# The Effect of Porous Media on Wave-Induced Sloshing in a Floating Tank  
[PERSON]  
1 Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803, USA;  
sloshing analysis. They found that numerical computations for liquid impacts are very unpredictable. [PERSON] et al. [2] used an efficient hybrid method that involves the impulse response function (IRF) for ship motions and a Reynold-averaged Navier-Stokes (RANS) solver for sloshing to simulate the sway motion of a barge with rectangular tanks and the roll motion of a hull with an anti-rolling tank (ART). [PERSON] et al. [3] employed a similar approach for a floating production system equipped with two liquid tanks. They found that the coupling effect shifts the motion frequencies and induces the nonlinear motion amplitudes. [PERSON] et al. [4] compared the potential-flow and Navier-Stokes models. They concluded that the sloshing fluid can significantly influence the ship's surge and roll motions but hardly affects the heave motion. Their results showed that potential-based numerical methods are very suitable for most scenarios of sloshing in tanks on ships. To mitigate vibration, a common solution is to deploy bilge kels on the hull to increase the hydrodynamic resistance and damping from the vortex [5]. An ART, which consists of two vertical ducts connected at the bottom with a horizontal duct, distributed along the centerline of the ship, is another effective damper for rolling reduction. Such a liquid damper is also called a tuned liquid column damper (TLCD) in structural engineering. Their active control is enabled by installing propellers or pumps in the middle of the bottom tank [6; 7; 8]. For other floating structures, such as compliant towers, tension leg platforms, and floating production systems, the tuned mass damper (TMD), which is an auxiliary mass attached to the main structure through springs and dashpot elements, is a common vibration absorber [9; 10]. It generates an out-of-phase control force against the external excitations and dissipates the kinetic energy of the main structure. Its performance can be maximized as the tuning condition is satisfied, i.e., the frequencies of the damper and structure are close. TMD systems have been widely applied to offshore wind turbines to handle some complicated phenomena such as gyroscopic effects, wind turbulence and shear, tower shadow, and the wake effect from neighboring turbines [11; 12; 13]. In the ocean environment, a tuned liquid damper (TLD), which is a water tank that dampens structural vibrations by the fluid viscosity, can be more suitable because of its convenience, economy, and simplicity [14; 15]. However, its inherent viscosity is too small to provide sufficient damping and the accompanying nonlinear sloshing behavior can easily lead to mistuning [16]. The work of other researchers has sought to enhance the damping effect by placing internal obstructions such as baffles [17] and screens [18] inside the tank. Induced characteristic changes have been successively analyzed [19; 20; 21], but progress toward a practical application remains stagnant because it is difficult to satisfy the tuning condition and optimal damping at the same time. Another new type of TLD with porous media was proposed to seek optimal performance through a mechanical model [22; 23]. [PERSON] and [PERSON] [24] carried out free decay experiments to verify the linear dynamic characteristics. [PERSON] et al. [25] calculated the nonlinear damping ratio using resonance experiments. [PERSON] and [PERSON] [26] considered the Forchheimer flow in the numerical model and derived two essential parameters that appear in the mathematical model. However, the previous research studies only focused on the characteristics of the TLD systems instead of their application in FSI problems.