Dynamic analysis of a tube bundle with fluid-structure interaction modelling using a homogenisation method

The present paper is concerned with the dynamic analysis of a tube bundle with fluid-structure interaction (FSI) modelling. Modelling of FSI is performed with a homogenisation approach which is compared with the classical coupled approach; this latter is based on a direct finite element discretisation of the coupled problem with all tubes modelling, while the former lies on a description of the fluid-tubes system through an equivalent continuous medium, characterised by a set of dynamic equations which describe the behaviour of the tubes and the fluid from a global point of view. Theoretical background of the method is recalled, numerical implementation in a finite element code is exposed and comparison of the "homogenisation" and "coupled" method is proposed in the case of a 10 x 10 tube bundle, in 2D and 3D configurations. Calculation of eigenmode shapes, frequencies and effective masses with the two methods is performed, as well as the dynamic response of the coupled system subjected to seismic loading. It is concluded that: (i) the computational time are significantly lowered when using the homogenisation method instead of the coupled method, since the problem size is reduced by 90%; (ii) the tube bundle dynamic is described in a space-averaged manner, which is sufficient to account for the main inertial coupling effects: no significant discrepancies are reported in the modal and dynamic analysis, when performed with the homogenisation and the coupled approaches, which makes the proposed method of practical interest for future engineering applications. (C) 2007 Elsevier B.V. All rights reserved.