The coupling and interactions between ship motion and inner-tank sloshing are
investigated by a potential-viscous hybrid method in time domain. For the time domain
simulation of vessel motion, the hydrodynamic coefficients and wave forces are obtained
by a potential-theory-based 3D diffraction/radiation panel program in frequency domain.
Then, the corresponding simulations of motions in time domain are carried out using the
convolution-integral method. The liquid sloshing in a tank is simulated in time domain by
a Navier-Stokes solver. A finite difference method with SURF scheme, assuming a singlevalued
free surface profile, is applied for the direct simulation of liquid sloshing. The
computed sloshing forces and moments are then applied as external excitations to the ship
motion. The calculated ship motion is in turn inputted as the excitation for liquid sloshing,
which is repeated for the ensuing time steps. For comparison, linear inner-fluid motion was
calculated using a 3D panel program and it is coupled with the vessel motion program in
the frequency domain. The developed computer programs are applied to a barge-type
FPSO hull equipped with two partially filled tanks. The time domain simulation results
show reasonably good agreement when compared with MARIN's experimental results.
The frequency domain results qualitatively reproduce the trend of coupling effects but the
peaks are usually over-predicted. It is seen that the coupling effects on roll motions appreciably change with filling level. The most pronounced coupling effects on roll
motions are the shift or split of peak frequencies. The pitch motions are much less
influenced by the inner-fluid motion compared to roll motions.
A developed program is also applied to a more realistic offloading configuration
where a LNG-carrier is moored with a floating terminal in a side-by-side configuration.
First, a hydrodynamic interaction problem between two bodies is solved successfully in
frequency and time domain. A realistic mooring system, including fender, hawser, and
simplified mooring system, is also developed to calculate the nonlinear behavior of two
bodies in time domain simulation. Then, the LNG-carrier and sloshing problem are
coupled in frequency and time domain, similar to the method in the MARIN-FPSO case.
Sloshing effect on LNG-carrier motion is investigated with respect to different tank filling
levels including various conditions such as gap distance between two bodies, selection of
dolphin mooring system, and different cases of environmental conditions using wave, wind,
and current.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85945 |
| Date | 10 October 2008 |
| Creators | Lee, Seung Jae |
| Contributors | Kim, Moo-Hyun |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, born digital |
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