1. Global Analysis of Floating Structures – M.H. Kim
WINPOST Program
3-D Coupled Analysis
Hull – BEM (3-D panel)
Moorings & Risers – FEM (EI included)
Taut/Catenary Mooring
Top Tensioned, CR, or Flexible Risers
Time & Frequency Domain Models
Simultaneous Solution of Integrated System
Convergence Fast
Single & Multi-Body Problems
GUI Interface

2. Global Analysis of Floating Structures – M.H. Kim
WINPOST Program
Environment
Non-Parallel Waves, Winds, Currents
Uni-direction & Directional Irregular Waves
Dynamic Winds
Up to 3 Currents
Verification & Applications
TLP
Classic & Truss Spar
FPSO

3. Turret – Moored FPSO
Elements (half)
Body: 1843
Free Surface: 480

4. WINPOST vs. MARIN FPSO Model Tests
Percentage Differences based on data in Wichers (2001)
<25 %
25-50 %
> 50 %

5. Multi-Body Interaction OTRC FPSO + Shuttle Tanker (Tandem Moored @ 30m)

6. Global Analysis of Floating Structures – M.H. Kim
WINPOST Program
3-D Coupled Analysis
Hull – BEM (3-D panel)
Moorings & Risers – FEM (EI included)
Taut/Catenary Mooring
Top Tensioned, CR, or Flexible Risers
Time & Frequency Domain Models
Simultaneous Solution of Integrated System
Convergence Fast
Single & Multi-Body Problems
GUI Interface

7. Global Analysis of Floating Structures – M.H. Kim
WINPOST Program
Environment
Non-Parallel Waves, Winds, Currents
Uni-direction & Directional Irregular Waves
Dynamic Winds
Up to 3 Currents
Verification & Applications
TLP
Classic & Truss Spar
FPSO

8. Turret – Moored FPSO
Elements (half)
Body: 1843
Free Surface: 480

9. WINPOST vs. MARIN FPSO Model Tests
Percentage Differences based on data in Wichers (2001)
<25 %
25-50 %
> 50 %

10. Multi-Body Interaction OTRC FPSO + Shuttle Tanker Side-by-Side Moored

11. FPSO Roll Prediction and Mitigation (S.A. Kinnas)
Objective
Develop accurate computationally efficient model to predict the hydrodynamic coefficients in roll for a FPSO hull
Investigate effectiveness of bilge keels (size, shape, location across and extent along the hull) on roll mitigation
Plan
Develop CFD method for unsteady separated flow and added mass and damping coefficients about 2-D hull in roll motions
Use 2-D coefficients (evaluated at different hull stations) to adjust the FPSO roll coefficients predicted by WAMIT
Extend 2-D method to predict the fully 3-D unsteady separated flow and coefficients about the FPSO hull with the bilge keels
Validate with other methods and experiments

12. FPSO Hull Motions: Heave & Roll Coordinate System
Computational Domain
Kinematic BC
Far Boundary
u=v=0
v body • n = q fluid•n
Dynamic BC =0
Hull 
Bilge Keel Details
Description of boundary conditions on a hull moving at the free surface
Grid used for the heave motion
response for a rectangular hull form

13. Oscillating Flow Past a Flat Plate
Grid for Oscillating Flat Plate

14. Oscillating Flow Past a Flat Plate
Axial velocity and streamlines predicted by Euler solver at instant t=0 & T/4 for oscillating flow (-UmCos(ωt)) past a flat plate
u = - Um ←
u = 0 →

15. Oscillating Flow Past a Flat Plate
Comparison between Euler solver, Navier-Stokes solver and experimental data from Sarpkaya, 1995
Euler Navier Stokes Sarpkaya Cd Cm
Euler Navier Stokes Sarpkaya

16. Numerical Results: Heave Motion
Comparison of the added mass and damping coefficients
with Newman(1977) for B/D=2 & No bilge keel

17. Convergence of force histories with increasing grid density
130 30 cells
220 60 cells
B/D = Fr x D = 1.5
310 70 cells

18. Predicted Roll Added Mass & Damping Coefficients for Different Bilge Keels

19. Flow Field Around Hull

20. Status
Developed CFD model to solve the Euler equations around a 2-D hull subject to heave and roll motions
Validated for a flat plate subject to an oscillating flow. Euler results comparable to those from Navier-Stokes and in reasonable agreement to experimental data
Demonstrated that model
Can describe free surface effects by comparisons with potential flow results for a 2-D hull in heave
Results are practically grid independent
Can describe unsteady separated flow around a plate in oscillating flow and around the bilge keel of a 2-D hull subject to roll motions
Can predict expected increase in added mass and damping coefficients with increasing bilge keel size

21. Future Work Develop fully 3-D method
Continue validation of 2-D Hull method with other methods and existing experiments
Develop method to integrate the 2-D Hull results into WAMIT (“2-1/2 D” model)
Use 2-1/2 D to assess effects of various bilge keel designs on motions
Plan & analyze further experiments to validate models
Develop fully 3-D method
assess accuracy of the 2-1/2 D model
Basis for refined analysis of keel designs
Include the effects of the bilge keel “lift”
Basis for more complete models in the future (e.g., non-linear free-surface effects, turbulence)

22. MMS JIP Polyester Rope Goals
Development of a rationale mitigation strategy and guideline for dealing with damaged polyester rope
Installation & In-service damage
Mitigation strategies could include
Installation
Immediate replacement
Periodically monitor for possible replacement later
In-Service
Replace ASAP (continue operations, curtail, or shut-in?)
Support API RP process to develop RP

23. MMS JIP Polyester Rope
Length Effect Tests - potential influence of length effects on tests of damaged ropes (small-scale rope)
Damaged Full-Scale Rope Tests – quantify the influence of damage on full-scale ropes (main focus)
Verification Tests - verify results of Damaged Full-Scale Rope Tests with limited tests on longer full-scale ropes
Four Ropes
Bexco CSL Whitehill Marlow

24. Damaged Rope Test Program

25. Length Effect Tests 2 m sample with midspan damage
23 m sample with damage near splice
35 m sample with midspan damage

26. Simulated Rope Damage Figure 5 Damage Level 1 ~7 in. Diameter Figure 6

27. Residual strength of damaged rope Rope behavior
Results
Residual strength of damaged rope
Rope behavior
Damage level vs. residual rope strength
Residual strength vs. rope/splice construction
Scale effects on residual strength
Effect of length on residual strength
Effect of damage location on residual strength
Data to validate numerical model of damaged rope