Numerical models of moored floating bodies using meshless method

Four states may appear during a moored floating body's movement (the rope keeps strained, strained first and then slaked, keeps slacked, slacked first and then strained). Based on the moving particle semi-implicit (MPS) method and combined with fluid-structure interaction model, a method to judge the floating body's state is put forward. To simulate the movement of a moored floating body when the rope is strained, a new treatment is introduced. First, calculate the external forces applied by fluid and gravity and their torques using volume integration model and then the estimated value of the velocity and angular velocity of the floating body can be obtained by solving the momentum equation and angular momentum equation. Due to the pulling force applied by the rope in radial direction, the radial component of the estimated velocity is eliminated. The floating body rotates around the fixed end of the rope at a speed equal to the tangential component of the estimated velocity. Utilizing this algorithm, the dynamic response to the movement of a 2-D floating body moored by a single rope in a solitary wave is simulated, and the four states previously mentioned are captured. The trace of the joint point of the rope and floating body during the period when the rope keeps strained is an arc. The data including the movements in the horizontal, vertical and rotation directions can be gained from the calculation. The results agree well with the physical principle. It appears that our finding not only extends the application scope of MPS method, but also provides a new train of thought in simulating the fluid-structure interaction problems of solid bodies whose movement is limited.