The Numerical Wave Tank (NWT) group of the International Society for Offshore and Polar Engineering was initiated at the 5th ISOPE conference in The Hague (1995) by Prof. C.H. Kim (Texas A&M University). This group is open freely to everybody interested in this topic. It is aimed at developping links between active researchers in the field of the numerical simulation of free surface waves, their generation and their interaction with solid bodies. The activities of the group will tend to: 1. promote the concept of Numerical Wave Tank in the scientific community, 2. exchange experience between participants in a friendly spirit, exempt from competition attitude, 3. build and maintain a free access data bank on selected benchmarks. At the 6th ISOPE conference in Los Angeles (1996), I was elected by the participants as the group leader for a two years mandate. It is the reason why I author the present report. During the NWT group meeting at the 7th Conference in Honolulu (1997), the concept of Numerical Wave Tank was clarified by the participants. Numerical Wave Tanks are computer codes whose final goal is to reproduce physical wave basins as closely as possible. They must present at least the following features : 1. free-surface flow dominated by gravity in a bounded domain, 2. fully non-linear boundary conditions (free-surface, floating body) 3. simulation in the time-domain , 4. physical wave generation (moving wall or varying pressure) 5. finite constant depth. Extra properties may possibly be accounted for as for instance viscosity, surface tension, sediment transport, wave breaking, current, sediment transport, uneven bottom, sloping beaches, fixed bodies, floating bodies, other modes of generation,... During this 1997 session, it was also decided by the members of the group to begin a series of informal workshop meeting where computational benchmark cases will be defined and their results discussed and commented in a special session during the forthcoming ISOPE conferences. A free access data bank has been created and will be progressively enriched with the numerical results of the participants; this data bank is accessible freely and permanently in an ftp site via Internet. Then everybody can get any of the participants data files and perform his own analysis and comparisons. The files contain not only numerical results, but also a short text section where the numerical technique is summarized and related bibliographic references are listed. The detailed instructions, including data formatting for file submission will be found in the (PostScript) file: ftp://ftp.ec-nantes.fr/NWT/1998/instructions.bench.ps Result files can (still) be sent to A.H. Clement (Ecole Centrale de Nantes-France) via email or FTP. Contributors must form the filename by appending the test case number to their name (or to a pseudo for anonymous contributors). ftp://ftp. ec-nantes.fr/incoming (userid=anonymous ; password= youremail; please notice that for security reasons, you will not "see" the content of the incoming folder) Result files from other contributors can be freely loaded from : ftp://ftp.ec-nantes.fr/NWT/1998/... We consider this benchmark to be permanent, with no deadline at all. So, contributors can still send their files; they will be processed and then put in the data bank to enriched it for future users.
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