Reactants and products are specified in terms of parent and child materials. The
parent material defines the phase in which species react, and the child materials
represent the reacting species. For this release of Ansys CFX, reactants from
different phases can only be specified for the char oxidation reactions
(Field Char Oxidation or Gibb Char
Oxidation). Arrhenius type multiphase reaction rates require that all
reactants belong to the same phase. The stoichiometry for multiphase reactions is
specified by means of mass coefficients rather than stoichiometry coefficients
referring to moles.
As an example, consider a simplified case of coal reacting with oxygen in the
reaction 
. The Parent Materials List
on the Reactants tab contains two materials,
Coal (a pure substance containing carbon) and
Gas mixture (a variable composition mixture containing
O2, CO2 and
N2). The child material for Coal
would be set to Carbon, and the child material for
Gas Mixture would be set to O2. It
follows that on the Products tab, the Materials
List contains Gas Mixture as the parent
material, which in turn would contain CO2 as its
child.
Note: The above is presented only as an illustration of the use of the parent/child material structure.