CFD, system-based and EFD study of ship dynamic instability events: Surf-riding, periodic motion, and broaching

Multidisciplinary experiment using steep regular waves to determine ship operating conditions that avoid capsize

“…In these particular trajectories, the continuous periodic yawing of the model is clearly visible. The trajectory plots of Sadat-Hosseini et al (2011) show this same type of motion as well. Two runs were completed for each test condition, resulting in six total trajectories displayed in the figure.…”

“…Hamamoto et al (1996) did extensive model tests looking at capsize and classified conditions under which harmonic resonance, parametric resonance, and pure loss of stability lead to ship capsize. Sadat-Hosseini et al (2011) undertook a coupled experimental and numeric investigation of surf-riding, periodic motion, and broaching in which they numerically simulated these dynamic stability events using regular waves. Using a slightly different approach, Cotton and Spyrou (2001) explored understanding capsize as functions of wave frequency and height for a yaw restricted 2D model.…”

“…For instance, Pérez-Rojas et al (2007) found that they could not maintain their desired course with an automatic controller and had to manually steer, although the type of control algorithm used is not mentioned. Using only a proportional controller, Sadat-Hosseini et al (2011) occasionally struggled to achieve the desired relative wave heading and consequently had a steady-state heading error. This situation presents a potential problem because if a controller needs to be fine tuned for each particular operating condition and wave environment of interest, then the time advantage of testing in steep regular waves is lost to time spent repeatedly adjusting the control algorithm.…”

Analysis of propeller bearing loads by CFD. Part I: Straight ahead and steady turning maneuvers

“…In fact, in order to capture the characteristic spatial and time scales of the flow around the propeller blades, the typical time step should be at least two orders of magnitude lower than the one typically adopted for the same simulation with the effect of the propeller modeled by, e.g., an actuator disk model; in addition, the mesh size close to the propeller and in the near wake may be properly refined. A very limited number of this kind of simulation is documented in the open literature, both for the straight ahead condition as well as in free motion in waves or maneuvering (Muscari et al, 2011;Castro et al, 2011;Mofidi and Carrica, 2014;Carrica et al, 2012;Sadat-Hosseini et al, 2011). Moreover, it has to be stressed that, although the propeller loads (hub or blade loads) were computed, the validation process was not complete, because only thrust and torque (when available) were measured during model tests.…”

Broaching probability for a ship in irregular stern-quartering waves: theoretical prediction and experimental validation

“…The measured rudder normal forces agreed reasonably well with numerical simulation, and the effect of rudder emergence significantly improved prediction accuracy for broaching. Note here that Sadat-Hosseini et al [34] applied computational fluid dynamics (CFD) to the broaching of a twin-propeller and twin-rudder ship in regular waves, and compared the results with a free-running model experiment. Since this approach requires tremendous computational resources even for regular waves, its direct application to regulations is impractical, so system identification techniques were applied to the CFD results to improve the 6 DOF mathematical model [35].…”