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Monopile with Dissolving Sacrificial Anodes
Introduction
A monopile foundation is a large-diameter structural element that can be used to support, for instance, an off-shore windmill.
This application exemplifies how the cathodic protection of a monopile decreases over time as the sacrificial anodes dissolve. The example includes secondary current distribution electrode kinetics on the protected steel structure, defining simultaneous metal dissolution and oxygen reduction (mixed potential).
By including a lumped resistance in the model between the upper structure and the lower steel pipe foundation, it is seen that the corrosion protection of the lower part is worsened.
Model Definition
The monopile geometry consists of an upper part (“the transition piece”) with a coated steel surface, and a lower uncoated steel pipe. Both parts are based on slightly conical cylinders, and the upper part also features a smaller ladder and a platform. Around the monopile arrays of sacrificial anodes are placed. The surrounding ocean (salt water) and sea bed (mud) are defined as cylinders. Symmetry is used to half the problem size. The geometry is shown in Figure 1.
Figure 1: Model geometry.
The monopile steel surface is defined using Electrode Surfaces nodes, including simultaneous oxygen reduction and steel oxidation. Tafel kinetics is used for defining the steel oxidation reaction, and different kinetic parameters are used for the coated transition piece and the uncoated lower pipe. The oxygen reduction kinetics is defined using a limiting current density, which has a lower value on the mud-covered surface.
The sacrificial anodes are drawn as edges in the geometry and modeled using Sacrificial Edge Anode nodes. As the anodes are dissolved the radius of the anodes are lowered, and when the terminal radius is reached the anodes are shut off.
The model is solved using a Time-dependent study for a time period of twelve years. Two cases are investigated. In the first case the whole monopile is grounded. In the second case the transition piece is grounded and the lower pipe is assumed to be connected to the transition piece through a lumped resistance.
Results and Discussion
Figure 2 shows the steel surface potential at the beginning of the simulation. A higher potential indicates a more oxidative (corrosive) environment. The mud-covered part of the monopile is exposed to the highest potentials.
Figure 2: Steel surface potential at the beginning of the simulation.
Figure 3 and the close-up in Figure 4 depicts the potential at the end of the simulation. Compared to the situation at t = 0, the potentials are generally higher, especially for the lower part. Figure 4 also shows that the anodes facing the lower part of the monopile have been consumed at a higher rate.
Figure 3: Steel surface potential at the end of the simulation.
Figure 4: Steel surface potential at the end of the simulation (close-up).
Figure 5 and Figure 6 show the steel oxidation current density, that is the corrosion rate, at the beginning and end of the simulation, respectively. The corrosion rate increases approximately three orders of magnitudes as a result of the dissolution of the anodes.
Figure 5: Steel oxidation current density at the beginning of the simulation.
Figure 6: Steel oxidation current density at the end of the simulation.
Figure 7: Steel oxidation current density at the end of the simulation when introducing a lumped resistance between the transition piece and the lower part of the monopile.
Figure 7 shows the steel oxidation current densities at the end of the simulation for the second case when a lumped resistance between the lower and upper part of the monopile has been introduced. The corrosion rate for the lower part is generally higher compared to Figure 6.
Application Library path: Corrosion_Module/Cathodic_Protection/monopile
Modeling Instructions
From the File menu, choose New.
New
In the New window, click  Model Wizard.
Model Wizard
1
In the Model Wizard window, click  3D.
2
In the Select Physics tree, select Electrochemistry>Cathodic Protection (cp).
3
Click Add.
4
Click  Study.
5
In the Select Study tree, select General Studies>Time Dependent.
6
Click  Done.
Global Definitions
Parameters 1
1
In the Model Builder window, under Global Definitions click Parameters 1.
2
In the Settings window for Parameters, locate the Parameters section.
3
Click  Load from File.
4
Browse to the model’s Application Libraries folder and double-click the file monopile_parameters.txt.
Geometry 1
The model geometry is available as a parameterized geometry sequence in a separate MPH-file. If you want to build it from scratch, follow the instructions in the section Appendix — Geometry Modeling Instructions. Otherwise load it from file with the following steps.
1
In the Geometry toolbar, click Insert Sequence and choose Insert Sequence.
2
Browse to the model’s Application Libraries folder and double-click the file monopile_geom_sequence.mph.
3
In the Geometry toolbar, click  Build All.
4
Click the  Zoom Extents button in the Graphics toolbar.
5
Click the  Wireframe Rendering button in the Graphics toolbar.
Materials
Load the Seawater electrolyte material from the Corrosion Material Library as follows:
Add Material
1
In the Home toolbar, click  Add Material to open the Add Material window.
2
Go to the Add Material window.
3
In the tree, select Corrosion>Electrolytes>Seawater.
4
Right-click and choose Add to Component 1 (comp1).
The Seawater entry contains salinity and temperature-dependent conductivity data. The temperature will be taken from the Default Model Inputs that you will define later. The salinity is set to a constant value of 3.5%, but may be altered on the Seawater node itself.
5
In the Home toolbar, click  Add Material to close the Add Material window.
Materials
Seawater (mat1)
1
In the Settings window for Material, locate the Geometric Entity Selection section.
2
Click  Clear Selection.
3
Select Domain 2 only.
Mud
1
In the Model Builder window, right-click Materials and choose Blank Material.
2
In the Settings window for Material, type Mud in the Label text field.
3
Select Domain 1 only.
4
Locate the Material Contents section. In the table, enter the following settings:
Property
Variable
Value
Unit
Property group
Electrolyte conductivity
sigmal_iso ; sigmalii = sigmal_iso, sigmalij = 0
sigma_mud
S/m
Electrolyte conductivity
Global Definitions
Default Model Inputs
Set up the temperature value used in the model.
1
In the Model Builder window, under Global Definitions click Default Model Inputs.
2
In the Settings window for Default Model Inputs, locate the Browse Model Inputs section.
3
In the tree, select General>Temperature (K) - minput.T.
4
Find the Expression for remaining selection subsection. In the Temperature text field, type T.
Definitions
Top
1
In the Definitions toolbar, click  Cylinder.
2
In the Settings window for Cylinder, type Top in the Label text field.
3
Locate the Geometric Entity Level section. From the Level list, choose Boundary.
4
Locate the Size and Shape section. In the Outer radius text field, type 10.
5
In the Top distance text field, type 0.1.
6
In the Bottom distance text field, type -20.1.
7
Locate the Output Entities section. From the Include entity if list, choose Entity inside cylinder.
Middle
1
Right-click Top and choose Duplicate.
2
In the Settings window for Cylinder, type Middle in the Label text field.
3
Locate the Size and Shape section. In the Top distance text field, type 0.
4
In the Bottom distance text field, type -40.
5
Locate the Position section. In the z text field, type -15.
Bottom
1
Right-click Middle and choose Duplicate.
2
In the Settings window for Cylinder, type Bottom in the Label text field.
3
Locate the Size and Shape section. In the Bottom distance text field, type -60.
4
Locate the Position section. In the z text field, type -30.
Middle and Bottom
1
In the Definitions toolbar, click  Union.
2
In the Settings window for Union, locate the Geometric Entity Level section.
3
From the Level list, choose Boundary.
4
In the Label text field, type Middle and Bottom.
5
Locate the Input Entities section. Under Selections to add, click  Add.
6
In the Add dialog box, in the Selections to add list, choose Middle and Bottom.
7
Click OK.
Cathodic Protection (cp)
1
In the Model Builder window, under Component 1 (comp1) click Cathodic Protection (cp).
2
In the Settings window for Cathodic Protection, locate the Domain Selection section.
3
In the list, select 3.
4
Click  Remove from Selection.
5
Select Domains 1 and 2 only.
Protected Metal Surface - Coated Steel
1
In the Physics toolbar, click  Boundaries and choose Protected Metal Surface.
2
In the Settings window for Protected Metal Surface, type Protected Metal Surface - Coated Steel in the Label text field.
3
Locate the Boundary Selection section. From the Selection list, choose Top.
4
Locate the Oxygen Reduction Current Density section. In the iO2 text field, type ilim_O2.
Electrode Surface - Uncoated Steel
1
In the Physics toolbar, click  Boundaries and choose Electrode Surface.
2
In the Settings window for Electrode Surface, type Electrode Surface - Uncoated Steel in the Label text field.
3
Locate the Boundary Selection section. From the Selection list, choose Middle and Bottom.
Electrode Reaction 1 - Steel Oxidation
1
In the Model Builder window, click Electrode Reaction 1.
2
In the Settings window for Electrode Reaction, type Electrode Reaction 1 - Steel Oxidation in the Label text field.
3
Locate the Equilibrium Potential section. In the Eeq text field, type Eeq_Fe.
4
Locate the Electrode Kinetics section. From the Kinetics expression type list, choose Anodic Tafel equation.
5
In the i0 text field, type i0_Fe.
6
In the Aa text field, type A_Fe.
Electrode Surface - Uncoated Steel
In the Model Builder window, click Electrode Surface - Uncoated Steel.
Electrode Reaction 2 - Oxygen Reduction (Sea)
1
In the Physics toolbar, click  Attributes and choose Electrode Reaction.
2
In the Settings window for Electrode Reaction, type Electrode Reaction 2 - Oxygen Reduction (Sea) in the Label text field.
3
Locate the Boundary Selection section. Click  Clear Selection.
4
From the Selection list, choose Middle.
5
Locate the Electrode Kinetics section. From the iloc,expr list, choose User defined. In the associated text field, type ilim_O2.
Electrode Reaction 3 - Oxygen Reduction (Mud)
1
Right-click Electrode Reaction 2 - Oxygen Reduction (Sea) and choose Duplicate.
2
In the Settings window for Electrode Reaction, type Electrode Reaction 3 - Oxygen Reduction (Mud) in the Label text field.
3
Locate the Boundary Selection section. From the Selection list, choose Bottom.
4
Locate the Electrode Kinetics section. In the iloc,expr text field, type ilim_O2_mud.
Sacrificial Edge Anode 1
1
In the Physics toolbar, click  Edges and choose Sacrificial Edge Anode.
2
In the Settings window for Sacrificial Edge Anode, locate the Edge Selection section.
3
From the Selection list, choose Anodes.
4
Locate the Sacrificial Anode Properties section. In the Q0 text field, type AnodeCap.
5
In the r0 text field, type R0.
6
In the rend text field, type Rf.
Electrode Reaction 1
1
In the Model Builder window, click Electrode Reaction 1.
2
In the Settings window for Electrode Reaction, locate the Equilibrium Potential section.
3
In the Eeq text field, type Eeq_AlZn.
Symmetry 1
1
In the Physics toolbar, click  Boundaries and choose Symmetry.
2
Select Boundaries 2, 4, and 266 only.
Initial Values 1
1
In the Model Builder window, click Initial Values 1.
2
In the Settings window for Initial Values, locate the Initial Values section.
3
In the phil text field, type -Eeq_AlZn.
Mesh 1
Size
1
In the Model Builder window, under Component 1 (comp1) right-click Mesh 1 and choose Edit Physics-Induced Sequence.
2
In the Settings window for Size, locate the Element Size section.
3
Click the Custom button.
4
Locate the Element Size Parameters section. In the Minimum element size text field, type 0.05.
5
In the Curvature factor text field, type 0.4.
Size 1
1
In the Model Builder window, right-click Free Tetrahedral 1 and choose Size.
2
In the Settings window for Size, locate the Geometric Entity Selection section.
3
From the Geometric entity level list, choose Edge.
4
From the Selection list, choose Anodes.
5
Locate the Element Size section. From the Predefined list, choose Extremely fine.
6
Click the Custom button.
7
Locate the Element Size Parameters section. Select the Maximum element size check box.
8
In the associated text field, type 0.1.
9
Click  Build All.
Study 1
Step 1: Time Dependent
1
In the Model Builder window, under Study 1 click Step 1: Time Dependent.
2
In the Settings window for Time Dependent, locate the Study Settings section.
3
From the Time unit list, choose a.
4
In the Output times text field, type range(0,1,12).
5
In the Model Builder window, click Study 1.
6
In the Settings window for Study, locate the Study Settings section.
7
Clear the Generate default plots check box.
8
In the Home toolbar, click  Compute.
Results
Mirror 3D 1
1
In the Model Builder window, expand the Results node.
2
Right-click Results>Datasets and choose More 3D Datasets>Mirror 3D.
3
In the Settings window for Mirror 3D, locate the Plane Data section.
4
From the Plane list, choose ZX-planes.
Steel Electrode Potential
1
In the Results toolbar, click  3D Plot Group.
2
In the Settings window for 3D Plot Group, type Steel Electrode Potential in the Label text field.
3
Locate the Data section. From the Dataset list, choose Mirror 3D 1.
4
Locate the Plot Settings section. Clear the Plot dataset edges check box.
Surface 1
1
Right-click Steel Electrode Potential and choose Surface.
2
In the Settings window for Surface, click Replace Expression in the upper-right corner of the Expression section. From the menu, choose Component 1 (comp1)>Cathodic Protection>cp.Evsref - Electrode potential vs. adjacent reference - V.
3
In the Steel Electrode Potential toolbar, click  Plot.
Line 1
1
In the Model Builder window, right-click Steel Electrode Potential and choose Line.
2
In the Settings window for Line, locate the Expression section.
3
In the Expression text field, type 1.
4
Click to expand the Title section. From the Title type list, choose None.
5
Locate the Coloring and Style section. From the Line type list, choose Tube.
6
In the Tube radius expression text field, type cp.redge.
7
Select the Radius scale factor check box.
8
From the Coloring list, choose Uniform.
9
From the Color list, choose Gray.
Steel Electrode Potential
1
Click the  Zoom Extents button in the Graphics toolbar.
2
In the Model Builder window, click Steel Electrode Potential.
3
In the Settings window for 3D Plot Group, locate the Data section.
4
From the Time (a) list, choose 0.
5
In the Steel Electrode Potential toolbar, click  Plot.
The Electrode Potential vs. Adjacent reference at time t = 0 a should look like Figure 2.
6
From the Time (a) list, choose 12.
7
In the Steel Electrode Potential toolbar, click  Plot.
The Electrode Potential vs. Adjacent reference at time t = 12 a should look like Figure 3.
Iron Dissolution Current Density
1
Right-click Steel Electrode Potential and choose Duplicate.
2
In the Settings window for 3D Plot Group, type Iron Dissolution Current Density in the Label text field.
Surface 1
1
In the Model Builder window, expand the Iron Dissolution Current Density node, then click Surface 1.
2
In the Settings window for Surface, click Replace Expression in the upper-right corner of the Expression section. From the menu, choose Component 1 (comp1)>Cathodic Protection>Electrode kinetics>cp.iloc_er1 - Local current density - A/m².
3
In the Iron Dissolution Current Density toolbar, click  Plot.
4
Click the  Zoom Extents button in the Graphics toolbar.
Iron Dissolution Current Density
1
In the Model Builder window, click Iron Dissolution Current Density.
2
In the Settings window for 3D Plot Group, locate the Data section.
3
From the Time (a) list, choose 0.
4
In the Iron Dissolution Current Density toolbar, click  Plot.
The local current density at time t = 0 a should look like Figure 5.
5
From the Time (a) list, choose 12.
6
In the Iron Dissolution Current Density toolbar, click  Plot.
The local current density at time t = 12 a should look like Figure 6.
Cathodic Protection (cp)
Electrode Surface - Uncoated Steel
1
In the Model Builder window, under Component 1 (comp1)>Cathodic Protection (cp) click Electrode Surface - Uncoated Steel.
2
In the Settings window for Electrode Surface, locate the Electrode Phase Potential Condition section.
3
From the Electrode phase potential condition list, choose External short.
4
In the R text field, type R_Tp.
Study 1
In the Home toolbar, click  Compute.
Results
Iron Dissolution Current Density
1
In the Model Builder window, under Results click Iron Dissolution Current Density.
2
In the Iron Dissolution Current Density toolbar, click  Plot.
The local current density after introducing external short at time t = 12 a should look like Figure 7.
Appendix — Geometry Modeling Instructions
From the File menu, choose New.
New
In the New window, click  Model Wizard.
Model Wizard
1
In the Model Wizard window, click  3D.
2
Click  Done.
Geometry 1
Cone 1 (cone1)
1
In the Geometry toolbar, click  Cone.
2
In the Settings window for Cone, locate the Size and Shape section.
3
In the Bottom radius text field, type 2.
4
In the Height text field, type 80.
5
In the Top radius text field, type 1.6.
6
Locate the Position section. In the z text field, type -80.
7
Click  Build Selected.
8
Click the  Wireframe Rendering button in the Graphics toolbar.
Cone 2 (cone2)
1
In the Geometry toolbar, click  Cone.
2
In the Settings window for Cone, locate the Size and Shape section.
3
In the Bottom radius text field, type 2.
4
In the Height text field, type 20.
5
In the Top radius text field, type 1.5.
6
Locate the Position section. In the z text field, type -15.
7
Click  Build Selected.
Work Plane 1 (wp1)
1
In the Geometry toolbar, click  Work Plane.
2
In the Settings window for Work Plane, locate the Plane Definition section.
3
From the Plane list, choose xz-plane.
4
In the y-coordinate text field, type -0.4.
5
Click to expand the Local Coordinate System section. Click to collapse the Local Coordinate System section.
Work Plane 1 (wp1)>Plane Geometry
In the Model Builder window, click Plane Geometry.
Work Plane 1 (wp1)>Quadratic Bézier 1 (qb1)
1
In the Work Plane toolbar, click  More Primitives and choose Quadratic Bézier.
2
In the Settings window for Quadratic Bézier, locate the Control Points section.
3
In row 1, set xw to 1.1.
4
In row 1, set yw to 3.5.
5
In row 2, set xw to 3.
6
In row 2, set yw to 3.5.
7
In row 3, set xw to 3.
8
In row 3, set yw to 2.
Work Plane 1 (wp1)>Line Segment 1 (ls1)
1
In the Work Plane toolbar, click  More Primitives and choose Line Segment.
2
In the Settings window for Line Segment, locate the Starting Point section.
3
From the Specify list, choose Coordinates.
4
Locate the Endpoint section. From the Specify list, choose Coordinates.
5
Locate the Starting Point section. In the xw text field, type 3.
6
In the yw text field, type 2.
7
Locate the Endpoint section. In the xw text field, type 3.
8
In the yw text field, type -8.
9
In the Work Plane toolbar, click  Build All.
10
Click the  Zoom Extents button in the Graphics toolbar.
Work Plane 2 (wp2)
1
In the Model Builder window, right-click Geometry 1 and choose Work Plane.
2
In the Settings window for Work Plane, locate the Plane Definition section.
3
In the z-coordinate text field, type -8.
Work Plane 2 (wp2)>Plane Geometry
In the Model Builder window, click Plane Geometry.
Work Plane 2 (wp2)>Circle 1 (c1)
1
In the Work Plane toolbar, click  Circle.
2
In the Settings window for Circle, locate the Size and Shape section.
3
In the Radius text field, type 0.1.
4
Locate the Position section. In the xw text field, type 3.
5
In the yw text field, type -0.4.
6
Click  Build Selected.
Sweep 1 (swe1)
1
In the Model Builder window, right-click Geometry 1 and choose Sweep.
2
In the Home toolbar, click  Windows and choose Selection List.
Selection List
1
Go to the Selection List window.
2
In the tree, select wp2>1.
3
Click Add to Selection in the window toolbar.
4
In the Model Builder window, click Sweep 1 (swe1).
5
In the Settings window for Sweep, locate the Spine Curve section.
6
Find the Edges to follow subsection. Click to select the  Activate Selection toggle button.
7
Go to the Selection List window.
8
In the tree, select wp1>1 and wp1>2.
9
Click Add to Selection in the window toolbar.
10
In the Settings window for Sweep, locate the Spine Curve section.
11
Select the Reverse direction check box.
12
Locate the Keep Input section. Clear the Keep input objects check box.
13
Click  Build Selected.
Geometry 1
Copy 1 (copy1)
1
In the Geometry toolbar, click  Transforms and choose Copy.
2
Select the object swe1 only.
3
In the Settings window for Copy, locate the Displacement section.
4
In the y text field, type 0.8.
5
Click  Build Selected.
Cylinder 1 (cyl1)
1
In the Geometry toolbar, click  Cylinder.
2
In the Settings window for Cylinder, locate the Size and Shape section.
3
In the Radius text field, type 2.8.
4
In the Height text field, type 0.1.
5
Locate the Position section. In the z text field, type 2.
6
Click  Build Selected.
Block 1 (blk1)
1
In the Geometry toolbar, click  Block.
2
In the Settings window for Block, locate the Size and Shape section.
3
In the Width text field, type 0.1.
4
In the Depth text field, type 0.8.
5
In the Height text field, type 0.05.
6
Locate the Position section. In the x text field, type 2.95.
7
In the y text field, type -0.4.
8
In the z text field, type -8.
9
Click  Build Selected.
Array 1 (arr1)
In the Geometry toolbar, click  Transforms and choose Array.
Selection List
1
Go to the Selection List window.
2
In the tree, select blk1 (solid).
3
Click Add to Selection in the window toolbar.
4
In the Settings window for Array, locate the Size section.
5
In the z size text field, type 50.
6
Locate the Displacement section. In the z text field, type 0.18.
7
Click  Build Selected.
Geometry 1
Work Plane 3 (wp3)
1
In the Geometry toolbar, click  Work Plane.
2
In the Settings window for Work Plane, locate the Plane Definition section.
3
From the Plane list, choose yz-plane.
4
In the x-coordinate text field, type 3.
Work Plane 3 (wp3)>Plane Geometry
In the Model Builder window, click Plane Geometry.
Work Plane 3 (wp3)>Circle 1 (c1)
1
In the Work Plane toolbar, click  Circle.
2
In the Settings window for Circle, locate the Size and Shape section.
3
In the Radius text field, type 0.08.
4
Locate the Position section. In the xw text field, type -0.4.
5
In the yw text field, type -7.8.
6
Click  Build Selected.
Work Plane 3 (wp3)>Array 1 (arr1)
In the Work Plane toolbar, click  Transforms and choose Array.
Selection List
1
Go to the Selection List window.
2
In the tree, select c1 (solid).
3
Click Add to Selection in the window toolbar.
4
In the Settings window for Array, locate the Size section.
5
In the xw size text field, type 2.
6
In the yw size text field, type 4.
7
Locate the Displacement section. In the xw text field, type 0.8.
8
In the yw text field, type 2.
9
Click  Build Selected.
10
Click the  Zoom Extents button in the Graphics toolbar.
Geometry 1
Extrude 1 (ext1)
1
In the Model Builder window, under Component 1 (comp1) right-click Geometry 1 and choose Extrude.
2
In the Settings window for Extrude, locate the Distances section.
3
In the table, enter the following settings:
Distances (m)
3
4
Select the Reverse direction check box.
5
Click  Build Selected.
Move 1 (mov1)
In the Geometry toolbar, click  Transforms and choose Move.
Selection List
1
Go to the Selection List window.
2
In the tree, select ext1 (solid).
3
Click Add to Selection in the window toolbar.
4
In the Settings window for Move, locate the Displacement section.
5
In the z text field, type 3.
6
Click  Build Selected.
Geometry 1
Union 1 (uni1)
1
In the Geometry toolbar, click  Booleans and Partitions and choose Union.
2
In the Settings window for Union, locate the Union section.
3
Clear the Keep interior boundaries check box.
Selection List
1
Go to the Selection List window.
2
In the tree, select cone2 (solid), swe1 (solid), copy1 (solid), cyl1 (solid), Array 1>arr1(1,1,1) (solid), Array 1>arr1(1,1,2) (solid), Array 1>arr1(1,1,3) (solid), Array 1>arr1(1,1,4) (solid), Array 1>arr1(1,1,5) (solid), Array 1>arr1(1,1,6) (solid), Array 1>arr1(1,1,7) (solid), Array 1>arr1(1,1,8) (solid), Array 1>arr1(1,1,9) (solid), Array 1>arr1(1,1,10) (solid), Array 1>arr1(1,1,11) (solid), Array 1>arr1(1,1,12) (solid), Array 1>arr1(1,1,13) (solid), Array 1>arr1(1,1,14) (solid), Array 1>arr1(1,1,15) (solid), Array 1>arr1(1,1,16) (solid), Array 1>arr1(1,1,17) (solid), Array 1>arr1(1,1,18) (solid), Array 1>arr1(1,1,19) (solid), Array 1>arr1(1,1,20) (solid), Array 1>arr1(1,1,21) (solid), Array 1>arr1(1,1,22) (solid), Array 1>arr1(1,1,23) (solid), Array 1>arr1(1,1,24) (solid), Array 1>arr1(1,1,25) (solid), Array 1>arr1(1,1,26) (solid), Array 1>arr1(1,1,27) (solid), Array 1>arr1(1,1,28) (solid), Array 1>arr1(1,1,29) (solid), Array 1>arr1(1,1,30) (solid), Array 1>arr1(1,1,31) (solid), Array 1>arr1(1,1,32) (solid), Array 1>arr1(1,1,33) (solid), Array 1>arr1(1,1,34) (solid), Array 1>arr1(1,1,35) (solid), Array 1>arr1(1,1,36) (solid), Array 1>arr1(1,1,37) (solid), Array 1>arr1(1,1,38) (solid), Array 1>arr1(1,1,39) (solid), Array 1>arr1(1,1,40) (solid), Array 1>arr1(1,1,41) (solid), Array 1>arr1(1,1,42) (solid), Array 1>arr1(1,1,43) (solid), Array 1>arr1(1,1,44) (solid), Array 1>arr1(1,1,45) (solid), Array 1>arr1(1,1,46) (solid), Array 1>arr1(1,1,47) (solid), Array 1>arr1(1,1,48) (solid), Array 1>arr1(1,1,49) (solid), Array 1>arr1(1,1,50) (solid), and mov1 (solid).
3
Click Add to Selection in the window toolbar.
Geometry 1
Union 1 (uni1)
1
In the Model Builder window, click Union 1 (uni1).
2
In the Settings window for Union, click  Build Selected.
Cylinder 2 (cyl2)
1
In the Geometry toolbar, click  Cylinder.
2
In the Settings window for Cylinder, locate the Size and Shape section.
3
In the Radius text field, type 60.
4
In the Height text field, type 100.
5
Locate the Position section. In the z text field, type -100.
6
Click to expand the Layers section. In the table, enter the following settings:
Layer name
Thickness (m)
Layer 1
60
7
Clear the Layers on side check box.
8
Select the Layers on bottom check box.
9
Click  Build Selected.
Block 2 (blk2)
1
In the Geometry toolbar, click  Block.
2
In the Settings window for Block, locate the Size and Shape section.
3
In the Width text field, type 150.
4
In the Depth text field, type 75.
5
In the Height text field, type 300.
6
Locate the Position section. In the x text field, type -75.
7
In the y text field, type -75.
8
In the z text field, type -150.
9
Click  Build Selected.
Difference 1 (dif1)
In the Geometry toolbar, click  Booleans and Partitions and choose Difference.
Selection List
1
Go to the Selection List window.
2
In the tree, select cone1 (solid), uni1 (solid), and cyl2 (solid).
3
Click Add to Selection in the window toolbar.
4
In the Settings window for Difference, locate the Difference section.
5
Find the Objects to subtract subsection. Click to select the  Activate Selection toggle button.
6
Go to the Selection List window.
7
In the tree, select blk2 (solid).
8
Click Add to Selection in the window toolbar.
Geometry 1
Difference 1 (dif1)
1
In the Model Builder window, click Difference 1 (dif1).
2
In the Settings window for Difference, click  Build Selected.
Delete Entities 1 (del1)
1
In the Model Builder window, right-click Geometry 1 and choose Delete Entities.
2
In the Settings window for Delete Entities, locate the Entities or Objects to Delete section.
3
From the Geometric entity level list, choose Domain.
4
On the object dif1, select Domains 4–7 only.
Global Definitions
Parameters 1
1
In the Model Builder window, under Global Definitions click Parameters 1.
2
In the Settings window for Parameters, locate the Parameters section.
3
In the table, enter the following settings:
Name
Expression
Value
Description
NanodeTp
10
10
Number of anodes around transition piece
NanodeMp
4
4
Number of anodes around monopile
Geometry 1
Polygon 1 (pol1)
1
In the Geometry toolbar, click  More Primitives and choose Polygon.
2
In the Settings window for Polygon, locate the Coordinates section.
3
In the table, enter the following settings:
x (m)
y (m)
z (m)
-2.4
0
-4
-2.3
0
-2
4
Locate the Selections of Resulting Entities section. Find the Cumulative selection subsection. Click New.
5
In the New Cumulative Selection dialog box, type AnodeTp in the Name text field.
6
Click OK.
Rotate 1 (rot1)
1
In the Geometry toolbar, click  Transforms and choose Rotate.
2
In the Settings window for Rotate, locate the Input section.
3
From the Input objects list, choose AnodeTp.
4
Locate the Rotation section. In the Angle text field, type -range(180/NanodeTp,360/NanodeTp,180-180/NanodeTp).
5
Locate the Selections of Resulting Entities section. Find the Cumulative selection subsection. From the Contribute to list, choose AnodeTp.
6
Click  Build Selected.
Copy 2 (copy2)
1
In the Geometry toolbar, click  Transforms and choose Copy.
2
In the Settings window for Copy, locate the Input section.
3
Click  Paste Selection.
4
In the Paste Selection dialog box, type rot1(1) rot1(2) rot1(3) rot1(4) rot1(5) in the Selection text field.
5
Click OK.
6
Select the objects rot1(1), rot1(2), rot1(3), rot1(4), and rot1(5) only.
7
In the Settings window for Copy, locate the Displacement section.
8
In the z text field, type -8.
9
Locate the Selections of Resulting Entities section. Find the Cumulative selection subsection. From the Contribute to list, choose AnodeTp.
10
Click  Build Selected.
Polygon 2 (pol2)
1
In the Geometry toolbar, click  More Primitives and choose Polygon.
2
In the Settings window for Polygon, locate the Coordinates section.
3
From the Data source list, choose Vectors.
4
In the x text field, type 2.5.
5
In the y text field, type 0.
6
In the z text field, type -16 -18.
7
Locate the Selections of Resulting Entities section. Find the Cumulative selection subsection. Click New.
8
In the New Cumulative Selection dialog box, type AnoodeMp in the Name text field.
9
Click OK.
Array 2 (arr2)
1
In the Geometry toolbar, click  Transforms and choose Array.
2
In the Settings window for Array, locate the Input section.
3
From the Input objects list, choose AnoodeMp.
4
Locate the Size section. In the z size text field, type 4.
5
Locate the Displacement section. In the z text field, type -6.
6
Click  Build Selected.
Rotate 2 (rot2)
1
In the Geometry toolbar, click  Transforms and choose Rotate.
2
In the Settings window for Rotate, locate the Input section.
3
Click  Paste Selection.
4
In the Paste Selection dialog box, type arr2(1,1,1) arr2(1,1,2) arr2(1,1,3) arr2(1,1,4) in the Selection text field.
5
Click OK.
6
Select the objects arr2(1,1,1), arr2(1,1,2), arr2(1,1,3), and arr2(1,1,4) only.
7
In the Settings window for Rotate, locate the Rotation section.
8
In the Angle text field, type range(180/NanodeMp,360/NanodeMp,180-180/NanodeMp).
9
Locate the Selections of Resulting Entities section. Find the Cumulative selection subsection. From the Contribute to list, choose AnoodeMp.
10
Click  Build Selected.
Anodes
1
In the Geometry toolbar, click  Selections and choose Union Selection.
2
In the Settings window for Union Selection, type Anodes in the Label text field.
3
Locate the Geometric Entity Level section. From the Level list, choose Edge.
4
Locate the Input Entities section. Click  Add.
5
In the Add dialog box, in the Selections to add list, choose AnodeTp and AnoodeMp.
6
Click OK.
Rotate 3 (rot3)
1
In the Geometry toolbar, click  Transforms and choose Rotate.
2
In the Settings window for Rotate, locate the Input section.
3
Click  Paste Selection.
4
In the Paste Selection dialog box, type del1 rot1(1) rot1(2) rot1(3) rot1(4) rot1(5) copy2(1) copy2(2) copy2(3) copy2(4) copy2(5) del1 rot1(1) rot1(2) rot1(3) rot1(4) rot1(5) rot2(1) rot2(2) rot2(3) rot2(4) rot2(5) rot2(6) rot2(7) rot2(8) in the Selection text field.
5
Click OK.
6
Click in the Graphics window and then press Ctrl+A to select all objects.
7
In the Settings window for Rotate, locate the Rotation section.
8
In the Angle text field, type 180.
9
Click  Build Selected.