CFD Simulation and Experimental Study on Coupled Motion Response of Ship with Tank in Beam Waves

Tank sloshing is widely present in many engineering fields, especially in the field of marine. Due to the trend of large-scale liquid cargo ships, it is of great significance to study the coupled motion response of ships with tanks in beam waves. In this study, the CFD (Computational Fluid Dynamics) method and experiments are used to study the response of a ship with/without a tank in beam waves. All the computations are performed by an in-house CFD solver, which is used to solve RANS (Reynold Average Navier-Stokes) equations coupled with six degrees-of-freedom solid-body motion equations. The Level Set Method is used to solve the free surface. Verification work on the grid number and time step size has been conducted. The simulation results agree with the experimental results well, which shows that the numerical method is accurate enough. In this paper, several different working conditions are set up, and the effects of the liquid height in the tank, the size of the tank and the wavelength ratio of the incident wave on the ship’s motion are studied. The results show the effect of tank sloshing on the ship’s motion in different working conditions.

Direct CFD Simulation and Experimental Study on Coupled Motion Characteristics of Ship and Tank Sloshing in Waves

It is of great significance to study the tank sloshing, especially the coupling motion between tank sloshing and ship in waves with strong non-linearity and randomness. In this study, the response of the ship with/without tank in regular wave is studied by EFD method and CFD method. All the simulations are carried out by in-house CFD code HUST-Ship (hydrodynamic unsteady simulation technology of ship) to solve RANS equations coupled with six degrees of freedom solid body motion equations. RANS equations are solved by finite difference method and PISO algorithm. A two-equation Shear Stress Transport (SST) k-w turbulence model is used. The simulation results are in good agreement with the experimental results, which also indicates that the result of the tank sloshing simulated by in-house CFD code is reliable. The influence of sloshing on ship motions is estimated by comparing the experimental results between the ship with/without tank in different wave conditions. The coupling motion characteristics between the liquid in the tank and the ship is further studied by the CFD method. The study shows that the influence of tank sloshing on ship motion is different under the action of different regular waves.

The influence of obliquely perforated dual-baffles on sway induced tank sloshing dynamics

This paper examines the influence of oblique perforated baffles on the sloshing dynamics of rectangular liquid storage tanks. The analysis presented accounts for sway induced hydrodynamic forces and entropy generation. Internal liquid free surface oscillation is modelled by the volume of fluid method. The effect of baffle geometric parameters, orientation and porosity on loads is examined and numerical results are compared against a set of experiments. Consequently, an engineering method suggesting the optimum size, angle of inclination and topology of baffles for the case of a rectangular tank is presented. It is shown that implementation of optimized oblique porous dual baffles may reduce sloshing loads by up to 15%.

Analytical Study on the Effect of a Horizontal Perforated Plate on Sloshing Motion in a Rectangular Tank

Tank sloshing in a liquid cargo ship will cause instability or even overturning of its carrier if the external wave frequency is close to the natural frequency of the tank. The inherent damping of a tank without inner structures has been found to be insufficient for suppressing violent sloshing motion. A variety of damping plates have been designed to increase the inherent damping of the tank. Of them, a horizontal perforated plate (HPP) has been proved to be effective for dissipating energy in a swaying tank through experiments. In this study, the sloshing problem in a tank with an HPP under swaying and rolling excitation is analytically studied based on the potential theory. The quadratic pressure loss boundary at the perforated plate is adopted, and the matched eigenfunction expansion method (MEEM) with iterative calculations is used to develop the analytical model. Based on the different porosities and submerged depths of the plate, both the free surface elevations and the hydrodynamic coefficients are carefully examined. The results give a better understanding in the effect of the inner HPP on the sloshing motion in the ship tank.

Computational Simulation of Fuel Tank Sloshing for a FSAE car using CFD Techniques

Sloshing refers to the highly random motion of any fluid inside an object where the dynamic forces of the liquid can interact with the object to alter the overall system dynamics. This work summarises the process of designing and simulating the 3-D geometry of a fuel tank using CFD and the volume of fluid (VOF) method considering multi-phase fluid flow predicting fuel slosh movement at a specific capacity within a definite fixed volume.[13-16] As the performance of the engine heavily depends on a constant supply of fuel, the splashing of gasoline inside the partially filled fuel tank can severely affect the performance when subjected to sudden left and right turns during a Slalom in FSAE tracks. This scenario can be modelled, analysed and effectively controlled by reducing pressure intensities inside the tank walls using a set of strategically placed Baffles. Therefore, this study attempts to reduce the sloshing behaviour by considering multiple types of geometries and shows the final geometry chosen using computational simulations inside the fuel tank considering 1.5 litres of fuel and remaining with air inside a 7.3 litres fuel tank, thus predicting the effect of sloshing forces and moments inside the tank structure considering lateral and longitudinal acceleration fields. The model is discussed and results are presented. In addition, this paper can be referred to as a detailed tutorial on how to simulate and take in consideration of all the factors which will be useful in deciding vehicle fuel requirements and optimum design.

Experimental Validation of Single- and Two-Phase Smoothed Particle Hydrodynamics on Sloshing in a Prismatic Tank

This study aimed to validate the single-phase and two-phase smoothed particle hydrodynamics (SPH) on sloshing in a tank. There have been many studies on sloshing in tanks based on meshless particle methods, but few researchers have used a large number of particles because there is a limitation on the total number of particles when using only CPUs. Additionally, few studies have investigated the influence of air phase on tank sloshing based on two-phase SPH. In this study, a dedicated sloshing experiment was conducted at the National Research Institute of Fishing Engineering using a prismatic tank with a four-degrees-of-freedom forced oscillation machine. Three pressure gauges were used to measure local pressure near the corners of the tank. The sloshing experiment was repeated for two different filling ratios, amplitudes, and frequencies of external oscillation. Next, a GPU-accelerated three-dimensional SPH simulation of sloshing was performed using the same conditions as the experiment with a large number of particles. Lastly, two-dimensional sloshing simulations based on single-phase and two-phase SPH were carried out to determine the importance of the air phase in terms of tank sloshing. Based on systematic comparisons of the single-phase SPH, two-phase SPH, and experimental results, this paper presents a detailed discussion of the role of air-phase in terms of sloshing. The currently achievable accuracy when using SPH is demonstrated together with a few sensitivity analyses of SPH parameters.