An improved fluid superelement for the coupled solid‐fluid‐surface wave dynamic interaction problem

The dynamic solid-fluid-surface wave interaction problem can be solved with known Finite Element solutions. However, these solutions are complicated by the unsymmetric nature of the matrix equation to be solved. This paper shows how the numerical problem can be simplified by symmetrization, without loss of physical generality, using specialized Lagrange co-ordinates for the fluid free surface wave, and by introducing a Lagrange multiplier representing a generalized fluid pressure. With these improvements, solid-fluid-surface wave analysis capabilities can easily be added to most Finite Element structural analysis programs. Numerical examples of the performance of the improved formulation are given for earthquake analysis.