The Seakeeping Committee Final report and recommendations to the - PDF document

Proceedings of 25th ITTC – Volume I 209 The Seakeeping Committee Final report and recommendations to the 25th ITTC Four committee meetings were held at: 1. GENERAL QinetiQ Ltd, Gosport, United Kingdom, � 1.1 Membership and meetings January 2006 Naval Surface Warfare Center, Carderock � The Committee appointed by the 24 th ITTC Division, West Bethesda, USA, October consisted of the following members: 2006 National Technical University of Athens, � Mr. Terrence Applebee (Chairman), Naval � Greece, May 2007 Surface Warfare Center, West Bethesda, Seoul National University, Korea. � USA December 2007 Mr. Paul Crossland (Secretary), QinetiQ � Ltd, Gosport, United Kingdom Recommendations of the 24 th ITTC 1.2 Dr. Gregory Grigoropoulos, National � Technical University of Athens, Greece The following is the specific guidance Mr. Greg Hermanski, Institute for Ocean � provided by the 24 th ITTC Seakeeping Technology, St. John’s, Canada Committee on the work to be undertaken by Dr. Yonghwan Kim, Seoul National � this committee. University, Korea 1. Update the state-of-the-art for Dr. Rumen Kishev, Bulgarian Ship � predicting the behaviour of ships in Hydrodynamics Centre. Varna, Bulgaria waves including high speed and Dr. Koichiro Matsumoto, Universal � unconventional vessels, emphasising Shipbuilding Corporation, Kawasaki, developments since the 2005 ITTC Japan Conference, Dr. Jianbo Hua, SSPA Sweden AB, � Göteborg, Sweden a) Comment on the potential impact of Dr. Jinzhu Xia, Australian Maritime � new developments on the ITTC. College, Launceston, Australia b) Emphasise new experimental techniques and extrapolation methods and the practical applications of computational methods to seakeeping Dr Hua resigned during the term of this prediction and scaling. committee and was replaced by Mr. Dariusz c) Identify the need for R&D for Fathi, Marintek, Trondheim, Norway. Dr. Xia improving methods of model changed companies shortly after his experiments, numerical modelling and appointment and was unable to participate on full-scale measurements. the 25 th ITTC Seakeeping Committee.

The Seakeeping Committee 210 2. Update the procedure for experiments committees’ mandates and available expertise on rarely occurring events, 7.5-02-07- such that both organisations could benefit from 02.3. further cooperation, and further collaboration would be advantageous if the participation of 3. Update the procedure 7.5-02-07-02.1 the ITTC Ocean Engineering and ISSC for model tests on linear and weakly Environmental committees is included. non-linear seakeeping phenomena. The main task of the Seakeeping 4. Rewrite the procedure 7.5-02-07-02.2 Committee is the development of new and for added resistance and power increase existing procedures. Examples of existing in irregular waves. ITTC recommended procedures that may be of interest to the ISSC Loads Committee would 5. Update the procedure 7.5-02-07-02.4 include: for the validation of codes in the frequency domain so that it is - Procedure 7.5-02-07-02.1 Seakeeping independent of the method used. Experiments 6. Develop a procedure for the validation - Procedure 7.5-02-07-02.3 Experiments on of codes in the time domain so that it is Rarely Occurring Events independent of the method used. - Procedure 7.5-02-07-02.4 Validation of 7. Support the Specialist Committee on Seakeeping Computer Codes in the Frequency Uncertainty Analysis in reviewing the Domain. procedures handling uncertainty analysis. It may be possible that the Loads committee could review and support the process of 8. Critically review examples of validation updating existing procedures and participate in of prediction techniques. Identify and development of new ones. specify requirements for new benchmark data. Benchmarking and comparative studies were identified as a possible form of joint 9. Determine requirements for benchmark activities to the extent that both committees tests for seakeeping in oblique waves could share resources to conduct future joint such that these benchmark tests could benchmark and comparative studies. As part of be conducted in the future. its work the 25 th ITTC Seakeeping Committee undertook a task to propose defined 1.3 Cooperation with the ISSC requirements for suitable benchmark tests, including information required for the data to The importance of cooperation with the be qualified for inclusion in the ITTC International Ship and Offshore Structure benchmark database. The Seakeeping Congress organisation, specifically, the I.2 Committee consulted the ISSC Loads Loads Technical Committees, was recognised Committee on the proposed final description. by arranging a Joint meeting at the National The ISSC Loads Committee invited ITTC Technical University of Athens in May 2007. member organisations (members of the The meeting underlined the importance and Seakeeping committee) to participate in a benefits of the inter-committee collaboration planned comparative study to calculate lateral with communication between committee bending and torsion moments using the various members being recognised as the most basic numerical tools available to members of both and important form of contact and information committees. exchange. There was a clear overlap in both

Proceedings of 25th ITTC – Volume I 211 The ISSC takes place a year later than the of generated waves in existing and new ITTC and thus the phasing of reports from one experimental facilities. Existing and newly committee is not convenient for the other. developed theories and codes are being used However, both committees would benefit from for that purposes. the exchange of the list of references from their respective state-of-the-art reviews. ISSC has Naito at el . (2005) presents a theory of ship forwarded a copy of the 2006 ISSC Loads motion analysis of tests conducted in ring report complete with written discussion and waves and focused transient wave generated by response. It may be possible for committees to an energy absorbing wave maker in a compact review each other reports before their circular wave basin. The ring waves are respective Conference submissions but this described as multidirectional waves composed requires further discussion with the of incident waves with the same amplitude and committee’s respective parent organisations. A period arriving from all directions. The Joint report could also be considered feasible in resultant motions are representing the linear the future, however, for the time being such a summation of responses to individual incident task might be regarded as premature. waves that compose the ring waves. The directional ship characteristic can be obtained For future collaboration some form of in a single run. continuity amongst the two committees should be ensured; past experience has shown that Naito (2006) reviews theories of wave opportunities for collaboration between both generation and absorption and investigates the organisations can be lost due to lack of development of a high-performance absorbing continuity in contacts and/or communication. wave-maker for generation of both angular and Thus, the following is proposed to help irregular waves in model test facilities. He also maintain the continuity of the collaboration: contemplates various configurations of wave- tanks to optimise their performance. - Common membership. Both parent Generation of waves in a traditional rectangular organisations should assure that the relevant basin can be questionable because of problem committees will share at least one common of reflected waves from the basin walls. The member who could act as a liaison between the author proposes a concept with an absorbing two committees. The phasing in the ITTC and wave-maker around the tank simultaneously ISSC can be utilised to ensure appointment of absorbing undesirable waves and generating such a common member. required waves. Such a tank and wave-maker concepts are described as the Advanced - Scheduled joint meetings. Propose that the Multiple Organized Experimental Basin second (or 3 rd ) ITTC meeting and the first (AMOEBA) and Element-Absorbing Wave- ISSC meeting of their respective committees maker (EAW) respectively. Generated become permanently scheduled as a joint examples of snapshots of wave amplitudes and committee meeting. long-crested narrow-banded irregular waves show promising results. 2. REVIEW OF STATE-OF-THE-ART Bonnefoy et al. (2006a) presents the first of two papers reporting on the development and 2.1 Developments in Experimental validation of a 3D second order numerical Techniques wave tank model. The authors present, in Part A, the fully spectral time domain formulation. New and improved concepts of wave An extensive verification study of the model making amenities are being considered to accuracy and convergence properties is enhance model testing efficiency and accuracy reported in the context of both local and global