Combined semi-analytical and finite element approach for hydro structure interactions during sloshing impacts - "Sloshel project"

Malenica, S., Korobkin, A.A. ORCID:, Ten, I., Gazzola, T., Mravak, Z., De-Lauzon, J. and Scolan, Y.M. (2009) Combined semi-analytical and finite element approach for hydro structure interactions during sloshing impacts - "Sloshel project". In: UNSPECIFIED.

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The paper discusses the development of the combined semianalytical (fluid flow) and numerical FEM (structure) models for hydro structure interactions during the sloshing impacts in the tanks of the membrane type LNG carriers. This is a very challenging problem and lot of work, both experimental and numerical, has been done in the past. However, it is fair to say that no fully consistent solution exists up to now. Indeed, the small model tests, which are usually conducted in this context, suffer from scale effects and numerical CFD calculations suffer from numerous numerical problems and prohibitive CPU time requirements. There is a clear necessity for full scale measurements with the real LNG and the real containment system. Unfortunately this is technically extremely difficult and, up to now, there is no documented work on this, at least not in open literature. In the absence of the real full scale measurements, some "quasi" full scale measurements were performed. These measurements consist in impacting the real containment system structure through the drop tests technique Kim et all (2008), or through the more sophisticated wave generated impacts (Sloshel project - Malenica et al (2009), Brosset et al (2009)). The developments which are discussed in this paper were conducted within the Sloshel project which concentrated on the structural response of the real (full scale) containment system under the breaking wave impacts. Very rich and ambitious project objectives have been defined, with the final goal of improving the current methodologies used in the structural assessment of the containment system and the supporting ship structures. At the beginning of the project, it was decided that the effort in the numerical part would be concentrated on the development of semi-analytical methods for the local fluid flow, which will be combined with the complex structural FEM models for containment systems. The use of the classical CFD methods for the local analysis of extremely complex sloshing phenomena was avoided at the beginning of the project, but was included later. The simplified semi-analytical models for fluid flow, keeping the main physical parameters allow for the assessment of the phenomena within the reasonable computational effort. The drawback is that the impact situations should be highly simplified. In that respect, the sloshing impacts were preliminary classified into 3 main groups: • impact without inclusion of air (steep wave impact), • impact with entrapped air pocket (Bagnold type impact), • impact with aerated fluid. Some intermediate impact types were also identified but they received less attention so far. For each impact type, the dedicated semi-analytical model is developed and the computational results are compared with the full scale Sloshel tests. During the project some additional modeling difficulties arose and one of them is the modeling of the wave propagation which is necessary for proper definition of the main flow parameters just before the impact happens. Different approaches, based on the potential flow modeling of the wave propagation, were proposed by ECM and were shown to be very efficient in the present context. These wave propagation models are also briefly discussed.

Item Type: Conference or Workshop Item (Paper)
Faculty \ School: Faculty of Science > School of Mathematics
Related URLs:
Depositing User: Vishal Gautam
Date Deposited: 18 Mar 2011 10:24
Last Modified: 05 Jan 2023 15:30

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