow around a bare hull of a boat motion in deep and shallow water. Ship resistance is an important issue for ensuring smooth propulsion in various speeds in open sea and especially in the increasing influence of shallowness. Subcritical speed range in open shallow water is the main interest regime. A limited number of cases in critical and supercritical speed regions are applied in computations for comparison. For the full-scale bare ship-shape body resistance tests, computational fluid dynamics techniques and SST k-omega turbulence viscous model were employed. All calculations were carried out considering the influence of the free surface effect in a fluid. For convenience of mesh generation, an automated structured polyhedral meshing was adopted for the delicate curved surface and the domain. CFD solver interFoam – OpenFOAM, is applied to execute all computations in this article. The numerical model was initially built in FreeCAD, an open computer aided design (CAD) software and discretized in the cfMesh, a library implemented on top of the OpenFOAM framework. Post-processing is performed within ParaView, an application for scientific visualization. All software is free.

The prediction of maneuverability is a classic problem in ship hydrodynamics. Likewise, ship motions in restricted waters have been studied for a long time. It is an indisputable fact that full-scale or model tests of the respective ship meet IMO requirements and provide the necessary information for the maneuverability of the ship in deep unconfined waters. However, they are unable to provide practical insight into understanding of ship maneuverability in shallow water, as the maneuvering behavior of a ship in such areas differs significantly. Ship maneuvering in coastal areas and harbor approaches, where space is limited, movement speeds are low, and traffic heavier requires deeper researching. The aim of the present work is to predict the hydrodynamic derivatives in the mathematical model of the maneuvering of ship in shallow waters based on CFD programs with free access like FreeCAD, OpenFOAM and ParaView.
The sequence of solving the task is described with details in this work:
1. Generating the shape of the studied body 2. Creating the domains around the experimental body, sizes and boundaries
3. Defining the continuum, areas and subareas of study, and boundary conditions 4. Generation of the computational grid
5. Defining the continuum – physical models 6. Selection of the calculation algorithm 7. Substances modeling 8. Motion modeling.
9. Modeling of currents and energy 10. Flow turbulence modeling.
Results have been obtained for the linear hydrodynamic derivatives in the mathematical model for the maneuvering motion of a ship.
They are compared with available experimental and theoretical data in the literature.