Wall
The Wall is the default boundary condition on all exterior boundaries. This boundary condition stops particles that hit a surface. By default, the Freeze condition is used.
Choose any of the following from the Wall condition list. This affects the type of information that is accessible while evaluating and visualizing the results.
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Freeze (the default): all information about the particles can be evaluated during postprocessing.
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Stick: only the particle position can be evaluated during postprocessing. Other particle-based quantities, such as auxiliary variables, will be evaluated as zero.
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Disappear: the particle is removed from the geometry when it hits a surface. Any quantity that is evaluated on the particle after this time will evaluate to not-a-number (NaN).
Select one of the following from the Primary particle condition list: None (the default), Probability, or Expression. For Probability or Expression, select an option from the Otherwise list: Freeze (the default), Stick, or Disappear.
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For Probability, enter a value or expression for the Probability γ (dimensionless). The default is 0. For each particle that hits the wall, there is a probability of γ that it will be affected by the Wall condition, and a probability of 1 − γ that it will be affected by the behavior chosen from the Otherwise list.
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For Expression, enter a value or expression for the Evaluation expression e (dimensionless). The default is 1. For each particle that hits the wall, the Wall condition will be used if the expression has a nonzero value (here nonzero is considered “true”) or will be affected by the Otherwise setting if the value is zero.