Experiments and computational fluid dynamics (CFD) are used to study the effect of slat screens with three different solidity ratios Sn (the ratio between solid area and total area of the screen under the mean free surface) on sloshing in a two-dimensional tank in finite water depth (h/l = 0.4, with h and l the water depth and length of the tank, respectively). The steady-state responses of the waves and horizontal forces are analyzed. The effect of the solidity ratio on the natural/resonant frequency of sloshing is addressed. In addition, the effect of initial conditions on the steady-state results is also depicted.
Swash bulkheads and baffles are used to diminish sloshing in the cargo and fuel tanks of ships. Faltinsen and Timokha (2009) give a thorough investigation of the effectiveness of these devices using theoretical/empirical methods. Large solidity ratio slat screens similar to swash bulkheads alter the resonant sloshing frequencies, shifting them to higher values (slat screens used in this study are made of a limited number of horizontal slats). This is of interest if the new higher sloshing frequencies are away from the energetic frequency range of the typical sea states, which in fact reduces the risk of occurrence of large pressures due to sloshing. This effect has been investigated for finite water depth using experiments and linear and nonlinear modal methods where the effect of the screen was introduced into the modal equations as a quadratic pressure loss term (Faltinsen et al., 2011a; Faltinsen et al., 2011b; Faltinsen et al., 2011c). In shallow water, Love and Tait (2010) modified the multimodal method of Faltinsen and Timokha (2001) to include damping terms that account for the screen in a tuned liquid damper (TLD). The latter work and similar works on TLDs consider small solidity ratios Sn (typically smaller than 0.5). This means that the lowest natural frequency does not experience a substantial change (essential for a TLD) and the screen acts more like a damping device. In marine applications, however, it is of interest to consider large solidity ratios to modify the natural/resonant sloshing frequencies.
