Defining Chemical Reactions Manually

The Models > Reacting > Reactions node and the Reacting Surface > Reactions node allow you to define reactions which occur within the reacting flow.

Before defining chemical reactions manually, make sure that species are defined under the relevant materials node. See Defining Species Manually or Importing Species and Reactions.

In Simcenter STAR-CCM+, you can define simple reacting flow chemistry definitions manually. You can define reaction components as reactants or products, however, it is not possible to define any intermediate reaction components manually. If it is important to define specific intermediate reaction components in the chemistry definition, you can import an externally compiled reaction mechanism. See Importing Species and Reactions.

To set up a new reacting flow chemistry definition, right-click the Reactions node and select New Reaction.
A [Reaction n] sub-node appears.
Define the reaction components:
1. Right-click the [Reaction n] > Reactants node and select Add Reactant.
2. Select a reactant from the submenu.
  The menu displays components that are already defined as part of the mixture and not already selected as a reactant in this reaction.
3. Select any further reactants for the reaction.
4. Right-click the [Reaction n] > Products node and select Add Product.
5. Select products from the submenu in the same manner as for the reactants.
Specify the properties of each reaction component.
1. Set stoichiometric coefficients, $ν_{i j}$ , that are appropriate to the reaction.
  Make sure that the stoichiometric coefficients represent the correct ratio of reactants and products as are defined in the balanced chemical equation.
2. For the EBU model and surface chemistry reactions, specify a rate exponent, $p_{i j}$ .
  This parameter is used to calculate chemical reaction rates from finite-rate kinetics—not required if the Standard EBU model is used for Eddy Break-up.
Repeat the steps above until all reactions that are required to describe the reacting flow chemistry definition are fully defined.
If necessary, define the overall properties for the reacting flow chemistry definition. Expand the [Reaction n] > Properties node.
- When using the Eddy Break-Up (EBU) model, expand the Properties > EBU Coefficients node and specify the EBU rate coefficients.
- When using other reacting flow models, expand the Properties > Reaction Coefficient node and specify the Arrhenius coefficients or User-defined reaction coefficient.