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

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

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

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

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

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

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

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

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

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

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

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

Oscillating Flow Past a Flat Plate Grid for Oscillating Flat Plate

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 →

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

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

Convergence of force histories with increasing grid density 130 30 cells 220 60 cells B/D = 2 Fr x D = 1.5 310 70 cells

Predicted Roll Added Mass & Damping Coefficients for Different Bilge Keels

Flow Field Around Hull

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

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)

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

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

Damaged Rope Test Program

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

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

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