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Determining What Vortex-Induced Vibration Variables have the Maximum Effect on a Pipeline
Free Span’s Amplitude of Displacement with Computational Fluid-Structure Interaction
ASME V&V 2013-2315
Authors: • Marcus Gamino • Samuel Abankwa • Ricardo Silva • Edwin Johnson • Michael Fisher
• Raresh Pascali • Egidio Marotta, • Carlos Silva • Alberto Rivas
ASME V&V 2013
Outline – Objective – Background (Free spans and VIV) – Fluid-Structure Interaction (FSI) – Assumptions – Procedure – Mesh Sensitivity Studies (Grid Independence) – Space-Filling Design – Full Factorial Design – Box-Behnken Design – Conclusions – Questions
Outline
ASME V&V 2013
Objective
• To determine the effects of different Reynolds number, Re, variables (i.e. flow velocities, change in pipe diameter, and fluid densities) on the maximum amplitude of displacement of a pipeline free span due to vortex-induced vibration (VIV).
Objective
ASME V&V 2013
Free Span • A free span is a section of
subsea pipeline that is not supported by the seabed.
• Caused by: – Seabed unevenness – Change in seabed topology
caused by the environment
• Susceptible to fatigue damage from vortex induced vibration
www.formshore.com
Background
http://www.neo.no/research/pipeline/xplisit.html
ASME V&V 2013
Vortex-Induced Vibration • Alternate vortices develop
behind the structure as the underwater current moves past the pipe
• This alternate vortex shedding results in structural vibrations of subsea piping components including free spans and jumpers
• Maximum amplitude of displacement occurs when the structure’s natural frequency is the same as the vortex shedding frequency behind the structure
Background
ASME V&V 2013
• This vibration is a major source of concern in fatigue assessment of free spans, risers, and jumpers
• Maximum amplitude of displacement occurs when the structure’s natural frequency is the same as the vortex shedding frequency behind the structure
M-Shape Jumper
Background
ASME V&V 2013
Fluid-Structure Interaction (FSI) • Analyze VIV using Computational FSI with
Abaqus and STAR-CCM+
Pressures
Displacements
FSI
ASME V&V 2013
Assumptions • single mode response
(1st mode)
• uniform current flow
• an empty pipeline
• zero axial tension
Assumptions
ASME V&V 2013
• In Abaqus three pipeline free spans with different diameter and thickness were modeled
• Material: Steel
• Young’s Modulus: 30x10^6 psi
• Poison’s Ratio: 0.3
Outside Diameter
(in.)
Thickness (in.)
Inside Diameter
(in.) Min 8 0.8 6.4
Max 12 1.2 9.6
Procedure
ASME V&V 2013
• Mesh pipeline with C3D8R elements (8-node linear brick elements)
• Edges of pipeline were divided by 12 seeds
• Number of nodes and elements in the model equal 16,560 and 8,256 respectively
Procedure
ASME V&V 2013
• Dynamic implicit analysis
• Used a fixed (encastre) boundary conditions for the free span.
• Create an input file to import to STAR-CCM+
• Mesh the free span and environment
• Setup physics with RANS (Reynolds average navier stokes equations)
• Run Co-simulation
Procedure
ASME V&V 2013
• Determine best mesh based on computational time and accuracy
• Used midpoint (m) values for sensitivity analysis
– Diameter = 10 in
– Velocity = 1.25m/s
– Density = 846.848 kg/m3
ρ
velocity Diameter
m
Grid Independence
ASME V&V 2013
Run Number of
Cells
Base Size
(inches) Max Displacement (inches) Run Time
1 37051 10 2.888x10-2 approx. 1 hour
2 46029 9 2.702x10-2 approx. 1 hour
3 88378 7 2.615x10-2 approx. 1 hour and 20 min
4 242265 6 2.613x10-2 approx. 2 hours and 10 min
Grid Independence
ASME V&V 2013
Space Filling Design
Velocity Range: 0.5 – 2 m/s
Pipe Diameter Range: 8 – 12 inches (0.2 – 0.3 meters)
Fluid Density Range: 696.135 – 997.561 kg/m^3
Inputs:
ASME V&V 2013
Run Pipe Diameter (in.)
Fluid Velocity (m/s)
Density (kg/m^3)
Displacement (in.)
1 12 1.1 937.2758 1.978x10-2
2 8 0.8 876.9906 2.215x10-2
3 11.2 2 816.7054 3.851x10-2
4 10.4 0.5 756.4202 0.7909x10-2
5 8.8 1.4 696.135 3.326x10-2
6 9.6 1.7 997.561 4.816x10-2
Space Filling Design
ASME V&V 2013
Space Filling Design
• Fluid Velocity has the greatest effect on the amplitude of the free span’s displacement
• Change in density has the least effect
ASME V&V 2013
Do (in) v (m/s) ρ (kg/m3)
1 8 0.5 696.135
2 8 0.5 997.561
3 8 2 696.135
4 8 2 997.561
5 12 0.5 696.135
6 12 0.5 997.561
7 12 2 696.135
8 12 2 997.561
12 in
8 in
0.5 m/s
2 m/s
696.135 kg/m3
997.561 kg/m3
Full Factorial Design
ASME V&V 2013
Displacement Values Interactions
Do (in)
v (m/s)
ρ (kg/m3)
X (x10-2 in)
1 8 0.5 696.135 2.215
2 8 0.5 997.561 1.334
3 8 2 696.135 7.238
4 8 2 997.561 10.36
5 12 0.5 696.135 0.6279
6 12 0.5 997.561 0.8991
7 12 2 696.135 2.943
8 12 2 997.561 4.208
Full Factorial Design
ASME V&V 2013
Box-Behnken Design
Run Pattern
Pipe Diameter
(in.)
Fluid Velocity
(m/s)
Density (kg/m^3)
Displacement (in.)
1 --0 8 0.5 846.848 1.133x10-2
2 -+0 8 2 846.848 8.801x10-2
3 +-0 12 0.5 846.848 0.7626x10-2
4 ++0 12 2 846.848 3.573x10-2
5 0-- 10 0.5 696.135 0.7458x10-2
6 0-+ 10 0.5 997.561 1.066x10-2
7 0+- 10 2 696.135 4.855x10-2
8 0++ 10 2 997.561 6.951x10-2
9 -0- 8 1.25 696.135 3.412x10-2
10 +0- 12 1.25 696.135 1.699x10-2
11 -0+ 8 1.25 997.561 4.888x10-2
12 +0+ 12 1.25 997.561 2.429x10-2
13 000
(midpoint) 10 1.25 846.848 2.615x10-2
itl.nist.gov
ASME V&V 2013
Box-Behnken Design
ASME V&V 2013
Conclusions • Fluid Velocity has the greatest effect on free span
displacement when subjected to VIV
• Compared to velocity and pipe diameter, the change in density has very little affect on the displacement of the free span
• The Box-Behnkin Surface Response Design is the optimal design for this experiment, for it seems the response variations along the input ranges are nonlinear.
Conclusions
ASME V&V 2013
Future Work • Use FSI methodology and
other advanced computational analysis to verify assumptions made in design codes.
• Fatigue life analysis based on ASTM standards (e.g. ASTM E1049) may be performed in combination with the Palmgren-Miner rule to estimate the fatigue life.
ASME V&V 2013
References • Abaqus Version 6.7 Extended Functionality Documentations, 2007. • Blevins, R.D. Formulas for Natural Frequency and Mode Shape. New York: Van Nostrand
Reinhold, 1979. • Chica, L., Pascali, R., Jukes, P., Ozturk, B., Gamino, M., and Smith, K. Detailed FSI Analysis
Methodology for Subsea Piping Components. Proceedings of the ASME 31st International Conference on Offshore Mechanics and Artic Engineering. (2012): 1-11.
• DNV (2006), “Free Spanning Pipeline,” DNV-RP-F105. • Lienhard, John H. Synopsis of Lift, Drag, and Vortex Frequency Data for Rigid Circular
Cylinders. Pullman, WA: Technical Extension Service, Washington State University, 1966. • Palmer, Andrew Clennel, and Roger A. King. Subsea Pipeline Engineering. Tulsa, Okla:
PennWell, 2008. • Recommended practice DNV-RP-F105. (2002). Free Spanning Pipelines. Hovik, Norway:
Det Norske Veritas. • “Standard Practices for Cycle Counting in Fatigue Analysis.” ASTM E1049 - 85(2011)e1. • Star CCM+ Training. “Lectures CCM+.” CD-Adapco offices. Houston, TX 15 Jul. 2011.
ASME V&V 2013
Questions?