Edge Layer Mesh Controls
Model, with edge layer and without edge layer, controls to generate layers from selected lines during surface meshing.
Process: Define surface mesh controls (on CAD geometry) → Define edge layer controls → Right-click on surface mesh folder → Mesh.
Edge Global
Global edge mesh controls define edge layer parameters and settings, such as layer element type. These controls are optional. You only have to create them if you want to change any settings.
Entity Selection Parameters
In the Entities field, use the entity selector to select the entities that the mesh control applies to.
The following entities can be selected using the entity selector:
- Lines / Lines regions
- Parent surfaces / Parent surface region
Meshing will only work if surfaces have mesh associated with them.
Edge Layer Parameters
Available parameters vary depending on the Method you select: Simple, Advanced, User Defined.
- Main Parameters
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Parameter Description Basic Surface Mesh Treatment - Fixed
- Prohibit selected elements from being modified.
- Float
- Enable 2D base elements to be modified, if necessary. Generally, 2D base elements with NoBL are modified when refinement zones are defined and/or when the BL imprints on them.
BL Definition When enabled, parameters will be editable and will be applied to all selections. When disabled, a BL definition will not be applied at model level. Local controls will override the BL definition at the model level.
First Layer Thickness Specify the thickness of the first boundary layer. First Layer Thickness Method (A) - Constant
- Enable a constant thickness to be defined for the first boundary layer of the selection.
- As Factor of Base 2D Elements
- Enable a factor, which will be multiplied by the average element size, to be defined. The first layer height for each element equals the average element size multiplied by the factor. This option is useful when the size of 2D elements varies significantly and a constant first layer height is not needed. With this factor, a smooth BL to tetramesh transition for all elements can be achieved.
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Figure 1. First Layer Thickness Method (A)
Growth Rate Determine how rapidly elements can increase in size as they are created further and further away from features. Elements further from the features grow larger with each row.
BL Growth Rate Method (A) - Constant
- Enable a constant ratio to be defined, which determines how boundary layers grow.
- Acceleration
- Enable a growth acceleration for boundary layers to be defined beyond the first few layers. This option acts as a growth rate on the growth rate, but only after the first few initial boundary layers. A Start Acceleration from Layer must be defined first, and then from that layer the acceleration will be started. An Acceleration to the initial growth rate and a Maximum Growth Rate must also be defined.
- Aspect Ratio Based
- Enable the growth rate definition for boundary layers to be based on the defined aspect ratio of the final layer. After the first few initial boundary layers, if this type of growth rate method is selected, the rest of the BL will grow to achieve the user-defined Final layer height/base ratio.
BL Thickness Control (UD) Enable this option to enter either the Number of layers or the Total BL thickness. Second Group (UD) Help to get a smooth transition between BL layers and the tet core more quickly by defining a higher growth rate. Final Layer Height/Base Ratio Define the ratio between the total boundary layer thickness and the average element size of the base surface elements. BL Stopping Criteria (A) Determine what to do when BL has reached the defined criteria for Final Layer Height/Base Ratio. - Chop Off Layers
- Chop off the BL if elements reach the aspect ratio criteria.
- Keep Growing Gr=1
- Allow the BL to grow until the neighboring elements begin to grow, even if elements reach the aspect ratio criteria with GR =1.
Number of Layers (S) Define the total number of layers to be generated using the specified first layer thickness and growth rate. Layer element type Define elements type on layers. Available options are Quads and Trias. - Advanced Parameters
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Parameter Description Boundary Layer Propagation Treatment at Sharp Edges - Node collapse
- Collapse BL at baffles or sharp corners below the defined angle.
- Multiple normal
- Grow multiple normals around baffles or sharp corners below the defined angle. If two adjacent elements enclose an angle smaller than the threshold (sharp edge pointing into the volume), normals will be computed on that edge and the boundary layer will consider those normals.
Entities If multiple normal option is selected, select lines or nodes on which the multiple normal BL needs to be created. If there is no selection and multiple normal option is selected, it will consider features defined by "Sharp edge angle". You can define any angle. Sweep Angle If multiple normal option is selected, sweep angle will define number of BL segments created at defined feature edge. The number of BL segments at the defined edge = 180 / sweep angle. BL is smoother with smaller angles. Sharp Edge Angle Define the threshold of angles below which the BL should be collapsed Auto append neighboring edges If on, automatically append the neighboring selection to avoid early termination of BL Minimum Imprint Angle from BL to Non-BL Control which cases to imprint BL entities on without BL components. If the angle between the BL component and the non-BL component is high, imprinting will create high aspect ratio elements. If the angle between BL and non-BL entities (component elements) is less than the imprint angle or greater than (180-imprint angle), then the BL will collapse rather than imprinting on non-BL entities. Recommended range: 6-10
Max Layer Difference Between Neighbors Control the maximum layer difference between neighboring elements. This parameter helps avoid situations where all BLs collapse at once, and also provides smooth BL transitions in cases of BL truncation. A good value for this parameter is 1/4 of the total BL layers. The value specified also depends on layer height. Recommended range: Depends on how many layers you are growing.
Proximity Maximum BL Compression Enable BL compression, or squeezing, when there is not enough space available for the BL to grow. The BL will try to compress by the max BL compression factor first. For example, if the original total BL height is defined as 1, with a 0.4 max BL compression, the BL layers will try to be compressed until 0.6 of the total height is reached. Once the BL is compressed to this value, the mesher will start chopping off layers if there is not enough space. A value of zero enforces no BL compression, which is useful when you want to maintain the BL height; a value of one enables the maximum possible compression.
Recommended range: 0-0.6
Minimum BL Thickness/Base Ratio Due to close proximity, the BL will sometimes only be able to generate one to two layers (a very small total BL height at that location). At that location, it might be possible that the transition between BL layers and the tetra core is bad. With this factor, if the total BL height is less than the defined factor base size, all of the BL layers will be chopped off. By default, this value is zero, which disables the effects of this parameter.
Minimum Tetcore/Final Layer Height Ratio Control the minimum height of the tet core as a factor of the final layer height. After creating the BL in close proximity, there will be a small space available for tetramesh. This results in high aspect ratio tetra elements.
Recommend value: 1.3 (default)
Boundary Layer Quality Generation Method Controls the growth of boundary layers - Optimize Quality
- Use a set of meshing parameters, which ensures a good quality boundary layer in most cases.
- Optimize Speed
- Choose meshing parameters in a way that the meshing time is minimized and an acceptable boundary layer quality is achieved.
Maximum Cell Skewness Chop off BL cells exceeding the defined maximum cell skewness. This parameter prevents the generation of highly skewed elements. The tetra mesher sometimes creates better quality elements compared to the BL mesher. If your input 2D mesh has bad element quality and topology, it is recommended that you define a higher value.
Recommended range: 0.8 - 0.95
Minimum Normalized Jacobian Chop off BL cells exceeding the defined minimum normalized Jacobian. This parameter prevents the generation of negative elements. Recommended range: 0.05 - 0.2
Edge With Layer
These mesh control define edge layer parameters and settings. You have to select a line on which layers are to be grown and a parent surface which indicates which side of the edge layers needs to be created on.
Entity Selection Parameters
In the Entities field, use the entity selector to select the entities that the mesh control applies to.
The following entities can be selected using the entity selector:
- Lines / Lines regions
- Parent surfaces / Parent surface region
Meshing will only work if surfaces have mesh associated with them.
Edge Layer Parameters
Available parameters vary depending on the Method you select: Simple, Advanced, User Defined.
- Main Parameters
-
Parameter Description Basic Surface Mesh Treatment - Fixed
- Prohibit selected elements from being modified.
- Float
- Enable 2D base elements to be modified, if necessary. Generally, 2D base elements with NoBL are modified when refinement zones are defined and/or when the BL imprints on them.
BL Definition When enabled, parameters will be editable and will be applied to all selections. When disabled, a BL definition will not be applied at model level. Local controls will override the BL definition at the model level.
First Layer Thickness Specify the thickness of the first boundary layer. First Layer Thickness Method (A) - Constant
- Enable a constant thickness to be defined for the first boundary layer of the selection.
- As Factor of Base 2D Elements
- Enable a factor, which will be multiplied by the average element size, to be defined. The first layer height for each element equals the average element size multiplied by the factor. This option is useful when the size of 2D elements varies significantly and a constant first layer height is not needed. With this factor, a smooth BL to tetramesh transition for all elements can be achieved.
-
Figure 2. First Layer Thickness Method (A)
Growth Rate Determine how rapidly elements can increase in size as they are created further and further away from features. Elements further from the features grow larger with each row.
BL Growth Rate Method (A) - Constant
- Enable a constant ratio to be defined, which determines how boundary layers grow.
- Acceleration
- Enable a growth acceleration for boundary layers to be defined beyond the first few layers. This option acts as a growth rate on the growth rate, but only after the first few initial boundary layers. A Start Acceleration from Layer must be defined first, and then from that layer the acceleration will be started. An Acceleration to the initial growth rate and a Maximum Growth Rate must also be defined.
- Aspect Ratio Based
- Enable the growth rate definition for boundary layers to be based on the defined aspect ratio of the final layer. After the first few initial boundary layers, if this type of growth rate method is selected, the rest of the BL will grow to achieve the user-defined Final layer height/base ratio.
BL Thickness Control (UD) Enable this option to enter either the Number of layers or the Total BL thickness. Second Group (UD) Help to get a smooth transition between BL layers and the tet core more quickly by defining a higher growth rate. Final Layer Height/Base Ratio Define the ratio between the total boundary layer thickness and the average element size of the base surface elements. BL Stopping Criteria (A) Determine what to do when BL has reached the defined criteria for Final Layer Height/Base Ratio. - Chop Off Layers
- Chop off the BL if elements reach the aspect ratio criteria.
- Keep Growing Gr=1
- Allow the BL to grow until the neighboring elements begin to grow, even if elements reach the aspect ratio criteria with GR =1.
Number of Layers (S) Define the total number of layers to be generated using the specified first layer thickness and growth rate. - Advanced Parameters
-
Parameter Description Use Global Values Values defined for advanced parameters will be taken from the advanced parameters defined for the model mesh control Maximum BL Compression Enable BL compression, or squeezing, when there is not enough space available for the BL to grow. The BL will try to compress by the max BL compression factor first. For example, if the original total BL height is defined as 1, with a 0.4 max BL compression, the BL layers will try to be compressed until 0.6 of the total height is reached. Once the BL is compressed to this value, the mesher will start chopping off layers if there is not enough space. A value of zero enforces no BL compression, which is useful when you want to maintain the BL height; a value of one enables the maximum possible compression.
Recommended range: 0-0.6
Minimum BL Thickness / Base Ratio Due to close proximity, the BL will sometimes only be able to generate one to two layers (a very small total BL height at that location). At that location, it might be possible that the transition between BL layers and the tetra core is bad. With this factor, if the total BL height is less than the defined factor base size, all of the BL layers will be chopped off. By default, this value is zero, which disables the effects of this parameter.
Edge Without Layer
These mesh controls define on which edge layers are not be generated and what modifications are allowed on an edge if a neighboring edge has layers. You have to select a line on which layers are to be grown and a parent surface which indicates which side of the edge layers need to be created. These are also optional mesh controls and should be utilized if specific treatment is needed on without layer edges other than default.
Entity Selection Parameters
In the Entities field, use the entity selector to select the entities that the mesh control applies to.
The following entities can be selected using the entity selector:
- Lines / Lines regions
- Parent surfaces / Parent surface region
Meshing will only work if surfaces have mesh associated with them.
Edge Layer Parameters
| Parameter | Description |
|---|---|
| Line node seeding |
|