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Release 11.0 Documentation for ANSYS
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Low-Frequency Guide | Chapter 13. Electrostatic Field Analysis (h-Method) |

13.9. Doing an Electrostatic Analysis Using Trefftz Method (GUI Method)

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As shown below, you can use GUI menu paths to perform the example analysis of creating a Trefftz domain to solve an open boundary problem in electrostatics.

Step 1: Start the Analysis

  1. Activate the ANSYS launcher.

  2. Select the ANSYS simulation environment, choose your license, and click Run.

  3. When the Graphical User Interface is fully active, choose Utility Menu> File> Change Title. A dialog box appears.

  4. Enter the title text, Sphere to Infinity Capacitance

  5. Click on OK.

  6. Choose Main Menu> Preferences. The Preference dialog box appears.

  7. Click Electric on.

  8. Click on OK.

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Step 2: Define Analysis Parameters

  1. Choose menu path Utility Menu> Parameters> Scalar Parameters. The Parameters dialog box appears.

  2. Type in the parameter values shown below. (Press ENTER after entering each value.)

    n = 5
    r1 = 100
    r2 = 300
    r3 = 125

  3. Click on Close to close the dialog box.

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Step 3: Define Element Types

  1. Choose Main Menu> Preprocessor> Element Type> Add/Edit/Delete. The Element Types dialog box appears.

  2. Click on Add. The Library of Element Types dialog box appears.

  3. In the scrollable fields, click on (highlight) Electrostatic and 3D Tet 123 (SOLID123).

  4. Click on OK. ANSYS returns you to the Element Types dialog box.

  5. Click on Close to close the Element Types dialog box.

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Step 4: Define Material Properties

  1. Choose Main Menu> Preprocessor> Material Props> Electromag Units. The Electromagnetic Units dialog box appears.

  2. Select the User-Defined option button and click on OK. A Electromagnetics Units text entry box appears.

  3. Enter 8.854e-6 for the free-space permittivity (μMKSV units) and click on OK.

  4. Choose Main Menu> Preprocessor> Material Props> Material Models. The Define Material Model Behavior dialog box appears.

  5. In the Material Models Available window, double-click on the following options: Electromagnetics, Relative Permittivity, Constant. A dialog box appears.

  6. Enter 1 for PERX (Relative permittivity), and click on OK. Material Model Number 1 appears in the Material Models Defined window on the left.

  7. Choose menu path Material>Exit to remove the Define Material Model Behavior dialog box.

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Step 5: Create Solid Model

  1. Choose Main Menu> Preprocessor> Modeling> Create> Volumes> Sphere> By Dimensions. The Create Sphere by Dimensions dialog box appears.

  2. In the “RAD1” field, enter r1, in the “RAD2” field, enter 0, in the “THETA1” field, enter 0, in the “THETA2” field, enter 90, and click on OK.

  3. Choose Utility Menu> PlotCtrls> Pan, Zoom, Rotate. A Pan-Zoom-Rotate dialog box appears.

  4. Click on the Iso button, then click on Close. The ANSYS Graphics Window displays the block.

  5. Choose Main Menu> Preprocessor> Modeling> Create> Volumes> Block> By Dimensions. The create Block by Dimensions dialog box appears.

  6. In the “X coordinates” field, enter 0, r2, in the “Y coordinates” field, enter 0, r2, and in the “Z coordinates” field, enter 0, r2.

  7. Choose Main Menu> Preprocessor> Modeling> Operate> Booleans> Subtract> Volumes. The Subtract Volumes picking menu appears.

  8. Pick (or enter in the picker) the block volume (volume 2) and click on OK. The Subtract Volumes picking menu reappears.

  9. Pick (or enter in the picker) the spherical volume (volume 1) and click on OK.

  10. Choose Main Menu> Preprocessor> Modeling> Reflect> Volumes. The Reflected Volumes picking menu appears.

  11. Click on Pick All. The Reflected Volumes dialog box appears.

  12. Check that the Y-Z plane is selected and click on OK.

  13. Choose Main Menu> Preprocessor> Modeling> Reflect> Volumes. The Reflected Volumes picking menu appears.

  14. Click on Pick All. The Reflected Volumes dialog box appears.

  15. Select the X-Z plane and click on OK.

  16. Choose Main Menu> Preprocessor> Modeling> Reflect> Volumes. The Reflected Volumes picking menu appears.

  17. Click on Pick All. The Reflected Volumes dialog box appears.

  18. Select the X-Y plane and click on OK.

  19. Choose Main Menu> Preprocessor> Numbering Ctrls> Merge Items. A Merge Coincident or Equivalently Defined Items dialog box appears.

  20. Set the “Type of Item to be merge (Label)” to All and click on OK.

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Step 6: Mesh the Model and Create a Finite Element Model Component

  1. Choose Main Menu> Preprocessor> Meshing> MeshTool. The MeshTool appears.

  2. Click on the Set Global Size Controls button. A Global Element Sizes dialog box appears.

  3. In the “No. of Element Divisions (NDIV)” field, enter n, and click on OK.

  4. Make sure that Volumes, Tet, and Free are selected in the MeshTool.

  5. Click MESH. The Mesh Volumes picking menu appears.

  6. Click on Pick All. The display changes to show the meshed volumes. Click Close to close the MeshTool.

  7. Choose menu path Utility Menu> Select> Comp/Assembly> Create Component. The Create Component dialog box appears.

  8. In the “Component Name (Cname)” field enter vol, set the “Component is made of (Entity)” to volumes, and click on OK.

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Step 7: Apply Infinite Surface Flag to Exterior Surface of Finite Element Region

  1. Choose menu path Utility Menu> Select> Entities. The Select Entities dialog box appears.

  2. Set the top box to nodes and the second box to By Location. Enter r2 in the “Min/Max” field, select X coordinates, and click on OK.

  3. Choose menu path Utility Menu> Select> Entities. The Select Entities dialog box appears.

  4. Enter -r2 in the “Min/Max” field, change the selection type radio button to Also Sele, and click on Apply.

  5. Enter r2 in the “Min/Max” field, change the coordinates radio button to Y coordinates, and click on Apply.

  6. Enter -r2 in the “Min/Max” and click on Apply.

  7. Enter r2 in the “Min/Max” field, change the coordinates radio button to Z coordinates, and click on Apply.

  8. Enter -r2 in the “Min/Max” field and click on OK.

  9. Choose menu path Main Menu> Preprocessor> Loads> Define Loads> Apply> Electric> Flag> Infinite Surf> On Nodes. The Apply INF on Nodes dialog box appears.

  10. Click on Pick All.

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Step 8: Create a Spherical Conductor Surface Node Component

  1. Choose menu path Utility Menu> WorkPlane> Change Active CS to> Global Spherical.

  2. Choose menu path Utility Menu> Select> Entities. The Select Entities dialog box appears.

  3. Check that the top box is set to nodes and the second box is set to By Location. Change the coordinates radio button to X coordinates, change the selection type radio button to From Full, enter r1 in the “Min/Max” field, and click on OK.

  4. Choose menu path Utility Menu> Select> Comp/Assembly> Create Component. The Create Component dialog box appears.

  5. In the “Component Name (Cname)” field enter cond1, set the “Component is made of (Entity)” to nodes, and click on OK.

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Step 9: Create Trefftz Nodes and Trefftz Domain

  1. Choose menu path Utility Menu> WorkPlane > Change Active CS to> Global Cartesian.

  2. Choose menu path Main Menu> Preprocessor> Trefftz Domain> TZ Geometry> Create> Volume> Sphere> By Dimensions. The Create Sphere by Dimensions dialog box appears.

  3. In the “Outer Radius (RAD1)” field enter r3. Check that the “Starting angle (THETA1) and Ending angle (THETA2) are 0 and 360 degrees, respectively. Click on OK.

  4. Choose menu path Utility Menu> Select> Comp/Assembly> Select Comp/Assembly. The Select Component or Assembly dialog box appears.

  5. In the “Select Entities belonging to Component or Assembly (CMSEL)” field choose VOL, in the “Type of Selection (Type)” field choose Unselect, and click on OK.

  6. Choose menu path Main Menu> Preprocessor> Trefftz Domain> Mesh TZ Geometry. The Mesh TZ Geometry dialog box appears.

  7. Pick the Trefftz volume (volume 5) and click on OK. The Parameters for mesh of Trefftz domain dialog box appears.

  8. Check that the No. of element divisions (NDIV) is set to 2 and click on OK. A pop-up window displays the results for Trefftz nodes.

  9. Review the results, which show 20 Trefftz nodes have been created, and click on Close.

  10. Choose menu path Utility Menu> Select> Everything.

  11. Main Menu> Preprocessor> Trefftz Domain> Superelement> Generate TZ. A pop-up window displays the results for the Trefftz Domain.

  12. Review the results and click on Close.

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Step 10: Compute Capacitance

  1. Choose menu path Main Menu> Finish.

  2. Choose menu path Main Menu> Solution> Analysis Type> New Analysis. A New Analysis dialog box appears with Steady-State entered for the “Type of Analysis (ANTYPE).”

  3. Click on OK.

  4. Choose menu path Main Menu> Solution> Analysis Type> Analysis Options. The Static or Steady-State Analysis dialog box appears.

  5. Set the “Equation Solver (EQSLV)” to Jacobi Conj Grad and click on OK.

  6. Choose menu path Main Menu> Solution> Solve> Electromagnet> Static Analysis> Capac Matrix. The Capac Matrix dialog box appears.

  7. In the “Symfac Geometric symmetry factor (Symfac)” field, enter 1, in the “Component name identifier (Condname)” field, enter cond, in the “Number of cond components (Ncond)” field, enter 1, in the “Ground Key (Grndkey)” field, enter 1, and click on OK.

  8. Review the results and click on Close.

  9. Choose menu path Main Menu> Finish.

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13.8. Doing an Electrostatic Analysis Using Trefftz Method (Command Method)		Up / HomeNext
Chapter 14. p-Method Electrostatic Analysis
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