The 12th International Conference on Hydrodynamics
18 – 23 september 2016, Egmond aan Zee, The Netherlands
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COUPLED TIME DOMAIN METHOD FOR SHIP DYNAMICS AND SLOSHING FLOWS


Go-down ichd2016 Tracking Number 67

Presentation:
Session: Ship hydromechanics resistance IV
Room: Room 1
Session start: 10:30 Tue 20 Sep 2016

José Miguel Fonfach   jose.fonfach@live.com
Affifliation: Universidade Federal do Rio de Janeiro

Marcelo Neves   masn@laboceano.coppe.ufrj.br
Affifliation: Universidade Federal do Rio de Janeiro


Topics: - Ship hydrodynamics resistance, propulsion, powering, seakeeping, manoeuvrability, slamming, sloshing, impact, green water

Abstract:

In the present contribution, a numerical study of the coupling effect between the sloshing flows and ship sway motion under beam regular waves is carried out employing a coupled time domain method. The lateral ship dynamics is solved using an “Instantaneous Update” algorithm. Sequentially, sloshing Y-forces are obtained by the I-MPS (Improved Moving Particle Semi-Implicit) method. The “Instantaneous Update” algorithm is a 6DOF (six degrees of freedom) seakeeping simulator, where a frequency-domain calculation of the radiation and diffraction coefficients is required as input data, which is performed by a panel method. Furthermore, non-linear effects are incorporated to calculate the instantaneous position of the ship, and the external wave excitation forces are calculated at each time step, considering the relative positon between the excitation waves and ship surfaces. The sloshing flow solver is a 2D (two dimension) robust method based on particle interactions in a Lagrangian coordinate system. Sloshing simulations are performed within a closed domain in which the free surface is modelled as a deformable surface for a single-phase flow. For the coupled process, the sloshing-induced forces are included into the external wave-excitation forces, and then the corresponding position of the ship is actualized. At the same time, the sloshing flow is consequence of the instantaneous ship motion. In order to assess the numerical method, the coupled time domain method is validated for the sway motion of a barge with two identical rectangular tanks with length 25% of the barge length, according with Rognebakke & Faltinsen (2001) experiments. The study takes into account one or two tank filled and several amounts of water in the tank for a range of excitation wave frequencies near to the eigenfrequency of the fluid motion in the tanks. REFERENCES [1] Rognebakke, O. R. and Faltinsen, O. M., (2001), “Effect of sloshing on ship motions”, 16th International Workshop on Water Waves and Floating Bodies, Hiroshima, Japan