The Mesh Setup tool allows you to change the meshing settings. It's found under the Mesh tab in the Mesh settings group. It opens a tab in the same Group List Window with various categories.
Meshing Parameters
Global Parameters
A global parameter is used whenever that parameter is not set on an node, edge, or face.
Max size
Ennova will try to limit the largest element size to the max_size .
Min size
Ennova will try to make sure no element is smaler than the min_size .
Sag number
When a curved geometry is approximated by a piecewise linear element, the middle of the element may be a small distance from the curved geometry. Call this distance d (the deviation). The sag number is the ratio of the deviation to the size of the element. It is a unitless quantity. When you specify a sag number, Ennova will attempt to refine the mesh until the sag number is lower than the specified value. Ennova will not refine the mesh lower than the min_size. The min_size needs to be set to a value greater than zero for the sag number to have an effect.
Refinement number
The refinement number is another way of looking at the sag number. It is the number of elements that need to be used to represent a circle. If the refinement number is set to 8, then a circle will be represented as an octagon. The sag number and the refinement number are related by a simple formula, so you cannot set the separately.
Size Ratio
The size ratio controls how quicky element sizes grow as you move away from a size constraint. If the size ratio is 2 then the next element away from a size constraint can be twice as large, and the next twice as large as that. At a distance d away from a size contraint c, the size can be s = c + (r - 1)*d where r is the size ratio.
Run Booster
If this box is checked, then after running the volume mesher, Ennova will run a booster program to improve the quality of the volume elements. This can take some time, so if you are experimenting with sizes/spacing and other surface meshing issues you don't need to have this turned on. Turn it on when you are going to generate your final volume mesh for the solver.
Optimize for
Different solvers have different meshing requirements and preferences. If Ennova knows which solver you are going to use, it can make intelligent decisions during meshing.
Elements in gap
You can control how many elements Ennova will place in a gap between two surfaces with this control. This will affect both the surface mesh and the volume mesh. The elements will not be refined smaller than min_size to satisfy this request. The min size must be specified for this control to have an effect.
Search Floor
If you are using Elements in gap, Ennova will not refine in gaps that are smaller than search floor.
All Triangles
Ennova can identify surfaces are being good candidates for structured meshing. If you choose all triangles, the Ennova will not use a structured mesh on any face.
Topological Mesh Parameters
Ennova has several ways to generate a mesh. One of them is to use the topology of the geometry as a guideline. In this approach, the geometry must be water tight to generate a volume mesh. Each geometric corner gets a node. Each edge will be meshed with a series of nodes. Each face then gathers the nodes of its edges and generates a surface mesh on that face. Finally, each volume collects the surface meshes from all of the faces to create a closed boundary from which to make a volume mesh. This approach places the most restrictions on the geometry, but produces a high quality mesh quickly. The following group of meshing parameters are only used in this approach.
Scale Factor
If you specify a number > 1 then the element size will be that factor times the size requested by all of the other meshing parameters A scale factor > 1 will generate a coarser mesh. A scale factor < 1 will generate a finer mesh.
Expansion factor
This is a duplicate of Size Ratio and is being phased out.
Surface Mesh Only
With the topology meshing option, the meshing can be halted at various stages. With "Surface Mesh Only" the topology mesher will stop after creating the surface mesh. You can proceed to add prism layers or tet elements at a later time. With "Surface + Volume Mesh (NO prisms)", the topology mesher will not generate the prism layer even if you asked for it elsewhere. "Surface + Volume Mesh (w/ Prisms)" will generate everything including prisms if you have specified them.
Max Aspect Ratio
On some highly curved surfaces, such as the leading edges of wings or in pipes, it can be economical to generate a structured surface mesh with high aspect ratio quads. The short sides of the quad will go in the direction of high curvature and the long sides will go in the direction of low curvature. This kind of anisotropic meshing can yeild better solver results with fewer elements. A larger value allows more stretched elements.
Shrink Wrap Parameters
A second way the Ennova can generate a surface mesh is using the shrinkwrap method. In this method, not every geometry entity will have something representing it. This method can be used even if the geometry is not watertight. This method can generate a mesh that is coarser than the topology of the geometry. You could, in theory, mesh an entire car with a single cube.
This method starts with a background cartesian volume mesh and refines it according to the mesh sizing controls you have specified. After that, it rounds nodes onto the surface and splits edges at the surface. Finally it chooses faces from the background volume mesh to represent the geometry.
Which Coordinate
With this option you can choose a local coordinate system to orient the background mesh. This is currently not working
Gap Close Tolerance
With the Shrink Wrap Mesher the geometry doesn't need to be topologically or even geometrically closed. To create a closed volume from a geometry that has holes, use the gap close tolerance. If you set the tolerance to t than every hole in the geometry smaller than t will automatically be closed
Gap Close Refinement
If the Gap close refinement is set to a number > 1, then after closing the holes in the model, the mesher will refine those elements. So if the gap close refinement is set to 4 then those elements will be made 1/4 the size.
Scale Down Factor
If the scale down factor is set to a number < 1 and > 0 then the mesh produced by the shrinkwrapper will have smaller elements according to the factor. So a scale down factor of .5 will make a mesh with elements 1/2 the size and about 4 times the number of elements.
Gap Elements to New Group
If this is checked, then the elements created to fill holes will be put into the group "zz_gap_close", otherwise they will be put into the group of a nearby surface.
Which Volume
The shrinkwrap mesher will output the shell elements that form the boundary of a specified volume. That can be the outside of all geometry "External", the boundary of the largest enclosed volume, "Largest Internal", or the boundary of the second and so on. You can also specify the volume by using a see point.
Keep Internal Shells
Your model might also have faces/surfaces that are contained within the desired volume but are not part of the boundary. An example might be a baffle surface, or a piece of sheet metal with fluid/air on either side. If this checkbutton is off then not shell elements will represent these surfaces. With the checkbutton turned on these surfaces will be represented by shell elements.
Wrap Post Processor
After the shrinkwrap mesher is run a wrapper post process is run. This will remote any "floating" groups of elements.
Delete Isolated Volume
With this box checked the wrapper post processor will find unattached groups of few elements and delete them.
Max number of elements
Here you can specify the maximum number of elements that any isolated group can have and be deleted.
Boundary Layer
After generating the surface mesh, either using the topology mesher or the shrinkwrapper, you can generate a boundary layer.
Volume Prism Layer Default
With this set, the default is that a volume will have a boundary layer generated.
# Prism Layers
This spin box controls the default number of layers that will be generated off of a face. If a value is specified on the group of a face, that value will have precedence
Height
This controls the default initial prism height. If a value is specified on the group of a face, that value will have precedence
Height Ratio
This controls the ratio of the height of the second layer of prisms to the first and the height of the 3rd to the 2nd and so on. If a value is specified on the group of a face, that value will have precedence
Stair Step
If a certain prism cannot be grow because it would run into interference with some other piece of geometry the prism mesher can stop growing that column or it can shrink the element height so that call prisms can be grown. The option is currently ignored
Auto Reduction
If a certain prism cannot be grow because it would run into interference with some other piece of geometry the prism mesher can stop growing that column or it can shrink the element height so that call prisms can be grown. If the "Auto Reduction" box is checked the element heights will be reduced.
Minimum Quality
If the quality of some extruded elements falls below this threshold, then the elements will not be generated in that neighborhood.
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