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22.13.1 Discrete Phase Boundary Condition Types

The available boundary conditions, as noted in Section  22.10, include the following:

It is also possible to use a user-defined function to compute the behavior of the particles at a physical boundary. See the separate UDF Manual for information about user-defined functions.

Because you can stipulate any of these conditions at flow boundaries, it is possible to incorporate mixed discrete phase boundary conditions in your FLUENT model.

Discrete phase boundary conditions can be set for boundaries in the panels opened from the Boundary Conditions panel. When one or more injections have been defined, inputs for the discrete phase will appear in the panels (e.g., Figure  22.13.5).

Figure 22.13.5: Discrete Phase Boundary Conditions in the Wall Panel

Select reflect, trap, escape, wall-jet, or user-defined in the Boundary Cond. Type drop-down list under Discrete Phase Model Conditions. (In the Walls panel, you will need to click on the DPM tab to access the Discrete Phase Model Conditions.) If you select user-defined, you can select a user-defined function in the Boundary Cond. Function drop-down list. For internal boundary zones, such as a radiator or a porous jump, you can also choose an interior boundary condition. The interior condition means that the particles will pass through the internal boundary.

If you select the reflect type at a wall (only), you can define a constant, polynomial, piecewise-linear, or piecewise-polynomial function for the Normal and Tangent coefficients of restitution under Discrete Phase Reflection Coefficients. See Section  22.13.1 for details about the boundary condition types and the coefficients of restitution. The panels for defining the polynomial, piecewise-linear, and piecewise-polynomial functions are the same as those used for defining temperature-dependent properties. See Section  8.2 for details.

Default Discrete Phase Boundary Conditions

FLUENT makes the following assumptions regarding boundary conditions:

The coefficient of restitution can be modified only for wall boundaries.

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