Restoring the Premixed Eddy Break Up Model

The Premixed Eddy Break-Up model in Simcenter STAR-CCM+ v.11.04 behaves as a Partially Premixed version. You can restore the Premixed model settings as described in this section.

As part of a plan to improve and simplify the procedure for selecting combustion models, the Premixed version of the Eddy Break Up model is discontinued in Simcenter STAR-CCM+ v.11.04.

The new Eddy Break Up Model is an improvement on the deprecated Premixed Eddy Break Up Model—the new Eddy Break Up model:
  • Supports multiple reactions as well as hybrid and kinetics-based schemes. Therefore, you can perform calculations more accurately and over wider operation ranges.
  • Accounts for oxidizer and product concentrations when calculating the source term.
  • Allows you to switch between fully premixed and partially premixed calculations.
When loading a simulation in Simcenter STAR-CCM+ v.11.04 or later that was saved in a version of Simcenter STAR-CCM+ before v11.04, the Premixed Eddy Break Up model behaves as a Partially-Premixed Eddy Break Up model. Several settings are defined differently and must be set up again. The following images show a comparison of the temperatures on the cross section of a flame holder.
PEBU 11.02 PEBU 11.04 (Partially Pre-Mixed)




Simcenter STAR-CCM+ v.11.04 provides the EBU model as an option for Premixed Combustion. However, this model is the same as that provided for Partially-Premixed combustion. Further steps are required to restore the premixed behaviour that was available in Simcenter STAR-CCM+ v.11.02 and earlier. These steps are as follows:

In Simcenter STAR-CCM+ v11.02, the reactants and corresponding mass fractions are defined under the [Continuum] > Fluid Stream Manager node.

  1. In Simcenter STAR-CCM+ v11.02, you use the Fluid Stream Manager to set the species composition of a fuel and an oxidizer. In Simcenter STAR-CCM+ v11.04, you define the reaction framework as follows:
    1. Define the reactants and products for the reaction under the Models > Reacting > Reactions node. Make sure that you create one reaction between a fuel and an oxidizer and specify the products of the complete combustion.
      See Defining Chemical Reactions Manually.
    2. Specify stoichiometric coefficients for each component to represent a balanced complete combustion reaction.


    3. To specify the mass fractions of each component, select the [Continuum] > Initial Conditions > Species Mass Fraction node.
    4. For the Value property, specify the mass fractions of each species in the composition of the initial mixture.


In Simcenter STAR-CCM+ v11.02, the Eddy Break-Up Coefficients are defined under the Models > Eddy Break-Up > Premixed EBU rate coefficient, A node.

In Simcenter STAR-CCM+ v11.04 or later, the Eddy Break-Up Coefficients are defined in the general reactions framework.
  1. Select the Models > Eddy Break-Up node and set Reaction Control to Standard EBU.
  2. Define the EBU rate coefficient A to suit Simcenter STAR-CCM+ v11.04 or later—this value is different from the value that is set for the Premixed EBU rate coefficient A in Simcenter STAR-CCM+ v11.02.
    1. Expand the Models > Reacting > Reactions > [Reaction] > Properties node.
    2. Select the Properties > EBU Coefficients > EBU Rate Coefficient, A node and specify the Value.
  3. To restore the Ignitor:
    1. Right-click the [Continuum] > Ignitors node and select New > EBU Ignitor.
    2. Select the EBUIgnitor 1 node and specify the properties as they are set in Simcenter STAR-CCM+ v11.02.
    3. If the EBUIgnitor 1 node Activator is set to Pulse, select the Pulse sub-node and specify the necessary properties.
  4. For all inlet and outlet boundaries within each physics continuum, select the [Boundary] > Physics Values > Species Mass Fraction node and specify the mass fractions of each species with the same values as are specified in the initial conditions.