Defining Surfaces

Figure 2-7 Example of missing Features between the cylinder head and liner

Next, remove unnecessary Features from the surface geometry. You can use the diagnostics tool to highlights Features that, according to the software, are likely to need removing.

•In the surface repair panel, click Start Diagnostics... Feature errors are highlighted on the surface in cyan

•Clear the checkbox next to Reset Displayed to keep displaying the entire surface

•Use the Browse buttons to cycle through the

errors and inspect them individually

• Click Unflag feature edges (or press U on the keyboard) to remove a Feature

•When complete, click Close

Defining Surfaces

If no surface definitions were imported from the geometry, you can split the surfaces according to existing Features and then combine them to define the cylinder components.

•Expand the Geometry > Parts > Geometry > Surfaces manager, right-click the Surface node and select Split By Parts Curves...

•In the Split Part Surface by Part Curves panel, tick the part curve checkbox as shown in Figure 2-8

•Click Apply and then Close

Figure 2-8 Splitting surfaces by part-curves

Next, combine the surfaces to define the engine components, that is piston, liner, cylinder head, ports, valves and spark plug. The required surfaces can be selected on either the object tree or the Graphics window. To aid grouping of the remaining surfaces, hide the combined surfaces for each component. The following steps detail the process of combining surfaces representing the intake port (Port 1) with a table summarising the surfaces for other engine components.

To combine the surfaces:

•Expand the Geometry > Parts > Geometry > Surfaces manager. Select the following nodes while holding down the <Ctrl> key:

•Surface 9

•Surface 18

•Surface 26

•Surface 27

•Surface 31

•Surface 33

•Surface 35

•Surface 40

•Surface 42

•Right-click any of the

selected surfaces in the Graphics window and select Combine

•Right-click the combined surface, select Rename... and name the surface as

Port1

•Right-click the combined surface in the Graphics window and select Hide to allow an easier selection of the intake valve

•Follow the previously described steps to continue combining surfaces. For

your guidance, the surfaces for each engine component are summarised in the following table:

Remeshing and Exporting the Geometry

Typically, a valve surface mesh is of sufficiently high quality and thus more desirable than the remeshed surface. Therefore, the recommended practice is to separate the valves from the rest of the geometry.

•Press <Ctrl> key and select Geometry > Surfaces > Valve1 and Valve2

•Right-click one of the selected surfaces and select Create New Part From Surfaces (see Figure 2-9)

Figure 2-9 Creating a new part from the valve surfaces

•Rename Geometry > Parts > Part as Valves

The next step is to set up a Surface Remesher mesh operation and define its parameters:

•Right-click the Geometry > Operations node and select New > Automated

Mesh

•In the Create Automated Mesh Operation panel, tick the checkbox next to

Parts > Geometry

•Under Surface Meshers, select Surface Remesher and click OK

•Select the Automated Mesh > Meshers > Surface Remesher node

•In the Properties panel, set the Surface Remesher parameters as shown in Figure 2-10:

•Deselect the Perform proximity refinement checkbox

•Set Minimum face quality to 0.0

Figure 2-10 Surface Remesher properties

•Right-click the Operations > Automated Mesh > Default Controls node and select Edit...

•In the Edit panel, click Expand/Contract Tree to access all parameters

•Set the meshing parameters as shown in Figure 2-11:

•Set Base Size > Value to 1.0 m

•Ensure that the Project to CAD toggle button is selected

•Ensure Target Surface Size > Percentage of Base is set to 100

•Ensure Minimum Surface Size > Percentage of Base is set to 10

•Ensure that Basic Curvature > #Pts/circle is set to 36

•Set Surface Growth Rate to 1.5

•Click Close

Figure 2-11 Mesh reference values

The surface can now be meshed using the STAR-CCM+ Surface Remesher.

•In the Mesh Generation toolbar, click Generate Surface Mesh

•Right-click the Geometry > Parts > Geometry node and select Export

•In the Save panel, set Descriptions to Automated Mesh.Remesh from the drop-down menu

•Set File Name to geometryRemesh, Files of Type to pro-STAR Surface mesh (*.dbs) and click Save

•In the Database Export Options panel, set Database Id to 1, Title to

Geometry and click OK

•Right-click the Geometry > Parts > Valves node and select Export

•In the Save panel, ensure that Descriptions is set to Root from the drop-down menu

•Select geometryRemesh.dbs and click Save

•In the Database Export Options panel, set Database Id to 2, Title to Valves and click OK