An efficient approach to CFD simulations with small ships maneuvering in the wave field of larger ships via optimized forcing zones

The maneuvering of small ships within the wave field of larger ships is a common application in practical ship hydrodynamics. Examples include optimization of launch and recovery operations regarding ship motions, interaction between a tugboat and a cargo ship, or the safe approach of a patrol boat to a larger vessel. Due to the pronounced scale disparity between vessels, such operations are difficult to realize in wave-tank experiments. Computational fluid dynamics (CFD) simulations of such operations are challenging due to the comparatively large computational effort: The larger ship requires a comparatively large domain, while the smaller ship may require finer mesh resolution and time steps. The present work proposes an efficient approach to perform CFD simulations for such applications. By using forcing zones with optimized coefficients, the size of the computational domain can be reduced to the vicinity of the small ship, and the flow near the domain boundaries is forced towards the wave field solution of the larger ship. This corresponds to a one-way coupling approach, in which the larger ship is not affected by the small ship. The flow fields near the large ship are extracted from a CFD simulation. In the present study, the large ship is moving with constant speed in calm water, and the converged wave field solution is stored and used to define the boundary conditions for the CFD simulation with the small ship. An overtaking maneuver of the small ship is investigated. The resulting ship motions match closely with those of a simulation conducted for the two vessels in a single simulation domain. The proposed approach reduces computational cost by up to 87%. Therefore, the approach is particularly suitable when studying the effects of different ship maneuvers in the same wave fields, as in the aforementioned applications.

Subjects

ship-ship interaction

computational fluid dynamics (CFD)

planing hull

forcing zones

maneuvering

DDC Class

627: Hydraulic Engineering

Publication version

publishedVersion

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An efficient approach to CFD simulations with small ships maneuvering in the wave field of larger ships via optimized forcing zones