On the dynamics of the separation surface in a two liquid layer system

In this paper a theoretical and experimental investigation on the sloshing of two liquid layers with a free-surface is performed. The mathematical model is obtained by applying the Lagrangian variational formulation to the potential formulation of the fluid motion and a dynamical system which describes the dynamics of motion of the separation surface is derived. In order to account the damping of the motion, generalised dissipative forces are considered. To this aim, the logarithmic decrement coefficients are estimated by means of a wavelet analysis performed on the experimental free oscillations of the fluid system. The numerical integration of the mathematical model gives results which are in good agreement with the experimental results.