Setting the Duration of the Analysis and the Time-Step Size

The simulation starts at 300 deg crank angle and runs until 600 deg crank angle. For the automatic time-step control, you adjust the time periods before and after fuel injection. Additionally, you reduce the time-step size that is used during fuel injection.

For a motored-test simulation as described in the Gasoline Engine tutorial, Simcenter STAR-CCM+ In-cylinder runs 10 inner iterations per time-step. For a charge-motion simulation, Simcenter STAR-CCM+ In-cylinder increases the number of inner iterations to 20 to improve convergence and mass conservation. However, the increased number of inner iteration increases the runtime of the simulation. To reduce the runtime of this tutorial, you decrease the duration of the analysis from 420 deg crank angle to 300 deg crank angle.

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 300.0 degCA.
  3. Click Apply, then Close.
To adjust the time periods for the automatic time-step control:
  1. Right-click the Solvers node and select Edit.
  2. In the Time-Step Settings group box, click Settings.
  3. In the Auto Time-Step Settings dialog, click the Injectors tab and set the following properties:
    Period Time Step
    Before Injection 1.0 degCA 1.0E-6 (default value)
    During Injection 7.5E-7
    After Injection 20.0 degCA 5.0E-6 (default value)
  4. Click OK.
  5. Click Close.
  6. Save the simulation .