Modeling Dispersed Multiphase Flow
Dispersed Multiphase (DMP) is an alternative to the Lagrangian Multiphase (LMP) model and the Eulerian Multiphase (EMP) models, rather than a replacement. Due to its superposing behavior, DMP is compatible with many existing single-phase models. The dispersed phase particles can exist in a background fluid that is a single- or multi-component gas or liquid. The particles themselves can be single-component gases or liquids.
The Dispersed Multiphase model can be activated at the end of a simulation without the need to deactivate and reactivate the appropriate set of models. As DMP does not solve for the background flow, it is automatically compatible with both segregated and coupled solution of the background flow and energy.
DMP can be used as a post-processing tool: you can clear the Dispersed Multiphase solution, leaving the background flow intact, and then recalculate the transport of the dispersed phases only. You can obtain a steady solution even when the entire simulation is Unsteady.
This feature can help you to perform a quick analysis of particle behavior, such as collection efficiencies. For example, if you are using a set of dispersed phases to model a range of particle diameters, you can repeat the calculation for each dispersed phase and sum the results.
To set up a simulation that uses the Dispersed Multiphase model:
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Right-click the node and select the following models:
Group Box
Model
Space
Select one of: -
Axisymmetric
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Three Dimensional (required for Adaptive Mesh)
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Two Dimensional
Time
Select one of: -
Steady
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PISO Unsteady (for Volume of Fluid (VOF) only)
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Implicit Unsteady
Material
Select one of :- Gas
- Liquid
Multiphase Interaction
Multiphase Model Select one of : - Two-Phase Equilibrium (EMP)
- Mixture Multiphase (MMP)
- Volume of Fluid (VOF).
Viscous Regime Select one of: -
Laminar
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Turbulent
Flow For the Two-Phase Thermodynamic Equilibrium model only, choose one of the following: -
Segregated Flow
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Coupled Flow
Optional Models Dispersed Multiphase (DMP) See Dispersed Multiphase Model Reference.
The Non-Equilibrium Condensation model becomes available in the phase interaction.Adaptive Mesh—Use this model if you want to refine the mesh locally and select user-defined refinement criteria that query the flow solution as the simulation runs to reduce the computation time.
Select the User-Defined Mesh Adaption criteria and specify the appropriate properties.
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Define the dispersed phases.
Each dispersed phase is a Eulerian phase for which you specify the relevant models, such as a flow model, a heat transport model, and a material model. You can also specify whether each phase is two-way coupled with the background phase. You can use a number of dispersed phases to model particles of different materials, or particles that are of a single material but of different sizes. Each dispersed phase is independent: the phases do not interact.
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Set up the phase interactions.
You can set up interactions between the dispersed phase and the background (continuous phase), between the dispersed phase and a fluid film, and between the dispersed phase and a VOF phase.
See Setting Up Phase Interactions.
To model condensation, set up the DMP phase as gas, and ensure that the Discrete Quadrature S-Gamma model is activated. Select the Non-Equilibrium Condensation model in phase interactions. See Non-Equilibrium Condensation.
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Set boundary and region conditions.
The boundary conditions are typically set as phase conditions of the dispersed phase. The available methods to specify the velocity, volume fraction, and temperature depend on the type of boundary.
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Set the Dispersed Multiphase solver parameters.
The Dispersed Multiphase solvers generally use the same techniques as the Segregated Flow solvers.
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Set up any monitors, plots, and scenes that you require.
For example, you can monitor the Volume Fraction of each phase.
- Run the simulation.