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Coupling of Cable FEA Solution With 6 DOF CFD Solution for Subsea Equipment Launching Simulation
Fabio Saltara Roberto Monteiro Basto da Silva Ricardo Barbosa Damian Ismael Lis Alves Daoud Armando Alvarez de Souza Regis Ataides
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Problem Description
Subsea Equipment Launching Simulation
Alternatives:
- AQWA-FLUENT coupling
- Structural ANSYS – FLUENT coupling
- FLUENT User Defined Function (UDF) Solution
Problem Description
Methodology – FEA Solution
cablesdragbuoyancyweightmassaddedinertia FFFFFF
cablesdragdAA
a FFgmmt
tdttdmm
2
ma = added mass
md = displaced fluid mass
Methodology – FEA Solution (2D Formulation)
yneighbour
xneighbour
yA
xA
o
d
d
d
d
mlmmlm
lmllml
L
EAdK
22
22
L
xxl
L
yym
AneighbourAneighbour
L
txtx
L
LLEAFgmmttdK
t
tdttdmm
Aneighbour
cables o
odragd
cables
AAa
)()(
2
Where:
Methodology – 6DOF and FEA Coupling
connectors
bodyichydrodynamext TgmFF
connectors
ichydrodynamext TrMM
,,,6
CGCGDOF
xx
trxd CGconnectors
Case 1
Case 1
26,022 cells
11,622 triangular cells
14,400 quadrilateral cells
t=0.01 s
Spalart-Allmaras Turbulence
Model
Final Time: 118 s
Boundary Conditions
Deforming + Remeshing Methodology
- After five time-steps the triangular cells are remeshed;
- At each time-steps the mesh is deformed according to a displacement diffusion methodology:
.boundarynearestthetodistancetheisawhere,1
;velocitymeshtheiswhere
0
2a
W
x
W
x
i
j
i
j
Results - Case 1
Results - Case 1
Case 2
Final time around 265 s. Mesh and other settings are the same of Case 1.
Results - Case 2
Results - Case 2
Conclusion
It was demonstrated that it is possible to use a FLUENT User Defined Function (UDF) for the FEA solution of the cable forces and displacements during the simulation of the pendulum motion that is a feature of the launching of subsea equipment and it is feasible to run a full CFD simulation of this type of operation.
Next Steps
• Development of the full 3D methodology ( involves only changing the [K] matrix );
• Evaluation of other turbulence models;
• Evaluation of other moving mesh methodology (could all mesh be considered as having rigid body motion?);
• Parallelization of the UDF;
• Mesh generation for a 3D case.