Building the Mesh

This section describes the step-by-step procedure for preparing the mesh for the scroll compressor. The Rotor Template Mesher is used for creating the scroll chamber mesh and the General Mesher is used for creating the mesh for the inlet, outlet and the scroll external volume.

Inlet Mesh

Select General Mesher in the Mesh Panel.
Select CAD Surfaces inlet_inlet, inlet_mgi_scroll, and inlet_wall in the Geometric Entities Panel and click Add Surfaces icon for CAD Surfaces in the Properties Panel.
Enter the Maximum Cell Size as 0.02, Minimum Cell Size as 0.001 and Cell Size on Surfaces as 0.01 .
Click Create Mesh. A new mesh inlet is created under Built Meshes in the Geometric Entities Panel.
To refine the interfaces, select inlet from Built Meshes and inlet_mgi_scroll from CAD Surfaces.
Select User Input from Cell Size on Boundaries drop-down list, enter 0.005 for Size in the Properties Panel. Click Create Mesh to update inlet mesh under Built Meshes in the Geometric Entities Panel.
The meshed volumes inlet is generated under Volumes.

Figure 6.811 - Inlet mesh settings

Scroll Chamber Mesh

Select Rotor Template Mesher in the Mesh Panel.
Select Scroll from the Rotor Type drop-down list.
Select CAD Surfaces scroll_stator in the Geometric Entities Panel, click Add Surfaces icon for Stator in the Properties Panel. Similarly select CAD Surfaces scroll_rotor and click Add Surfaces icon for Rotor.
Select CAD Surfaces scroll_stator_end and click Add Surfaces icon for Stator End.
Enter the parameters as follows.
- Rotational Axis Vector: 0, 0, 1
- Stator Center: 0, 0, 0
- Rotor Center: -0.0016505829, 0.0014955489, 0
Click Build Scroll Mesh. The new mesh scroll is created under Built Meshes in the Geometric Entities Panel.
The meshed volumes scroll is generated under Volumes.

Figure 6.812 - Scroll chamber mesh settings

Outlet Mesh

Select General Mesher in the Mesh Panel.
Select CAD Surfaces outlet_mgi_scroll, outlet_outlet and outlet_wall in the Geometric Entities Panel, click Add Surfaces icon for CAD Surfaces in the Properties Panel.
Enter the Maximum Cell Size as 0.005, Minimum Cell Size as 0.0001 and Cell Size on Surfaces as 0.0025 .
Click Create Mesh. A new mesh outlet is created under Built Meshes in the Geometric Entities Panel.
The meshed volumes outlet is generated under Volumes.

Figure 6.813 - Outlet mesh settings

Scroll External Volume Mesh

Select General Mesher in the Mesh Panel.
Select CAD Surfaces scrollex_mgi_inlet, scrollex_mgi_scroll, scrollex_mgi_scroll_end and scrollex_wall in the Geometric Entities Panel, click Add Surfaces icon for CAD Surfaces in the Properties Panel.
Enter the Maximum Cell Size as 0.01, Minimum Cell Size as 0.0008 and Cell Size on Surfaces as 0.005 .
Click Create Mesh. A new mesh scrollex is created under Built Meshes in the Geometric Entities Panel.
The meshed volumes scrollex is generated under Volumes.

Figure 6.814 - Scrollex mesh settings

´	Note: The mesh can be edited/replaced by selecting it under Built Meshes, and modify the mesh parameters in the Properties Panel. Click Create Mesh to reflect the changes.

The mesh created for the fluid domain is shown below.

Figure 6.815 - Inlet, Outlet and Scroll external volume mesh

Figure 6.816 - Scroll mesh

Create interfaces

In this section, the MGIs are generated between boundaries. It connect the various volume surfaces to the appropriate adjacent volume surfaces

The steps to create the MGIs are shown below:

Geometric Entities Panel > Volumes > Boundaries, select Boundaries as shown in Table 6.42.
Click Connect Selected Boundaries via MGI icon to create the MGI entities (see, Figure 6.817).

A group display of entities can be viewed using the Group Entities by Volumes/Types icon inGeometric Entities Panel toolbar.

Connecting interfaces	Boundaries	Entity
Scroll external and scroll	Scrollex_mgi_scroll_end and stator_end	MGI01
Scroll and scroll external	scroll_stator and scrollex_mgi_scroll	MGI02
Inlet, scroll and scroll external	Inlet_mgi_scroll, mgi_ports_2 and scrollex_mgi_inlet	MGI03
Scroll and outlet	Mgi_port_1 and outlet_mgi_scroll	MGI04

Table 6.42 - Creating interfaces

An entity MGI02 is created but the Interface was not created because the default parameters associated the MGI02 were too restrictive to find the connection. These parameters can be relaxed to enable the MGI logic to create the correct fluid-fluid connection.

The steps to create the Interface for MGI02 are shown below:

Select MGI02 under Geometric Entities Panel.
Enter the following parameters under Properties Panel > Model Tab:
- Projection Tolerance: 0.1
- Normal Tolerance: 89
- Face Normal Tolerance: 5
- Face Distance Tolerance: 0.0001

With the specified tolerances, the MGI02 interface is successfully created. For more details on projection tolerance refer manual.

The new entities are created under MGI > Volumes (see, Figure 6.818).

Figure 6.817 - Scroll external and scroll

Figure 6.818 - Created interfaces

Note: If MGIs are created by connecting the wrong boundaries, delete the created MGIs by clicking on Delete Selected Geometric Entity icon and then recreate the MGIs.