Multicomponent Mixing—Introduction
Multicomponent flows consist of different chemical species or components that are mixed at the molecular level and generally have the same velocity and temperature. They differ from multiphase flows of the Multiphase module where the different phases are intrinsically immiscible (though turbulent mixing can occur), and each phase only occupies a fraction of the total volume.
For example, the air around us consists of two main chemical components, oxygen, and nitrogen, and some water vapor depending on humidity. They are fully mixed and occupy the same space. The air movement or wind is thus a multicomponent flow. However, when you mix oil and water in a container, the water and oil are separated by a clear interface and water is at the bottom. The oil-water motions are liquid-liquid two-phase flows. Also, the chemical components can interact through chemical reactions and the resulting multicomponent reactive flows occur in various natural phenomena and engineering applications. Therefore, it is very important to consider multicomponent flows in a CFA solver.
Multicomponent Mixing is a module in Creo Flow Analysis that predicts the mixing and transport of multiple components by solving conservation equations which describe convection and diffusion for each component species. To access this module, follow these steps:
1. Right-click 
Physics and click Select Physics Models. The Physical Model Selection dialog box opens.
Physics and click Select Physics Models. The Physical Model Selection dialog box opens.2. Select the module from Available Modules. In the Flow Analysis Tree, under Physics, Multicomponent Mixing is added.
Multicomponent mixing is described in the sections that follow:
• Definitions—Terms used in radiation modeling.
• Physics—Definitions, terminology, constants, models, and methods used in multicomponent mixing.
• Conditions—Conditions specified for the entities such as boundaries, interfaces, volumes, and the outputs from the module.
• Output Variables—Expressions created for specifying conditions and postprocessing associated with multicomponent mixing.