Numerical Seakeeping Predictions Including Interaction Effects between Two Ships
Abstract
A modified version of the SHIPINT program, SHIPINT2, has been developed to compute the restraining forces and motions of the two ship interaction problem in accordance with prescribed captive model test conditions. The coupled motions are computed using a three dimensional panel method with zero forward speed Green's function and a simple forward speed correction. W1th this method, the field points and source points are distributed on the wetted surface of two ships (ship-a and ship-b). The unsteady hydrodynamic forces, wave exciting forces and coupled motion amplitudes are computed based on the two ships interacting. Two ship double-body flow is used to determine the steady flow disturbance potential and velocity distribution. In this computation, them-term computation is performed by the integral equation method based on the double body flow of two ships interacting. Alternatively, with the uniform flow assumption, the approximate m-terms can also be used in this study. Schmitke's method is applied to compute the viscous roll damping coefficients for ship-a and ship-b separately. The viscous interaction between the two ships is neglected. Spectral analyses for irregular waves are also carried out for ship-a and ship-b. Calculations have been carried out in regular waves with heading angles of 120, 150, and180 degrees for two forward speeds of 12 knots and 0 knots. Also cons1dered is a lateral separation distance of 52.705 m, and a longitudinal separation distance djLALsc = 0.25. Ship motions in irregular waves, using the Bretschneider spectrum for Sea State 6 (H5 = 5.0 m, TP= 12.4 s), have also been computed.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2000
- Accession Number
- AD1001546
Entities
People
- C. C. Hsiung
- Liying Li
- Yijun He
Organizations
- Dalhousie University