Setting Analysis Duration and Initial Gas Composition

The simulation starts at 300 deg CA and runs until 800 deg CA. To set the initial gas composition in the cylinder and ports, you use Automatic Composition Initialization.

Automatic Composition Initialization automatically determines the initial gas composition in the intake port, the exhaust port, and the cylinder based on the fuel-air mixture and the exhaust gas recirculation (EGR) composition. For information on the calculation of the initial mass fractions for the chemical species, see Automatic Composition Initialization.

The calculated initial mass fractions in the intake port and the exhaust port are also set as boundary conditions at the inlet and the outlet, respectively.

To set the duration of the analysis:
  1. Right-click the Operating Conditions node and select Edit.
  2. In the Operating Conditions group box, set Duration to 500.0 degCA.
To automatically initialize the gas composition:
  1. Make sure that Automatic Composition Initialization is activated.
    The default settings assume that the simulation starts during the exhaust stroke. In that case, the cylinder and the exhaust port contain only exhaust products and the intake port contains pure air. The EGR for the intake port and thereby the intake boundary is set to 0.0, which means that no exhaust gas enters the engine through the inlet due to recirculation.
  2. Click Apply, then Close.
  3. Save the simulation .