Simcenter STAR-CCM+ How many inner iterations did my time step use?

2024-02-08T15:23:52.000-0500
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Summary

In this article you will find an answer for the question how to monitor and plot number of inner iteration during transient run with advanced/intelligent stopping criteria in Simcenter STAR-CCM+.

Details

When running a transient simulation, it is often beneficial to use stopping criteria based on one or several physical quantities, such as maximum pressure or volume average velocity. Just using a fixed number of steps will likely lead to either using too many inner iterations or non-convergence within a time step.

In this example, we will advance in timestep when stopping criteria from point 1. or 2. (below) are fulfilled:
  1. Continuity Criterion AND Minimum Inner Iterations AND Volume Average Velocity Monitor Criterion,
  2. Maximum Inner Iterations.
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Quite the strong stopping criteria!

Looking at the residuals we can see that the simulation seems to use about 10-40 iterations/timestep.
 
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You can of course manually check how many iterations were used at each timestep but how do we plot this?

We will need to create:
  1. A new Expression Report of: ${Iteration}, with a monitor triggered at each timestep,
  2. A new Statistics Report of the Monitor from point 1 that will sum up the iterations from this and the previous timestep (Last N Samples = 2),
  3. A new Expression Report of: 2*report from point 1 minus report from point 2,
  4. Create Monitor and Plot of report from point 3.
 
The fastest way however, would be to just download and run the attached java-macro. For reference see attached .sim file as well.
 
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KB Article ID# KB000042064_EN_US

Contents

SummaryDetails

Associated Components

Design Manager Electronics Cooling In-Cylinder (STAR-ICE) Job Manager Simcenter STAR-CCM+