Mesh Sizing In Ansys Workbench

Before we get started with the basics of mesh sizing in the Ansys workbench, let’s explore meshing in brief.

What is Meshing?

One of the most crucial processes in carrying out an accurate simulation using FEA is meshing. A mesh is composed of elements that have nodes—coordinate positions in space that might change depending on the element type—that symbolise the geometry's shape. Uneven forms are difficult for an FEA solver to work with, but typical shapes like cubes make it much happier. Meshing is the process of transforming amorphous shapes into "elements," which are more discernible volumes. Before starting with meshing, you would need to feed the CAD model/design into a simulation software like Ansys.

Meshing in Ansys

As meshing is a process that demands a great deal of accuracy, it is important to work with sophisticated software like Ansys. Obtaining simulation results often take a long time, therefore, Ansys Meshing has developed sophisticated automated mesh creation systems that can offer CFD & FEA Meshing solutions that are quicker and more accurate.

Working with the Mesh Module

• The First step in Working with the Mesh module is to open the module by selecting the type of solver or the component from the toolbox. 
• After Importing (the solver on the project schematic page), We can access the Mechanical module by double clicking on the Model. 

• Once the Mechanical module is open, the mesh settings can be accessed by clicking on the mesh from the project tree or by right-clicking on the mesh for applying the necessary settings.

Sizing for Various Types of Local Mesh Controls

The sizing can be inserted by right-clicking on the Mesh→Insert→Sizing. Whenever the user wants to improve or just change the element size for a specific model or a part of a model instead of trying to change the mesh for the whole body, Mesh sizing is used.

The Mesh Sizing can be used to set the following:

• The element size for a selected body, face, or edge.
• The number of divisions along an edge
• The scale factor for a selected body, face, or edge

The Scoping method, the geometry selection and the suppressed definition are the same in terms of use as discussed in the earlier article in Inserting the Method.

Definition

A. Type

The type of sizing decides the way in which the elements are sized with respect to the various selection methods. The various types are discussed below.

• Element size: Irrespective of the type of selection of the geometry for element size, there is always a default element size available options in the type field. The values entered must be positive in nature (Decimal points element sizes are accepted). By typing in the element size as ‘Zero’ in the type field, the mesher will show the default value of the mesh.
  
• Sphere of Influence: The Sphere of Influence alternative is accessible in the ‘Type’ field after you select part of the geometry, for instance, a body, face, edge, or vertex. The sphere of influence can be used when a portion of geometry needs to mesh refinement. In the event that the Sphere of Influence is scoped (selected) to a body or vertex, the Sphere of Influence affects the entire body regardless of the sizing options being used. In the event that the Sphere of Influence is scoped to a face or edge and ‘Use Adaptive Sizing’ is set to ‘Yes’, the Sphere of Influence only affects the face(s) or edge(s) that are scoped to the control and the transition away from those entities. If the Sphere of Influence is scoped to a face or edge and any other sizing option is used, the Sphere of Influence will affect the whole body.

• Body of Influence: The Body of Influence is accessible in the Type field if you choose a body and ‘Use Adaptive Sizing’ is set to ‘No’. Utilizing this, one can set the source as another body (that is, a Body of Influence). The Body of Influence will impact the Mesh Density of the body that it is scoped to, but it won't be a part of the model geometry nor will it be Meshed. Body of Influence bodies is noted in the Details View of each prototype that is used. An example is shown below.

• The factor of Global Size: The factor of Global size is one of the options available in the type field when ‘Use Adaptive Sizing’ is switched to ‘No’. The Factor of Global Size can be selected to enter a value for Element Size Factor to define the local minimum and defeature sizes as factors of the global element size. When the local sizings are defined as a factor of global size and when the element size is modified, the local sizings are recalculated.

• Number of Divisions: The Number of Meshing can be used for all Meshing algorithms except for Assembly Meshing Algorithm. The Number of the divisions type field is available when an edge of the model is selected for sizing. Choosing the Number of Divisions and entering a value in the Number of Divisions field is an alternative for Element Size if there is a necessity for the mesh to be sized according to a discrete number of divisions along an edge.
  
  

Advanced

• Defeature Size: For body-sizing and face-sizing controls, the defeature size sets the local tolerance for defeaturing. The Features smaller than or equal to the tolerance given will be removed when the mesh is being generated. The defeature size can be any non-negative value provided according to the need of the user. If the local sizing is Uniform, the default local Defeature Size is set to the smaller of the following two values:

                                  A) Global Defeature Size

                                  B) 50% of the value of the local Element Size

• Behaviour: The behaviour can either be set as Soft (default) or Hard, but the effect depends on the type of mesh being generated. Setting the behaviour as ‘Hard’ results in a stricter size setting than ‘Soft’. For an instance, with a tri or tet mesh, the Hard setting would not allow as much transition from one element size to another element size due to influences of sizing on neighbouring objects.
  
  With a Hard setting, the element size defined would be maintained for the object to which the setting is scoped. With a Soft setting, the element size defined may be modified in order to respect other size settings in the vicinity of the object to which the setting is scoped.