## F. Static Analysis of a Hydroelastic System (STA5)

In this analysis, the structure and fluid interact all along their interface. The pressure must be declared uniform in the fluid domain (orin each distinct fluid domain if several exist). The fluid surfaces that arenot in contact with the structure must then support a zero pressure or zeroflux pressure condition, as in the case of a tank. The system of equations (1)can be rewritten to be symmetric:

The user must provide the loading data F, -q, -fb using the LOADS entry and/or the prescribed displacements U,electric potentials F, currents I, pressures P ongiven nodes using the EXCITATIONS entry. The codecomputes the displacement and pressure fields over the entire structure. F, -q and -fb must be accurately defined for thefinite-element model. This means that they must be divided by 2p if the model is axisymmetrical, by 2 if the mesh islimited by a symmetry plane, etc. The user must define a mesh and the boundaryconditions, eliminating the rigid body modes associated with the singularity ofthe system of equations. Only one loading case can be solved at a time. Taking internal losses into account does not make physical sense in thisanalysis and thus is not possible.

The applied forces must be concentrated at the nodes (see LOADS entry). Displacements are prescribed using the EXCITATIONS entry. The matrices are assembled and stored tofile by columns. Gaussian algorithms are used to solve the problem, in singleor double precision.