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

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Fluid-Structure Interaction (FSI) • Analyze VIV using Computational FSI with

Abaqus and STAR-CCM+

Pressures

Displacements

FSI

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Assumptions • single mode response

(1st mode)

• uniform current flow

• an empty pipeline

• zero axial tension

Assumptions

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• 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

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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

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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

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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

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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

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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

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Box-Behnken Design

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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.

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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.

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Questions?