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•Set the domain to Port 4 of Cylinder 1

•Check that Use data of is set to Port 1 of Cylinder 1 as it is an intake port

•Check that the remaining cylinder components are correct by referring to the following table:

Domain	Use data of
Cylinder of Cylinder 2	Cylinder of Cylinder 1
Port 1 of Cylinder 2	Port 1 of Cylinder 1
Port 2 of Cylinder 2	Port 2 of Cylinder 1
Port 3 of Cylinder 2	Port 2 of Cylinder 1
Port 4 of Cylinder 2	Port 1 of Cylinder 1

Boundary Conditions

In the Boundary conditions view of the Star controls panel, specify boundary conditions for all engine components.

For the cylinder component of Cylinder 1 (see Figure 14-20), set the following conditions:

•Select domain Cylinder of Cylinder 1 from the drop-down menus at the top

•Set the Combustion dome regions type to Fixed and the Temperature to 450 K

•Set the Piston crown regions type to Fixed and the Temperature to 550 K

•Set the Cylinder wall regions type to Fixed and the Temperature to 500 K

•Select the Extra regions toggle button to create a region for the spark plug

•Click Define to open the Boundary Tool

•In the Boundary Tool, click Display all to display all cylinder surface shells

•Click Keep picked to select the spark plug patches, as shown in Figure 14-19

Figure 14-19 Spark plug patches for Cylinder 1

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to define the patches as a spark plug

•Set the Name to Spark Plug

•Set the Regions type to Fixed wall

•Set the Temperature to 600 K

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Figure 14-20 Multiple cylinder Star Controls > Boundary conditions panel for Cylinder

For the Port and Valve 1 of Cylinder 1 (see Figure 14-22), specify the following conditions:

•Select domain Port and Valve 1 of Cylinder 1 from the drop-down menus

•Check that the Valve stem, Valve face and Port wall regions are set to

Adiabatic

•Under Extra regions, click Define to open the Boundary Tool

•In the Boundary Tool, click Display all to display all surface shells

•Click Keep picked to select the intake flow patch, as shown in Figure 14-21. The intake flow boundary region is split between Cylinder 1 and Cylinder 2, which is why it appears to be incomplete.

Intake flow patch

Figure 14-21 Intake flow boundary patch for Cylinder 1

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•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to define the displayed patch as the intake flow region

•Set the Name to Intake Flow

•Check that the Regions type is Pressure

•Set the Absolute pressure to Constant and Environmental using the drop-down menus

•Check that the Pressure is 101325 Pa (for atmospheric pressure)

•Check that the Temperature is 293.15 K (for atmospheric temperature)

Figure 14-22 Multiple cylinder Star Controls > Boundary conditions panel for Port 1

Since the relevant flow boundary patch belongs to Cylinder 2, it will be used here to define the boundary conditions (see Figure 14-24):

•Select domain Port and Valve 2 of Cylinder 2 from the drop-down menus

•Set Use data of to Port and Valve 2 of Cylinder 2 from the drop-down menus

•Under Extra regions, click Define to open the Boundary Tool

•Click Display all to display all surface shells

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•Click Keep picked to select the exhaust flow patch, as shown in Figure 14-23

Exhaust flow patch

Figure 14-23 Exhaust flow boundary patch

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to define the displayed patch as an exhaust

•Set the Name to Exhaust Flow

•Check that the Regions type is set to Pressure

•Set the Absolute pressure to Constant and Mean using the drop-down menus

•Check that the Pressure is 101325 Pa (for atmospheric pressure)

•Check that the Temperature is 293.15 K (for atmospheric temperature)

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Figure 14-24 Multiple cylinder Star Controls > Boundary conditions panel for Port 2

As with initialisation, the remaining ports and cylinders use the boundary conditions that were defined for their equivalent components, i.e. cylinder, intake or exhaust. However, for boundary conditions, you also need to define patches for the spark plug and the intake and exhaust boundary regions for Cylinder 2.

•Select domain Cylinder of Cylinder 2 from the drop-down menus

•Select the Extra regions toggle button and click Define

•Click Display all to display all surface shells

•Click Keep picked to select the spark plug patches, as shown in Figure 14-25

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to define the displayed patches as the spark plug

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Figure 14-25 Spark Plug patches for Cylinder 2

•Select domain Port and Valve 1 of Cylinder 2 from the drop-down menus

•Under Extra regions, click Define to open the Boundary Tool

•Click Display all to display all surface shells

•Click Keep picked to select the intake flow patch, as shown in Figure 14-26

•Press q on the keyboard to exit from the pick mode

•Click Define in the Boundary Tool to define the displayed patch as an intake

Intake flow patch

Figure 14-26 Intake flow boundary patch for Cylinder 2

•Select domain Port and Valve 2 of Cylinder 1 from the drop-down menus

•Set Use data of to Port and Valve 2 of Cylinder 2 from the drop-down menus

As there are numerous boundaries in this case, it is advantageous to use the

Summary feature to check that all boundary regions are correctly defined.

•Select Cylinder of Cylinder 1 and click the Summary toggle button to open the Summary view of Boundary conditions, as shown in Figure 14-27.

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