Validation of Potential-Flow Estimation of Interaction Forces Acting upon Ship Hulls in Parallel Motion

The hydrodynamic interaction problem is of great importance for numerical ship handling simulators and at present, only a relatively simple potential double body panel method can be expected to supply estimates of interaction forces and moments in real time on commonly used hardware, without limitations on the hull shape, and on the mutual position and motion of the interacting bodies. Such a code was developed on the basis of the classic Hess and Smith method and proved to be fast enough to model interaction in real time when a moderate number of panels is used. In the present paper, results obtained with the potential code are validated against experimental data obtained in deep and shallow water towing tanks for the case of a tug operating near a larger vessel. All the tests corresponded to the steady regime and only cases with parallel center planes were considered here. The comparisons carried out for various discretization of the hulls provide useful information about natural limitations in breaking at too close lateral distances and about acceptable trade-off between the computational speed and accuracy. In addition, influence of the nonzero sway and yaw velocities is investigated numerically.