Building the Mesh

This section describes the step-by-step procedure for preparing the mesh for the radial piston pump. The Rotor Template Mesher is used to create the piston-cylinder assembly mesh and the General Mesher is used to create the mesh for the inlet, outlet and the valve plate.

Inlet and Outlet Meshes

Select General Mesher in the Mesh Panel.
Select CAD Surfaces inlet_inlet, inlet_mgi_VP, inlet_walls, outlet_mgi_VP, outlet_outlet, outlet_walls in the Geometric Entities Panel and click Add Surfaces icon for CAD Surfaces in the Properties Panel.
Enter Maximum Cell Size as 0.01, Minimum Cell Size as 0.001 and Cell Size on Surfaces as 0.005 in the Properties Panel.
Click Create Mesh. A new mesh mesh is created under Built Meshes in the Geometric Entities Panel.
The meshed volumes inlet and outlet are generated under Volumes.

Figure 6.378 - Inlet and Outlet mesh settings

Valve plate Mesh

Select General Mesher in the Mesh Panel.
Select CAD Surfaces VP_mgi_inlet, VP_mgi_outlet, VP_piston, VP_walls in the Geometric Entities Panel and click Add Surfaces icon for CAD Surfaces in the Properties Panel.
Enter Maximum Cell Size as 0.005, Minimum Cell Size as 0.001 and Cell Size on Surfaces as 0.0025 in the Properties Panel.
Click Create Mesh. A new mesh VP is created under Built Meshes in the Geometric Entities Panel.
The meshed volumes VP_1 and VP are generated under Volumes.
Select Split/Combine Geometry or Grid in the Mesh Panel.
Select the Volumes VP_1 and VP. Select Combine from the Operation drop-down list in the Properties Panel, click Combine and rename as valve_plate.
Select the Boundaries as shown in Table 6.15. Select Combine from the Operation drop-down list in the Properties Panel.
Click Combine and rename with corresponding names as shown in Table 6.15.

Figure 6.379 - Valve plate mesh settings

Boundaries	Rename as
VP_walls, VP_walls_1	VP_walls
VP_mgi_piston, VP_mgi_piston_1	VP_mgi_pistons

Table 6.15 - Connect and rename boundaries

´	Note: Two connected Volumes, such as the inlet and valve_plate, valve_plate and outlet can not be meshed together using the General Mesher.

Radial Piston - cylinder assembly Mesh

Select Rotor Template Mesher in the Mesh Panel.
Select Radial Piston from Rotor Type drop-down list in the Properties Panel.
Select CAD Surfaces piston_wall in the Geometric Entities Panel, click Add Surfaces icon for Piston Wall in the Properties Panel. Similarly select the CAD Surfaces piston_cylinder, click Add Surfaces icon for Cylinder Wall.
Select CAD Surface piston_cap and piston_mgi_VP, click Add Surfaces icon for Cylinder Cap. Similarly select CAD Surfaces cam, click Add Surfaces icon for Piston Cam.
Enter the parameters as follows.
- Number of Pistons: 9
- Rotational Axis Vector: 0, 0, 1
- Center of Rotation: 0, 0, 0
- Maximum Cell Size: 0.01
- Minimum Cell Size: 0.001
- Cell Size on Surfaces: 0.005
Click Build Radial Piston Mesh. The new mesh radial is created under Built Meshes in the Geometric Entities Panel.
The meshed volume radial is generated under Volumes.

Figure 6.380 - Radial piston - cylinder mesh settings

Note: The imported geometry does not include any leakage gap by default. The parameters for the gaps can be adjusted by selecting a Advanced Mode under Setup Options in the Properties Panel.

Figure 6.381 - Inlet and Outlet mesh

Figure 6.382 - Valve plate mesh

Figure 6.383 - Piston-cylinder assembly mesh

Create interfaces

In this section, the Mismatched Grid Interfaces (MGIs) are generated between boundaries.

The steps to create the MGIs are shown below:

Geometric Entities Panel > Volumes > Boundaries, select Boundaries as shown in Table 6.16.
Click Connect Selected Boundaries via MGI icon to create the MGI entities (see, Figure 6.384).

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

Connecting interfaces	Boundaries	Entity
Inlet and valve plate	inlet_mgi_VP, VP_mgi_inlet	MGI01
Outlet and valve plate	outlet_mgi_VP, VP_mgi_outlet	MGI02
Pistons and valve plate	piston_mgi_VP, VP_mgi_piston	MGI03

Table 6.16 - Creating interfaces

The new entities are created under MGI in Volumes (see, Figure 6.385).

Figure 6.384 - Connecting Inlet and Valve plate

Figure 6.385 - Created interfaces

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