In either case, you can change the value if you want to apply a specific value locally. In such cases, the maximum size comes from the larger value of the global controls (that is, Max Size or Element Size, as described above) OR, the largest scoped body size or face size that Patch Independent is also scoped to. A scoped edge size is not respected if it is larger than either the global size or the size on an attached face. With the Patch Independent mesh method, scoped body sizing is supported as follows: – If a local body size is defined and it is smaller than the global maximum size, the scoped body size will be assigned inside the volume. – If the global maximum size is smaller than any scoped body, face or edge sizing, the global maximum size (Element Size when Advanced Size Function is off; Max Size when Advanced Size Function is on) will be changed to be the same as the largest sizing within the mesher. For example, if Patch Independent is defined on two bodies, and the setup is as follows: → Global Max Size = 4 → Local body size scoped to Body1 = 8 → No local body size is scoped to Body2 The Patch Independent maximum size will be 8, and the global Max Size of 4 will be used for the sizing of Body2. Note The maximum element size inside the volume of Body2 could grow to 8. Since setting local sizings affects the largest element size in the model, it is recommended to avoid setting local sizes that are larger than the global maximum size. • Approx Number of Elements - Prescribes an approximate number of elements for the mesh. The default is 5.0E+05. Specifying a prescribed number of elements for the Patch Independent method is applicable only if the method is being applied to a single part. • Feature Angle - Specifies the minimum angle at which geometry features will be captured. If the angle between two faces is less than the specified Feature Angle, the edge between the faces will be ignored, and the nodes will be placed without respect to that edge. If the angle between two faces is greater than the Feature Angle, the edge should be retained and mesh aligned and associated with it (note the edge could be ignored due to defeaturing, etc.). You can specify a value from 0 (capture most edges) to 90 (ignore most edges) degrees or accept the default of 30 degrees. • Mesh Based Defeaturing - Ignores edges based on size. Off by default. If set to On, a Defeaturing Tolerance field appears where you may enter a numerical value greater than 0.0. By default, the value of this local Defeaturing Tolerance field is the same as the global Defeaturing Tolerance (p. 100). If you specify a different value here, it will override the global value. Specifying a value of 0.0 here resets the tolerance to its default. If multiple Patch Independent tetra mesh method controls are defined with different tolerances, the smallest tolerance is respected. There are several basic cases, including the following: – A small hole with a diameter smaller than the tolerance as shown below. Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. 130 Local Mesh Controls No edges are dropped. You should defeature manually in this case. – Two approximately parallel spaced edges (fillet or chamfer), as shown below. To determine whether a face is a fillet/chamfer, the Patch Independent mesher evaluates the face's geometric features. To be considered a fillet/chamfer: → A face must be at least twice as long as it is wide. → A fillet/chamfer has either three or four sides (that is, two long sides and one or two short sides), all with angles <= 135 degrees. In the case of a fillet, which is a curved or rounded face, the angle between the fillet and a face at- tached to one of its long sides is 0 degrees (not 180 degrees). In contrast, a chamfer is a planar face and the angle between the chamfer and a face attached to one of its long sides is larger than 0 degrees. For defeaturing of fillets/chamfers, the mesher considers the fillet/chamfer face as well as the faces adjacent to it (i.e., the faces attached to its long sides). The dihedral angles between these faces are evaluated to determine whether the attached edges of adjacent faces will be respected (that is, whether nodes will be placed with respect to the edges at the long sides of the fillet/chamfer). There are three dihedral angles occurring at a fillet/chamfer: → One dihedral angle occurs between the two faces “touching,” or adjacent to, the fillet/chamfer face. When this angle is compared with the Feature Angle, the angle is measured between the face normals at the imaginary edge where the two faces (virtually) meet. → Two dihedral angles occur between the fillet/chamfer face and the respective faces “touching,” or adjacent to, the two long sides of the fillet/chamfer. The angles are evaluated as the angles between the face normals at the common edge of the fillet/chamfer and the attached face. Defeaturing occurs as follows: 131 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. Setting the Method Control for Solid Bodies → If the angle between the two faces adjacent to the fillet/chamfer face is greater than the Feature Angle, and the angles between the fillet/chamfer face and the faces attached to its long sides are less than the Feature Angle, and the minimum fillet/chamfer width is greater than the De- featuring Tolerance, both long sides/edges are respected. → If the angle between the two faces adjacent to the fillet/chamfer face is greater than the Feature Angle, and the angles between the fillet/chamfer face and the faces attached to its long sides are less than the Feature Angle, and the minimum fillet/chamfer width is less than the Defea- turing Tolerance, only one long side/edge is respected. → If only one angle between the fillet/chamfer face and the faces attached to its long sides is greater than the Feature Angle, only one long side/edge is respected. → If none of the angles are greater than the Feature Angle, none of the long sides/edges are re- spected. The following series of figures illustrates fillet/chamfer detection. In this example, a cross-section is revolved. The top and bottom of the section are identical, except the bottom has fillets/chamfers at each corner and the top does not. Because the definition of a fillet/chamfer is somewhat general, two cases are presented, each with a different angle of revolution. The angle of revolution is 5 degrees in the first case, as shown below. In this case, only the small faces fit the criteria of fillets/chamfers. In the second case, the angle of revolution is 180 degrees, as shown below. In this case, all faces fit the criteria of fillets/chamfers, except for the front/back faces of the extrusion. Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. 132 Local Mesh Controls The figure below shows the angles that are considered for fillet/chamfer detection, and the small faces that are found to be fillets/chamfers. As described earlier, the angles that are considered for a given fillet/chamfer are 1) the angle between adjacent fillet/chamfer faces and 2) the two angles attached to the fillet/chamfer. Notice the angles in the figure below. 133 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. Setting the Method Control for Solid Bodies Notice the settings shown below, with Feature Angle set to 30 and Mesh Based Defeaturing turned off. In the figure below, the highlighted edges are the edges that are ignored with the settings shown above. All edges are captured except for locations where the angle between faces or adjacent fil- let/chamfer faces (two bottom edges) is 20 degrees. Changing the Feature Angle to a value below 20 will result in the mesher capturing those edges, while increasing the angle will result in more edges being ignored. In the settings shown below, Feature Angle is changed to 80 but the other settings used before are retained. Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. 134 Local Mesh Controls In the figure below, the highlighted edges are the edges that are ignored with the settings shown above. All edges are ignored except for those at angles of 90 degrees, both with or without fil- lets/chamfers. Now consider the settings shown below. Here the Feature Angle is set back to 30, but Mesh Based Defeaturing is turned on. Both the Defeaturing Tolerance and the Min Size Limit are set to 2.5 mm, which is larger than the bottom fillets/chamfers. In the figure below, the highlighted edges are the edges that are ignored with the settings shown above. The same edges as before are ignored due to the feature angle, but in addition every other edge along the bottom fillets/chamfers is ignored. 135 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. Setting the Method Control for Solid Bodies The last part of this example involves the case in which the angle of revolution is 180 degrees. Once again the Feature Angle is set to 80 but Mesh Based Defeaturing is turned off. In the figure below, the highlighted edges are the edges that are ignored. With the settings shown above and the longer extrusion, more faces are found to be fillets/chamfers when compared to the case of the shorter extrusion. In comparison, the bottom section is identical as all faces are found to be fillets/chamfers (so the meshing behavior does not change). However, with the inclusion of all faces on top being considered chamfers, the meshing behavior does change. Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. 136 Local Mesh Controls The following series of figures shows examples of the Patch Independent Tetrahedron mesher with various settings. Figure (a) shows the base geometry. Figure: Example (a) Showing Base Geometry Figures (b) through (f) below show examples of the Patch Independent Tetrahedron mesher under the conditions noted. 137 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. Setting the Method Control for Solid Bodies Figure: Example (b) Min Size Limit (Described Below) Set to 1 Figure: Example (c) Min Size Limit (Described Below) Set to 0.5 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. 138 Local Mesh Controls Figure: Example (d) Defeaturing Tolerance Set to 1 Figure: Example (e) Defeaturing Tolerance Set to 1 and Midside Nodes Dropped 139 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc. and its subsidiaries and affiliates. Setting the Method Control for Solid Bodies [...]... is Quad/Tri Hex dominant meshing adds the most value under the following conditions: • Meshing bodies with large amounts of interior volume • Meshing bodies that transition from sweepable bodies in a body that has been decomposed for sweeping However, it is better to use Body/Face Sizing to obtain more uniform face meshing, which leads to more hexes by volume Hex dominant meshing adds little value... All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 1 45 Local Mesh Controls is set to 5, and you have curvature in your model that warrants curvature based mesh refinement down to the minimum element size, you will see that the largest elements are not size 5 but size 4 This happens because in order to maintain elements at the minimum... Sets options for writing ANSYS ICEM CFD files Refer to Writing ANSYS ICEM CFD Files (p 47) for details Note For detailed information about MultiZone, refer to MultiZone Meshing (p 212) For general information on applying MultiZone in combination with other mesh method controls, refer to Mesh Control Interaction Tables (p 261) Notes on Scoping for the MultiZone Mesh Method 154 Release 13.0 - © SAS IP,... edges, faces, and bodies means that the size control will be affected by proximity, curvature, and local re -meshing during the meshing process If Use Advanced Size Function (p 59 ) is off: 162 Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Curvature Normal Angle • Choosing Hard on a face/body means... proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Setting the Method Control for Solid Bodies • Meshing thin complicated bodies (like a cellular phone case) The number of elements may actually increase compared to a tetrahedron mesh since the element size must be much smaller for this class of body when using hex dominant meshing to create well shaped hexes • A... You can define virtual split edges to achieve consistent lengths for these edges (see Creating Virtual Split Edges (p 2 85) ) Also see Sizing Control (p 157 ) for more information Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 149 Local Mesh Controls • Sweep Bias Type - Specify bias in the same manner... Free Mesh Type = Tetra (p 152 ) shows a MultiZone mesh that was generated when Free Mesh Type was set to Tetra Notice the upper section that was able to be mapped meshed, and the lower section that was free meshed because it could not be mapped meshed Refer to Patch Conforming Algorithm for Tetrahedrons Method Control (p 1 25) for more information Figure: Free Mesh Type = Tetra – 152 Hexa Dominant — Regions... proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 153 Local Mesh Controls • Source - Select the faces that need to be imprinted for proper geometry decomposition The faces you select can be either “sources” or “targets,” but all of them will be treated as sources by MultiZone, as shown in Figure: Source Face Selection for MultiZone (p 154 ) Note To make source face selection... methods in a multibody part, and the bodies will be meshed with conformal mesh Refer to Conformal Meshing Between Parts (p 7) for information about conformal meshing and mesh method interoperability Notes on Virtual Topologies and the Patch Independent Mesher Virtual topologies may affect the success of meshing with the Patch Independent tetra mesh method Because virtual topologies are often a coarse... option, refer to Method Controls and Element Midside Nodes Settings (p 122) Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 155 Local Mesh Controls Uniform Quad/Tri Method Control If you select the Uniform Quad/Tri method, a uniform mesh of quads and triangles is created over the entire part of the selected . The default is Quad/Tri. Hex dominant meshing adds the most value under the following conditions: • Meshing bodies with large amounts of interior volume. • Meshing bodies that transition from sweepable. Edges (p. 2 85) ). Also see Sizing Control (p. 157 ) for more information. 149 Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information of ANSYS, Inc are found to be fillets/chamfers (so the meshing behavior does not change). However, with the inclusion of all faces on top being considered chamfers, the meshing behavior does change. Release 13.0