Nonlinear finite element analysis of water in rectangular tank

The present paper deals with the nonlinear finite element analysis of water in rectangular tank. Pressure is considered as independent nodal variables in the governing equations and the nonlinear convective acceleration in Navier-Stokes equations is incorporated in the analysis and the tank walls are considered as rigid. Water domain is discretized and modeled by eight node isoparametric elements. The nonlinearity effects of the fluid are studied due to harmonic of various frequencies and amplitudes and random excitation. Linear and nonlinear hydrodynamic pressures on tank wall are compared to evaluate the efficiency of the present model. The results show that the convective nonlinearity enhances the magnitude of hydrodynamic pressure to a considerable amount when the excitation frequency is equal to or lower than the fundamental frequency of the water within the tank and the increase becomes quite larger for comparatively narrow tank. However, the increase in pressure is insignificant when the vibrating frequency is higher than the frequency of the fluid domain. The distribution of nonlinear hydrodynamic pressures is almost similar to that of linear pressures due to seismic excitation.