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32.3.16 Define/Phases...

The Define/Phases... menu item opens the Phases panel.



Phases Panel


The Phases panel allows you to define each of the phases and the interaction between them. See Sections  23.9.3- 23.12.2 for details about the items below.

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Controls

Phase   contains a list of all of the phases in the problem from which you can select the phase you want to define or modify.

Type   displays whether the selected Phase is the primary-phase or a secondary-phase. This list is informational only. You cannot change a phase from primary to secondary, or vice versa; you can instead redefine the properties of the primary phase to reflect the new phase designated as primary, and redefine the secondary phases accordingly as well.

Interaction...   opens the Phase Interaction panel, where you can define the interaction between the phases (e.g., surface tension if you are using the VOF model, slip velocity functions if you are using the mixture model, or drag functions if you are using the Eulerian model).

ID   displays the ID number of the phase. You will need this number only if you are writing a user-defined function. See the separate UDF Manual for details about writing user-defined functions for multiphase applications.

Set...   opens the Primary Phase panel or the Secondary Phase panel, where you can define the properties of the selected primary or secondary phase.



Primary Phase Panel


The Primary Phase panel allows you to set the properties of the primary phase. It is opened from the Phases panel. See Section  23.10.3 for details about the items below.

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Controls

Name   specifies the name of the phase.

Phase Material   contains a drop-down list of available materials, from which you can select the appropriate one for this phase.

Edit...   opens the Material panel for the selected Phase Material, where you can modify its properties.



Secondary Phase Panel


The Secondary Phase panel allows you to set the properties of a secondary phase. It is opened from the Phases panel. The items that appear in the Secondary Phase panel will depend on which multiphase model you are using. See Sections  23.10.3, 23.11.1, and 23.12.2 for details about the items below.

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Controls

Name   specifies the name of the phase.

Phase Material   contains a drop-down list of available materials, from which you can select the appropriate one for the phase.

Edit...   opens the Material panel for the selected Phase Material, where you can modify its properties.

Granular   indicates whether or not this is a solid phase. This item appears only for the Eulerian model.

Packed Bed   indicates whether or not the granular phase is a packed bed. This option appears only if Granular is enabled.

Granular Temperature Model   lists the granular temperature models.

Phase Property   enables phase property model for granular temperature.

Partail Differential Equation   enables partail differential equation model for granular temperature. See Section  23.5.8 for details.

Properties   contains a list of phase-specific properties. This section of the panel will not appear for the VOF model. The Diameter appears for both the mixture model and the Eulerian model, but all of the others will appear only for a granular phase with the Eulerian model.

Diameter   specifies the diameter of the particles. You can select constant in the drop-down list and specify a constant value, or select user-defined to use a user-defined function. See the separate UDF Manual for details about user-defined functions.

Granular Viscosity   specifies the kinetic part of the granular viscosity of the particles ( $\mu_{s,{\rm kin}}$ in Equation  23.5-62). You can select constant (the default) in the drop-down list and specify a constant value, select syamlal-obrien to compute the value using Equation  23.5-64, select gidaspow to compute the value using Equation  23.5-65, or select user-defined to use a user-defined function.

Granular Bulk Viscosity   specifies the solids bulk viscosity ( $\lambda_q$ in Equation  23.5-6). You can select constant (the default) in the drop-down list and specify a constant value, select lun-et-al to compute the value using Equation  23.5-66, or select user-defined to use a user-defined function.

Frictional Viscosity   specifies a shear viscosity based on the viscous-plastic flow ( $\mu_{s,{\rm fr}}$ in Equation  23.5-62). By default, the frictional viscosity is neglected, as indicated by the default selection of none in the drop-down list. If you want to include the frictional viscosity, you can select constant and specify a constant value, select schaeffer to compute the value using Equation  23.5-67, or select user-defined to use a user-defined function.

Angle of Internal Friction   specifies a constant value for the angle $\phi$ used in Schaeffer's expression for frictional viscosity (Equation  23.5-67). This parameter is relevant only if you have selected schaeffer or user-defined for the Frictional Viscosity.

Granular Conductivity   specifies the solids conductivity. You can select syamlal-obrien, gidaspow, or user-defined.

Granular Temperature   specifies temperature for the solids phase and is proportional to the kinetic energy of the random motion of the particles. You can choose either the algebraic, the constant, or user-defined option.

Solids Pressure   specifies the pressure gradient term, $\nabla p_s$, in the granular-phase momentum equation. Choose either the lun-et-al, the syamlal-obrien, the ma-ahmadi, or the user-defined option.

Radial Distribution    specifies a correction factor that modifies the probability of collisions between grains when the solid granular phase becomes dense. Choose either the lun-et-al, the syamlal-obrien, the ma-ahmadi, the arastapour, or a user-defined option.

Elasticity Modulus    is defined as
 G = \frac{\partial P_s}{\partial \alpha_s} (32.3-1)

with $G \ge 0$.

Choose either the derived or user-defined options.

Packing Limit   specifies the maximum volume fraction for the granular phase ( $\alpha_{s,{\rm max}}$). For monodispersed spheres the packing limit is about 0.63, which is the default value in FLUENT. In polydispersed cases, however, smaller spheres can fill the small gaps between larger spheres, so you may need to increase the maximum packing limit.



Phase Interaction Panel


The Phase Interaction panel allows you to define the interaction between phases. It is opened from the Phases panel. The items that appear in the Phase Interaction panel will depend on which multiphase model you are using. (The panel shown below is for the VOF model.) See Sections  23.10.3, 23.11.1, and 23.12.2 for details about the items below.

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Controls

Wall Adhesion   enables the specification of a wall adhesion angle. (The angle itself, as defined in Figure  23.3.3, will be specified in the Wall panel.) This item will appear only for the VOF Model.

Virtual Mass   includes the "virtual mass force'' ( $F_{\rm vm}$ in Equation  23.5-9) that is present when a secondary phase accelerates relative to the primary phase. This item appears only for the Eulerian model.

Drag   displays the Drag Coefficient inputs. This tab is active only for the Eulerian model.

Drag Coefficient   specifies the drag function for each pair of phases. This section of the panel appears only for the Eulerian model. See Section  23.12.2 for information about the available options.

Lift   displays the Lift Coefficient inputs. This tab is active only for the Eulerian model.

Lift Coefficient   specifies the lift function for each pair of phases. This section of the panel appears only for the Eulerian model. See Section  23.12.2 for information about the available options.

Collisions   displays the Restitution Coefficient inputs. This tab is active only for the Eulerian model.

Restitution Coefficient   specifies the restitution coefficient for collisions between each pair of granular phases, and for collisions between particles of the same granular phase. It is relevant only if two or more granular phases are involved. See Section  23.12.2 for information about the available options.

Slip   displays the Slip Velocity inputs. This tab is active only for the mixture model.

Slip Velocity   specifies the slip velocity function for each secondary phase with respect to the primary phase. See Section  23.11.1 for information about the available options.

Heat   displays the Heat Transfer Coefficient inputs. This tab is active only for the Eulerian model when the energy equation is active.
Heat Transfer Coefficient   specifies the heat transfer coefficient function between each pair of phases. See Section  23.12.4 for information about the available options.

Mass   displays the Mass Transfer Function inputs.
Number of Mass Transfer Mechanisms   specifies the number of mass transfer mechanisms in your simulation. See Section  23.9.7 for information about the available options.

Cavitation   enables the calculation of cavitation effects as described in
Section  23.7.4.

Cavitation Parameters   contains parameters related to the cavitation model. This section of the panel will appear only when Cavitation is selected under Interphase Mass Transfer. See Section  23.11.2 for details.

Vaporization Pressure   specifies the value of $p_{sat}$ in Equations  23.7-13 and  23.7-14.

Non Condensable Gas Mass Fraction   specifies the mass fraction of non-condensable gases.

Surface Tension Coefficient   specifies the liquid surface tension.

Reactions   allows you to define multiple heterogeneous reactions and stoichometry.
Total Number of Heterogeneous Reactions   specifies the total number of reactions (volumetric reactions, wall surface reactions, and particle surface reactions). See Section  23.9.6 for information about the available options.

Reaction Name   allows you to enter a name for the reaction.

ID   enables you to set the reaction ID for each reaction.

Number of Reactants   allows you to specify the number of reactants that are involved in the reaction.

Number of Products   allows you to specify the number of products that are involved in the reaction.

Phase   drop-down list allows you to select the phase that is involved in the reaction.

Species   drop-down list allows you to select the species.

Stoich. Coefficient   allows you to set the stoichiometric coefficient.

Reaction Rate Function   allows you to choose a user-defined function for the reaction rate.

Surface Tension   includes the effects of surface tension along the fluid-fluid interface. This tab is active only for the VOF model.

Surface Tension Coefficients   specify the surface tension coefficient, $\sigma$ in Equation  23.3-14, for each pair of phases. See Section  23.10.3 for details.


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