22.5. Dynamic Model Control Tab

Dynamic Model Control

Selecting Global Dynamic Model Control enables some special modes to be implemented in the solver for the first few iterations or timesteps. For details, see Dynamic Model Control in the CFX-Solver Modeling Guide.

For details on Turbulence Control, see Turbulence Control in the CFX-Solver Modeling Guide.

For details on Combustion Control, see Advanced Combustion Controls in the CFX-Solver Modeling Guide.

For details on Hydro Control, see Hydro Control in the CFX-Solver Modeling Guide.

For details on Harmonic Balance Control, see Harmonic Balance Control in the CFX-Solver Theory Guide.

Dynamic Variables

These settings enable you to activate, and define the behavior of, any existing Dynamic Additional Variables. If not activated, a Dynamic Additional Variable defaults to a value of unity and therefore does not affect the simulation.

Note:  A Dynamic Additional Variable, or simply Dynamic Variable, is an Additional Variable that has Variable Type set to Dynamic Variable. For details, see Basic Settings Tab for Additional Variable Objects.

Select a Dynamic Variable in the list, then select the check box of the same name to define the control steps for that variable.

Set Option to one of the following:

  • Uniform Scale, Exponential Scale, Signmodial Scale

    Set Num. Control Steps to the number of control steps that must be completed before the value switches to unity.

    Set Initial Value to a positive value; this value can be less than, or greater than, unity.

    The Dynamic Variable will begin at the specified initial value and proceed toward unity using the set number of control steps and with a variation between control steps in accordance with the type of scale implied by Option.

  • Value List

    Set Values to a comma-separated list of non-dimensional values.

    The Dynamic Variable will proceed through the list of specified values before the value switches to unity. Note that the number of control steps is implied by the length of the list.

    Select Save Intermediate Files to save files at the successful completion of a control step. These files could be used to restart the simulation if needed.

    Select Smooth Step Transitions to allow a Dynamic Variable to move steadily towards its next value, rather than apply a step change at the end of a control step. The specified value for any given control step is achieved by ramping linearly over the specified minimum number of iterations, starting from the previous control step's final value.

    Set the Convergence Control and Convergence Criteria settings to indicate the conditions required for completion of a control step for the applicable Dynamic Variable. Note that these convergence settings, which affect only the applicable Dynamic Variable, should be compatible with the convergence settings on the Basic Settings tab of the Solver Control details view, which control the overall simulation.

    When Save Intermediate Files is selected, the Backup Data Retention setting are available. To use these settings, select Backup Data Retention, then set Option to one of the following:

    • Delete Old Files

      Causes all intermediate files for the applicable Dynamic Variable to be deleted as soon as newer files are saved.

    • Keep All Files

      Retains all intermediate files saved during the run.

After all control steps are complete, the Dynamic Additional Variable assumes a value of unity for the rest of the convergence process.

For modeling information, see Dynamic Additional Variables in the CFX-Solver Modeling Guide.