## 1.5. Mixture Properties (Fixed, Variable, Reacting)

By default, for fixed composition, variable composition, and reacting mixtures, all mixture properties use the `Ideal Mixture` option. With this option, a mixture property (or its inverse, for the cases of density and molar mass) is computed as a mass-weighted average of the component properties (or their inverses, for the cases of density and molar mass).

In order to set options other than `Ideal Mixture` for the Thermodynamic Properties, select Mixture Properties in the Mixture Properties tab in the Material details view and set Option to `Non Ideal Mixture`. When the global option is set to `Non Ideal Mixture`, individual properties may still be set to use the ideal mixture rule by selecting `Ideal Mixture` for the respective property.

Details of the non-ideal mixture options are described in the following subsections:

- Equation of State/Density
- Molar Mass
- Specific Heat Capacity
- Electromagnetic Properties

Release 18.2 - © ANSYS, Inc. All rights reserved.