Experimental measurement of the surface velocity field in an externally induced sloshing tank

In this work, the unsteady free-surface velocities during the surge motion of a liquid tank are determined through experimental investigation. A new experimental approach has been discussed for capturing the free surface of the liquid during tank excitation. In order to avoid violent motion in the tank, the tank is excited with a low frequency (up to 47 per cent of the first-mode frequency) which leads to low-steepness waves in the container. When a container oscillates at a low excitation frequency, the wave amplitude A is usually small. Since the wave steepness E is directly proportional to the wave amplitude, the wave steepness is also small during the motion. The planar two-dimensional particle image velocimetry technique is used to calculate the U and V velocities of the free surface, while the interface location technique is used to determine the vertical velocity W of the interface. The velocities are measured for various liquid fill levels and excitation frequencies. The average line velocity V w near the tank wall and the average line velocity V c near the velocity tank centre with respect to time are estimated and compared with the tank velocity. The observed flow patterns indicate the presence of complicated flows during the sloshing experiment.