Boundary Element Method for Fluid-Structure Interaction Problems in Liquid Storage Tanks

Abstract

The dynamic response of liquid storage tank, including the hydrodynamic interactions, subjected to earthquake excitations is studied by the combinations of boundary element method and finite element procedure in this paper. The tank wall and inviscid fluid domain are treated as two substructures of the total system-coupled through the hydrodynamic pressures. The boundary element method is employed to determine the hydrodynamic pressures associated with small amplitude excitations and negligible surface wave effects in fluid domain which are expressed as the frequency-dependent terms related with the natural vibration modes of elastic tank alone. These terms are incorporated into the finite element formulation of elastic tank in frequency domain and the generalized displacements are computed by synthesizing their complex frequency response using Fast-Fourier Transform procedure. Thus, the hydrodynamic interactions between the elastic flexible tank wall and the fluid are then solved. To demonstrate the accuracy and validity of the solution procedure developed herein, numerical examples are analyzed. Good correlations between the computed results with the referenced solutions in literature can be noted. The effects of fluid compressibility and tank flexibility are also evaluated in this work. Finally, the dynamic response of liquid storage tank due to seismic excitations is also analyzed.