Generating the Volume Mesh

After assigning parts to regions, you can define the mesh settings for the simulation to generate a polyhedral volume mesh. For this simulation, the polyhedral mesher is used in conjunction with the advancing layer mesher to build a mesh suitable for predicting the swirling flow inside the cyclone.

In this simulation, in order to resolve the swirling motion of the fluid, you apply a volumetric mesh refinement through the middle of the cyclone. You also apply refinement on the inlet.

To set up and generate the volume mesh:
  1. Right-click the Geometry > Operations node and select New > Mesh > Automated Mesh.
  2. In the Create Automated Mesh Operation dialog:
    1. Select Main Body and Outlet Pipe from the Parts list.
    2. Select the following meshers, in order:
      Group Mesher
      Surface Meshers Surface Remesher
      Core Volume Meshers Polyhedral Mesher
      Optional Boundary Layer Meshers Advancing Layer Mesher
    3. Click OK.
    An automated mesh operation is added to the Operations node.
  3. Edit the Automated Mesh > Default Controls node and set the following properties:
    Node Property Setting
    Base Size Value 0.0125 m
    Target Surface Size Percentage of Base 80.0
    Minimum Surface Size Percentage of Base 30.0
    Surface Curvature # Pts/circle 72
    Surface Growth Rate User Specified 1.3
    Number of Prism Layers Number of Prism Layers 5
    Prism Layer Stretching Prism Layer Stretching 1.2
    Prism Layer Total Thickness Size Type Absolute
    Absolute Size 0.012 m
    Volume Growth Rate Volume Growth Rate 1.1
Two shape parts are used in separate volumetric control operations to refine the mesh. The mesh refinement in the middle of the geometry and around the inlet are created to capture the turbulent behavior of the flow accurately.
  1. For the core refinement in the middle of the cylinder, create a cylinder shape part:
    1. Right-click the Geometry > Parts node and select New Shape Part > Cylinder .
    2. In the Create/Edit Cylinder Part dialog, set the following properties:
      Start Coordinate End Coordinate Cylinder Radius
      X 0.0 m 0.0 m 0.03 m
      Y 0.0 m 0.0 m
      Z -0.3 m 0.9 m
    3. Click OK.
  2. For refining the mesh around the inlet, create a block shape part:
    1. Right-click the Geometry > Parts node and select New Shape Part > Block
    2. In the Create/Edit Block Part dialog, enter the following values for the block:
      Property Setting
      Corner 1 [-0.21, -0.11, -0.01] m
      Corner 2 [0.023, -0.055, 0.11] m
    3. Click OK.
Volumetric controls allow you to set custom mesh conditions for any geometry that falls within the volume covered by the control. Each control requires a part specification that defines the volume.
  1. To create the core mesh refinement:
    1. Right-click the Geometry > Operations > Automated Mesh > Custom Controls node and select New > Volumetric Control.
    2. Rename Volumetric Control to Cylinder Refinement.
    3. Edit the Custom Controls > Cylinder Refinement node and set the following properties:
      Node Property Setting
      Cylinder Refinement Parts Cylinder
      Controls
      Surface Remesher Customize Size Activated
      Polyhedral Mesher Customize Polyhedral Mesher Activated
      Values
      Custom Size Percentage of Base 50.0
  2. To create the inlet refinement:
    1. Right-click the Custom Controls node and select New > Volumetric Control.
    2. Rename Volumetric Control to Inlet Refinement.
    3. Edit the Custom Controls > Inlet Refinement node and set the following properties:
      Node Property Setting
      Inlet Refinement Parts Block
      Controls
      Surface Remesher Customize Size Activated
      Advancing Layer Mesher Customize Total Thickness Activated
      Polyhedral Mesher Customize Polyhedral Mesher Activated
      Values
      Custom Size Percentage of Base 50.0
      Custom Prism Values > Prism Layer Total Thickness Size Type Absolute
      Absolute Size 0.008 m
Now that all mesh settings are defined, you can generate the volume mesh.
  1. Click (Generate Volume Mesh) in the toolbar or select Generate Volume Mesh in the Mesh menu.

    The run and progress of the meshers are displayed in the Output window.

  2. To display the volume mesh, from the Vis toolbar, click (Create/Open Scenes) and select Mesh.
    The volume mesh is displayed below.