33.5.2 Secondary Phase Dialog Box

The Secondary Phase dialog box allows you to set the properties of a secondary phase. It is opened from the Phases task page. The items that appear in the Secondary Phase dialog box will depend on which multiphase model you are using. See Sections  24.3.4, 24.4.1, and 24.5.2 for details about the items below.

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 Edit Material dialog box 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.

Partial Differential Equation   enables partail differential equation model for granular temperature. See this section in the separate Theory Guide for details.

Interfacial Area Concentration   is used to predict mass, momentum and energy transfers through the interface between the phases. See this section in the separate Theory Guide for details.

Properties   contains a list of phase-specific properties. This section of the dialog box 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 this equation in the separate Theory Guide). You can select constant (the default) in the drop-down list and specify a constant value, select syamlal-obrien to compute the value using this equation in the separate Theory Guide , select gidaspow to compute the value using this equation in the separate Theory Guide , or select user-defined to use a user-defined function.

Granular Bulk Viscosity   specifies the solids bulk viscosity ( $\lambda_q$ in this equation in the separate Theory Guide). 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 this equation in the separate Theory Guide , 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 this equation in the separate Theory Guide). 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 this equation in the separate Theory Guide , johnson-et-al, 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 ( this equation in the separate Theory Guide). This parameter is relevant only if you have selected schaeffer, johnson-et-al, or user-defined for the Frictional Viscosity.

Frictional Pressure   specifies the pressure gradient term, $\nabla P_{friction}$, in the granular-phase momentum equation. Choose none to exclude frictional pressure from your calculation, johnson-et-al to apply this equation in the separate Theory Guide , syamlal-obrien to apply this equation in the separate Theory Guide , based-ktgf, where the frictional pressure is defined by the kinetic theory [ 19]. The solids pressure tends to a large value near the packing limit, depending on the model selected for the radial distribution function. You must hook a user-defined function when selecting the user-defined option. See the separate UDF manual for information on hooking a UDF.

Frictional Modulus   can be set as derived, or as a user-defined function. This is defined as Equation  24.4-1.

Friction Packing Limit   specifies a threshold volume fraction at which the frictional regime becomes dominant. It is assumed that for a maximum packing limit of 0.6, the frictional regime starts at a volume fraction of about 0.5.

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

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 ANSYS 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.

Surface Tension   specifies the attractive forces between the interfaces.

Coalescence Kernel   allows you to specify the coalescence kernel. You can select none, constant, hibiki-ishii, ishii-kim, or user-defined. The two options, hibiki-ishii and ishii-kim, are described in detail in this section in the separate Theory Guide.

Breakage Kernel   allows you to specify the breakage kernel. You can select none, constant, hibiki-ishii, ishii-kim, or user-defined. The two options, hibiki-ishii and ishii-kim, are described in detail in this section in the separate Theory Guide.

Dissipation Function   gives you the option to choose the formula which calculates the dissipation rate used in the hibiki-ishii and ishii-kim models. You can choose amongst constant, wu-ishii-kim, fluent-ke, and user-defined for the dissipation function.

Hydraulic Diameter   is the value used in Equation  24.4-3. This is available when the wu-ishii-kim formulation is selected as the Dissipation Function.

Min/Max Diameter   are the limits of the bubble diameters.