Ansoft HFSS Mesh Menu

Transcription

1 Ansoft HFSS After you have seeded your object, you must create the finite element mesh from which the variables and values of your model will be computed. The Mesh menu allows you to: Create or delete a mesh. Display information such as the number of tetrahedra and volumes in your object. Change the display attributes for the mesh. When you choose Mesh from the menu bar, the following menu appears: The following commands are available from the mesh menu: Make Creates a finite element mesh on a seeded object. Delete Deletes the entire mesh. Mesh Info Displays information about the mesh. Show Mesh Turns the mesh display on or off. Display Parameters Displays various aspects of the mesh. Maxwell Online Help System 384 Copyright Ansoft Corporation

2 Settings for Initial Surface Triangulation Ansoft HFSS Use this command to create a finite element mesh from the seedings. If seeds have been defined, they will be used to further refine the mesh. > To create a mesh: 1. Choose. A window appears, asking if you want to reset the faceter settings. 2. If you do not want to reset the faceter settings, choose No. A bar will appear indicating the progress of the mesh created by the Meshmaker. Choose Abort to stop the Meshmaker from creating the mesh. The meshing is finished when the screen is refreshed. If you want to reset the faceter settings, choose Yes. The Settings for Initial Surface Triangulation window appears: Note: The default faceter settings work very well for Ansoft HFSS s adaptive solution algorithm, which is used for a wide variety of problems. The settings should be modified only under unusual circumstances. Maxwell Online Help System 385 Copyright Ansoft Corporation

3 Settings for Initial Surface Triangulation Ansoft HFSS Settings for Initial Surface Triangulation To create a finite element mesh, the Meshmaker first divides all object surfaces into triangles. These triangulated surfaces are called faceted surfaces because a series of straight line segments represents each curved or planar surface. In the meshed sphere below, the white, curved lines represent the sphere s true surfaces and the triangles represent the faceted surfaces. More When an object s surface is non-planar, as shown above, the faceted triangle faces will lie a small distance from the object s true surfaces. This distance is called the surface deviation. The surface deviation is greater near the triangle centers and less near the triangle vertices. The Settings for Initial Surface Triangulation window enables you to alter the shape of each triangle and the surface deviation of the faceted triangle faces from the true surfaces. > To reset the faceter settings: 1. Enter the maximum angular deviation for each type of Cone/Cylinder, Sphere, Torus, and Spline surface in the model in the respective Max angular dev fields. This value is the maximum permitted angular deviation between the normals of the faceted triangles and the normals of the true surfaces they represent. Maxwell Online Help System 386 Copyright Ansoft Corporation

4 Settings for Initial Surface Triangulation Ansoft HFSS Using the same angular surface deviation for large objects and small objects will result in similar faceting for similar surfaces, without regard to the object s size. For example, if the maximum angular deviation of a cylinder is set to 30 degrees, 12 faceted triangles for the cylindrical surface will be created, with no regard for the cylinder s radius. By default, the values are set to 15 degrees. Note that you cannot change the angular deviation for a plane because its faceted triangles lie exactly on the true surfaces. 2. Enter the maximum surface deviation for each surface type in its respective Max surf deviation field. This value is the maximum permitted distance between the faceted triangle faces and the true surfaces. Using the same surface deviation for large objects and small objects will result in a large number of faceted triangles for the large objects and a smaller number of faceted triangles for the small objects. For example, if a maximum surface deviation of a sphere is set to 0.5 mm, more faceted triangles are required for a sphere with a 10-mm diameter than a sphere with a 100-mm diameter. By default, the values are set to zero. The maximum surface deviation criteria is turned off when the values are set to zero. Note that you cannot change the surface deviation for a plane because the faceted triangles lie exactly on the true surfaces. 3. Enter the maximum aspect ratio for each surface type in its respective Max aspect ratio field. This value determines the shape of the triangles. The higher the value, the thinner the triangles. Values close to one will result in well-formed, wide triangles. By default, the values are set to 20, except for planes, which are set to a default of Choose OK to accept the settings or Cancel to ignore the settings. Optionally, choose Reset to restore the values to their defaults before continuing. A bar will appear indicating the progress of the mesh created by the Meshmaker. Choose Abort to stop the Meshmaker from creating the mesh. The meshing is finished when the screen is refreshed. Maxwell Online Help System 387 Copyright Ansoft Corporation

5 Ansoft HFSS Use this command to delete a mesh you have created. Once you have deleted a mesh, you can reseed or create a different mesh for the object. > To delete a mesh: Choose. The mesh is deleted. Use this command to display the numbers of total tetrahedra, the maximum and minimum volumes, the number of the solids, and the names of the objects in the model. > To display information about the existing mesh: 1. Choose. The Mesh Information window appears. 2. Choose OK to return to the Meshmaker or Help for more information on the mesh. Use this command to toggle the mesh display on and off. A check box appears next to this command if the mesh is shown. > To show the mesh on an object or face: Choose. Choose it again to turn off the mesh. The check box will vanish. Maxwell Online Help System 388 Copyright Ansoft Corporation

6 Ansoft HFSS This command allows you to set the display parameters of the mesh. > To display the mesh: 1. Choose. The Set View Parameters window appears. 2. Choose More to expand the window. 3. Select the Display Type of the mesh: No mesh Show points Show triangles Show tetrahedra Leaves the mesh hidden, which is useful when you want to view the mesh in one window and the model in another. Shows only the points of the tetrahedra in the mesh. Shows the surface triangles of the mesh. This is the default. Displays the full tetrahedra of the finite element mesh. 4. Select the Plot Mode of the mesh: Shaded plot Fills the mesh of the objects in the model with solid colors. Hiddenline plot Displays the shaded surface meshes as wireframed. Wireframe plot Shows only the outlines of the tetrahedra in the mesh. More 5. Enter the Scale Percentage of the mesh in the plot. This value controls how large the tetrahedra of the mesh appear in the plot. For example, if you enter 50 as the scale percentage, the tetrahedra in the mesh will appear to be 50% smaller than they actually are. This is useful when you want to see the edges of the tetrahedra. 6. If you chose Show triangles, select the mesh display on the faces of the objects under On faces: Plot on all faces Plots the mesh on all the faces of all the objects in the model. Plot on selected Plots the mesh on only the selected faces of objects. faces only Plot on unselected Plots the mesh only on the unselected faces of objects. faces only Maxwell Online Help System 389 Copyright Ansoft Corporation

7 Ansoft HFSS 7. Optionally, if you chose Show triangles, or Show tetrahedra, you can choose to plot the mesh inside a box. This is useful when inspecting meshes on arbitrary regions. a. Toggle on Do not plot outside the box. This prevents the Meshmaker from plotting the mesh on objects outside the region of the box. b. Choose Define/Change Box. c. Enter the coordinates of the Box base vertex in the coordinates fields. d. Choose Enter to accept the vertex point or Cancel to ignore the box. e. Enter the dimensions of the box in the Enter box size fields. f. Choose Enter to accept the box dimensions or Cancel to cancel the action. 8. Choose OK to accept your values or Cancel to cancel the command. Maxwell Online Help System 390 Copyright Ansoft Corporation