Initialization

Initialization

The Initialization view sets the initial conditions (velocity, pressure, temperature and turbulence) for the cylinder, intake and exhaust ports. For more details on this process see Chapter 8, “Initialization” in the User Guide.

Cylinder

To check that the correct cells are included in the Cylinder domain:

•Check that Cylinder is selected from the domain drop-down menu (see Figure 6-10)

•Click Define to check that es-ice has the correct cell type definitions. This displays the cells and opens the Cell Type Tool (see Figure 6-8)

•If this domain contains cells of the correct type, continue specifying their initial flow variable values. If not, use the Cell Type Tool to add and/or remove cell types until the correct ones are selected. Clicking Define in the Cell Type Tool to confirm any changes you have made.

Figure 6-8 Cell types for Cylinder 1

For initial conditions, you can specify a constant initial value or use a value from a table. In this tutorial, you will use a table stored in an external file. When using a table, initial pressure and temperature for the selected domain is based on the initial crank angle at the beginning of the STAR calculation. For example, Cylinder-3600.dat contains cylinder pressure and temperature as a function of crank angle, as shown in Figure 6-9.

CA P(Bar) T(K)

Figure 6-9 Contents of cylinder-3600.dat

To set the initial conditions for the Cylinder domain:

•Set Absolute pressure to Table in file from the drop-down menu

•Click the ellipsis (...) next to Table in file and select cylinder-3600.dat via the file browser

•Click Save to store the data as an es-ice image

•Ensure that the value next to the ellipsis for pressure is set to 2. This identifies the table’s second column as the repository for pressures

•Set the units to bar from the drop-down menu

•Set Temperature to Table in image from the drop-down menu

•Click the ellipsis (...) and select cylinder-3600.dat via the file browser

•Set the value next to the ellipsis for temperature to 3. This identifies the table’s third column as the repository for temperatures

•Check that the units are set to K from the drop-down menu

Figure 6-10 Star Controls panel: Initialization view of Cylinder

Port 1 and Port 2

To set the initial conditions for Port 1 and Port 2:

•Repeat the previous steps for each port, using intake-3600.dat for Port 1 and exhaust-3600.dat for Port 2 (see Figure 6-11 and Figure 6-12)

•For Port 1, check that Valve function is set to Intake

•For Port 2, set the Valve function to Exhaust

Figure 6-11 Star Controls panel: Initialization view of Port 1

Figure 6-12 Star Controls panel: Initialization view of Port 2