Hydrodynamic interaction between ships travelling or stationary in shallow waters

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2014
Thesis identifier
  • T13846
Qualification Level
Qualification Name
Department, School or Faculty
  • This thesis presents the development and application of a numerical method that associates the Rankine source method with double Doppler shift to predict the hydrodynamic interactions between two ships travelling or stationary in shallow waters. Firstly, a 3-D Rankine source panel method was developed to predict the hydrodynamic properties of a single ship travelling with a wide range of forward speeds. Double Doppler shift was taken into consideration in the boundary condition of the control surface. A Wigley III hull travelling with different forward speeds was considered to validate this radiation condition. Comparing with the experimental data, both the hydrodynamic coefficients and motion responses were well predicted by the present method. Then, the method for single ship was extended to ship-to-ship without forward speed problem. Comparing the present calculations of the hydrodynamic coefficients, wave excitation forces and motion responses with the experimental data, as well as with the numerical results from Green function method, a very good agreement was achieved which illustrated that the present program was a useful tool to predict the hydrodynamic behaviours of two ships arranged side by side without forward speed. The effects of mooring and fender system were also discussed based on the linear assumption. Based on the same framework, the 3-D Rankine source panel method associated with double Doppler shift was applied to ship-to-ship interaction with forward speed problem. The validations were established through two pairs of models. The computed dynamic responses of both models in heave and pitch motions showed a good agreement with the published experimental results. However, the prediction of the roll motion was full of challenges due to the inviscid assumption in the potential flow theory. The comparison between the present and Sommerfeld radiation condition was made at τ < 0.25, while the comparison between the present and upstream radiation treatment was made at τ > 0.25. It was shown that the present treatment could obtain a better wave pattern without reflections from the truncated control surface, which confirmed the effectiveness of the present radiation condition as a wave-pattern prediction tool for the ships travelling with a wide range of forward speed. After the validations of the present method, the parametric study about the forward speed and configurations was carried out in order to develop recommendations for ship designers and operators for maximum speed and distance between two ships in given environmental conditions for safe operation. The analytical expression of the semi-wedge angle based on double Doppler shift theory was derived to obtain the wake and quiescent region of the free surface. Based on the semi-wedge angle, the analytical formulation was established to obtain the optimal transvers distance between two travelling ships.
Resource Type
Date Created
  • 2014
Former identifier
  • 1039475