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    • Documentation

    SimScale DocumentationAnalysis TypesMulti-purpose AnalysisMulti-purpose Multicomponent

    Multi-purpose Multicomponent

    The Multicomponent mixing model is used for analyzing the mixing of different types of gases. The gases mix at a molecular level and the mixing model differs from the Volume of Fluid multiphase model where the phases are immiscible. For example, the mixing of dry air movement with moist air is a multicomponent flow, whereas oil-water simulation is multiphase with a distinct interface between oil and water.

    The Multicomponent model, inside the Multi-purpose solver, captures the mixing and transport of different gaseous components through convection and diffusion, without considering chemical reactions. In this model, the bulk motion of the flow is solved for the combined velocity, pressure, and temperature, while each constituent component’s mass concentration is obtained by solving an additional transport equation.

    Setup of the Multicomponent Model in SimScale Workbench

    To activate this model, toggle on Multicomponent under global settings.

    Figure 1: Activating the Multicomponent model in the global settings panel

    The mixing of gases is always treated as a compressible flow. This is because properties like density, viscosity, and thermal conductivity become important and influence the flow. The Compressible toggle will be activated by default as the Multicomponent toggle is turned on.

    Muticomponent vs Multiphase

    Note that the Multicomponent and Multiphase models are mutually exclusive and cannot be used together. 

    Multicomponent vs Passive Scalars

    Passive scalars do not account for mass and material properties of the constituent components. While in the multicomponent model, the individual material properties of the component gases have a bearing on the flow patters and distribution of the component itself. These properties include density, viscosity and thermal properties.

    Material Properties

    The Multicomponent model only allows gases. Even if you choose a liquid from the material library, it will be treated in its gaseous/vapor form.

    list of materials for multicomponent multi-purpose
    Figure 2: List of materials that can be used when performing a Multi-purpose analysis with the multicomponent mixing model

    The user needs to assign a new material to each gaseous component present in the simulation. It could be the same material with different properties or different materials altogether.

    multicomponent analysis material input
    Figure 3: Multiple material input for the multicomponent model

    Applications

    Some examples of simulations where the Multicomponent model can be used are

    • CO2 emission from a chimney stack,
    • Smoke dispersion,
    • Static gas mixers,
    • Gas tank simulations, etc. 

    Last updated: September 20th, 2024

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