Chapter 6	STAR SET-UP IN ES-ICE
	Boundary Conditions

Boundary Conditions

The Boundary conditions view sets the boundary type and boundary conditions for the cylinder, intake and exhaust ports, and intake and exhaust valves. As with initial conditions, boundaries for each domain are defined separately. For more details on Boundary Conditions see Chapter 8, “Boundary Conditions” in the User Guide.

Cylinder

The relevant boundaries for the Cylinder are Piston crown, Cylinder wall, Combustion dome and Symmetry plane. For each boundary, you can specify a Fixed or Mapped temperature or an Adiabatic condition. In addition, you can specify different temperatures at different heights of the Cylinder wall by using the Zone boundary type.

In this tutorial, you will specify Fixed temperatures at all cylinder boundaries.

•Click Boundary conditions on the left of the Star Controls panel (see Figure 6-14)

•Check that Cylinder is selected from the domain drop-down menu

•Set Combustion dome regions to Fixed from the drop-down menu

•Set Temperature to 450 K

•Set Piston crown regions to Fixed from the drop-down menu

•Set Temperature to 550 K

•Set Cylinder wall regions to Fixed from the drop-down menu

•Set Temperature to 500 K

In addition, set up an Extra region to define the spark plug.

•Select the Extra region toggle button

•Set Name to Spark Plug

•Click the Define button next to the Regions box

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

•Click Keep picked and pick the patches that define the spark plug in the Controls Workspace window, as shown in Figure 6-13:

Figure 6-13 Spark Plug patches

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Boundary Conditions

•Press q to exit from the pick mode

•In the Boundary Tool, click Define to define the generated patches as the

Extra region

•Select Fixed wall from the drop-down menu and set Temperature to 600 K

Figure 6-14 Star Controls panel: Boundary conditions view

Port and Valve 1

For Port and Valve 1, the relevant boundaries are Valve stem, Valve face and Port wall. For each boundary, you can specify a Fixed or Mapped temperature or an Adiabatic condition. In addition, you can specify an Extra region to define the intake flow boundary.

In this tutorial, you will specify Adiabatic conditions for all Port and Valve 1 boundaries.

•Select Port and Valve 1 from the domain drop-down menu

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

As the intake and exhaust manifolds are external meshes added during the Assembly process, es-ice assumes that all their boundaries are solid walls. Note that the Extra regions > Regions box is empty, which means that flow boundary conditions have not been assigned yet.

To define the intake flow boundary shells:

•Under Extra regions, set Name to Intake Flow Boundary

•Click the Define button next to the Regions box

•In the Boundary Tool, click Display all to show all Port 1 surface shells, as shown in Figure 6-15

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Chapter 6	STAR SET-UP IN ES-ICE
	Boundary Conditions

•Click Keep picked and pick the Intake Flow Boundary patch in the Controls Workspace window, as shown in Figure 6-15

Intake Flow Boundary

Figure 6-15 Redefining wall boundary condition for Port 1

•Press q to exit from the pick mode

•In the Boundary Tool, click Define to define the generated patch as the

Extra region

•Click Close tool to close the Boundary Tool panel

In this example, a value of 132 appears in the Regions box. This value represents the region ID for the intake boundary faces. Alternatively, if you know the region ID, you can manually enter its value into the box. In this case, you will also need to ensure that region ID 132 is removed from Port wall regions to avoid multiple boundary assignments. Note that if you use the Boundary Tool, es-ice automatically prevents multiple assignments.

To set the Intake Flow Boundary conditions shown in Figure 6-16:

•Set Absolute pressure to Environmental from the drop-down menu

•For Absolute pressure and Temperature values, follow similar steps to those for the Initialization process to import relevant data from the intake-3600.dat image file

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Boundary Conditions

Figure 6-16 Star Controls panel: Boundary conditions view of Port 1

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