2. CDYNAMICS COMPANY INTRO
• Located in Kristiansand, Norway
• Founded in 2015 as a supplier of analysis
services to marine industry
• 5 co-workers
• Expertise in composites and fluid dynamics
• Applicable skills in CFD and FEA to any
engineering problem
http://cdynamics.no/
3. Wavefoil
• Retractable bow foil that dampens heave
and pitch motion
• Decreases fuel consumption in head-on
waves.
Eirik Bøckmann, Phd thesis 2015
wavefoil.com
4. Project objectives
• Structural dimensioning of Wavefoil against
slamming loads
• Find importance of hydroelasticity by
comparing three approaches:
1. Quasi-static: Quasi-static structural analysis
using pressure from rigid structure CFD
2. Dynamic (One-way coupling): Dynamic
structural analysis using pressure from rigid
structure CFD
3. FSI (two-way coupling): Dynamic analysis
where structural deformation affects the
fluid pressure.
5. • Free body drop: Vertical DOF is free.
• Large mass of ship -> nearly constant
velocity impact at 6 m/s
• Flat water surface
• 10 deg deadrise angle
FSI model setup – CFD model
6. Property Value
Software StarCCM+
Timestep 2.5e-5 - 1e-4 s
Cell size at foil 10 mm
Mesh size 500000 cells
Viscous regime Laminar
Co-simulation Implicit
Mesh motion Overset+morphing
Equation of state Compressible (both
air and water)
FSI model setup – CFD model
8. Property Value
Software Abaqus
Element size ~20 mm
No. of elements 23000
Element type Linear quadrilateral
Non-linear geometry No
Timestep 1e-4 s
Boundary condition: vertical
direction is free.
Other DOFs are fixed -> conservative
FSI model setup – FEA model
10. Validation of FSI model
• FSI setup with StarCCM+ and
Abaqus in co-simulation is
validated against drop tests of
cantilever plates by Panciroli et
al. 2012.
Experimental setup from Panciroli et al. 2012
11. Validation of FSI model
• FSI setup with StarCCM+ and
Abaqus in co-simulation is
validated against drop tests of
cantilever plates by Panciroli et
al. 2012.
12. Validation of FSI model
Experimental data from Panciroli et al. 2012
-0.002
-0.0015
-0.001
-0.0005
0
0.0005
0.001
0.0015
0.002
0.0025
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07
Strain[%]
Time[s]
FSI (CFD)
Experiment (Panciroli)
• FSI setup with StarCCM+ and
Abaqus in co-simulation is
validated against drop tests of
cantilever plates by Panciroli et
al. 2012.
13. Results - compressible air effects
• FSI versus quasi-static yields
reduction of bending moment of
50%
• Dynamic vs quasi-static yields
reduction of bending moment of
50%
-0.9
-0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
2.1
0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065
Verticalforce[MN]
Time [s]
Quasi-static Quasi-static (incompressible air)
• Compressible air effects are
relevant
• Part of Hull adjacent to foil
needs to be included in CFD
model
14. • FSI approach renders vertical
force about 40% of quasi-static
• Dynamic approach gives spurious
oscillations because of no
damping
-0.9
-0.7
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
1.5
1.7
1.9
2.1
0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065Verticalforce[MN]
Time [s]
Quasi-static FSI Dynamic
Results – vertical force
15. • FSI bending moment about 40% of
quasi-static
• Dynamic bending moment about
60% of quasi-static
• Incompressible air effects yields
only 10% difference to FSI bending
moment
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.055 0.06 0.065
Bendingmoment[MNm]
Time [s]
Quasi-static FSI (two-way coupling) Dynamic (One-way coupling) FSI (incompressible)
Results – bending moment
22. Conclusions
• FSI and dynamic analysis of Wavefoil yield considerable
reduction in laminate utilization compared to quasi-static
analysis ->
– Lighter structure
– Easier production
• Compressible air effects are only minor in FSI approach
• Dynamic approach can be a good trade-off between CPU
time/cost and accuracy
23. THANK YOU FOR YOUR TIME
MARINE || COMPOSITES || RENEWABLES || SUBSEA
post@cdynamics.Contact
