BREWEL – Simulation of Ships with Breaking Waves
2023 – 2026

During the design phase, numerical methods are used to determine resistance and optimize the hull lines. Based on this data, a performance prognosis is created, taking into account power reserves. Once the basic design parameters, such as length, width, draft, propulsion unit, etc., are fixed, the construction costs are largely determined. A correct performance prognosis during the design phase is therefore essential for the profitable execution of the project.

The final performance forecast is made after the contract is signed, based on measurements. If the forecast uncertainty of the numerical methods exceeds the considered power reserves, costly measures or penalty clauses are hard to avoid. Therefore, a high level of forecast accuracy is crucial for competitiveness and must be guaranteed to the highest possible extent. For ships with breaking waves, larger discrepancies occur between the calculation results and the measured resistance values. The calculated power values can deviate from the measured values by up to 20%. These values are far outside the usual safety margins and expected ranges. Simulations conducted on other facilities have shown similar deviations. The calculations were performed using different RANSE solvers (Reynolds-averaged Navier-Stokes Equations) and company-specific settings, so a general error in the calculation methods can be assumed. Further investigations have shown that, for example, the trim position can be ruled out as a source of error. The cause of the error is considered to be the wave system with the breaking bow wave. It is assumed that the breaking bow wave is not correctly captured in the simulations, and as a result, the wave interferences between the bow and stern wave systems are also affected. As part of the research topic, the prognosis accuracy for ships with breaking waves is to be improved and integrated into the procedural guidelines of SVA Potsdam. To achieve this, resistance, wave patterns, and wake fields for different ships will be measured and made available for the validation of simulations. The focus of the numerical simulations will be on the necessary grid resolution, the inclusion of surface tension in the simulations, and the identification of differences between homogeneous and heterogeneous multiphase models. The calculations will be conducted using different RANSE solvers and meshing strategies.