23.4 Setting Boundary Conditions for the Discrete Phase

When a particle reaches a physical boundary (e.g., a wall or inlet boundary) in your model, ANSYS FLUENT applies a discrete phase boundary condition to determine the fate of the trajectory at that boundary. One of several contingencies may arise:

• The particle may be reflected via an elastic or inelastic collision.

• The particle may escape through the boundary. The particle is lost from the calculation at the point where it impacts the boundary.

• The particle may be trapped at the wall. Nonvolatile material is lost from the calculation at the point of impact with the boundary; volatile material present in the particle or droplet is released to the vapor phase at this point.

• The particle may pass through an internal boundary zone, such as radiator or porous jump.

• The particle may slide along the wall, depending on particle properties and impact angle.

• The particle may form a film (Wall-Film Model).

You also have the option of implementing a user-defined function to model the particle behavior when hitting the boundary. More information about user-defined functions can be found in the separate UDF Manual.

The boundary condition, or trajectory fate, can be defined separately for each zone in your ANSYS FLUENT model.