Adjusting Battery Settings for the Distributed 3D Model

When necessary, Simcenter STAR-CCM+ automatically adjusts the battery cell model time-step to stabilize the circuit solver and obtain a solution.

For example, if a time-step of 100 seconds is specified in the Implicit Unsteady solver, the battery cell model normally delivers results in 100 seconds. However, if Simcenter STAR-CCM+ reduces the battery cell model time-step (for example, to 25 seconds), the battery model calls the unit cell model to deliver the results at 25-second increments.

You can specify what the unit cell model does in this scenario: attempt the full 25-second time-step, or use a specified maximum time-step. For example, if you specify a maximum time-step of 1 second (the default value), the unit cell model makes 25 substeps, each of 1 second, to reach the battery cell model time-step (25 seconds). This substepping usually enhances stabilization but requires a longer time to compute. However, if you specify a maximum time-step greater than 25 seconds, the unit cell model makes a single time-step of 25 seconds.

The larger maximum time-step setting allows the battery cell model to achieve the Implicit Unsteady time-step quickly. You can use this setting in cases where CFD calculations are not needed, such as conduction heat transfer problems or a single cell analysis with no cooling system. In these cases, change is slow and large time-steps can be taken without affecting the stability of the simulation.

To specify the maximum unit cell time-step:
  1. Under the [Battery Cell]Cell Properties node, expand the Models > IET > Distributed NP > Numerical Settings > Overall Battery Settings node.
  2. Select the Max Unit Cell Time-Step node and set the Value to the number of seconds for the maximum time-step value.