Session: 12-01-01 Hydrodynamics, Seakeeping and Global Performance

Paper Number: 78413

78413 - Validation of Time Domain Seakeeping Computations Based on Capsizing Model Tests in Natural Seaways 

The design engineer aims to plan a ship that it is able to meet all of its operational requirements. This also includes ensuring that the ship is seaworthy and sufficiently stable in regard to large roll motions even in harsh conditions.  For the study of ship motions in seaways it is essential to examine the seakeeping behavior in short crested, irregular seas, because such seaways include transverse components, which provide the necessary disturbances that may initiate large roll motions. Therefore, in the past capsizing model tests with free-running self-propelled ship models were carried out on large lakes and in bay areas, since here model-scale natural sea states were present and long test runs were also possible, as is usually not the case in a model testing facility. These model tests in model-scale natural seaways have proven to be extremely useful for assessing the intact ship’s vulnerability in seaways and have strongly aided in the observation of the various main phenomena leading to capsizing. With today’s modern measurement technology, such tests can be carried out and evaluated even more precisely in the future. For the design engineer, however, it would be advantageous to be able to assess the ship’s seakeeping behavior already in the early design stage. Therefore, it is useful to review existing design-stage-suitable numerical seakeeping simulation methods by further validation of the simulated data against the historical model test data. To this end, numerical seakeeping simulations are performed using the nonlinear, potential flow theory-based seakeeping code E4-ROLLS, which allows the efficient computation of time series of ship motions in irregular, short-crested seas and thus is a fast and robust method for analyzing ship motions in heavy weather.

The numerical results confirm the seakeeping behavior including capsizing, which was observed and documented in the historical model tests in natural seaways. The utilized numerical method thus enables accurate and exceptionally fast time-domain seakeeping simulations and a high-quality prediction of a ship’s seakeeping ability in harsh environmental conditions. Thus, this paper presents further validation of the numerical method E4-ROLLS and shows that it is possible to reproduce the results of extensive empirical testing in model-scale harsh natural seaway conditions via fast and efficient simulation with the utilized numerical method without sacrificing quality of results.

The paper is original and for the first time presented in public.

Presenting Author: Wiebke Römhild Hamburg University of Technology

Authors:

Stefan Krüger Hamburg University of Technology
Wiebke Römhild Hamburg University of Technology
Philipp Russell Marinearsenal
Christian Frühling thyssenkrupp Marine Systems GmbH