Particles Exits

Particles Exits records every particle that leaves the system during the simulation. This output is active when Exit Statistics is active on the Bubbles/Particles Output Panel. Rather than reporting ensemble-averaged behavior, this output provides an event-by-event record of particle exits, including when each particle exited, where it exited, which exit it passed through, and the particle properties at the moment of exit. The name of this file is {DynamicName}_Exits.txt, where the dynamic name corresponds to the name of the Particle Family in the Model Tree.

Unlike most statistics outputs, Particles Exits is not written at a fixed output interval. Instead, entries are appended dynamically whenever a particle exits the domain. Each row corresponds to a single exit event, making this a discrete, event-driven dataset rather than a time-sampled one.

Statistics Table

The index table below shows the statistics that can appear in the Exit Age output file. Within this table, each statistic corresponds to a column in the output table that evolves with the time column.

Statistics	Units	Details	When Appears
Time	s	simulation time
Custom Variable	[dynamic]	custom variable magnitude
Custom Variable X	[dynamic]	custom variable value
Custom Variable Y	[dynamic]	custom variable value
Custom Variable Z	[dynamic]	custom variable value
Diameter	m	diameter
Exit Location	Dimensionless	location of exit
Exit Time	s	simulation time of exit
ParticleID	Dimensionless	unique ID
Position X	m	position of exit
Position Y	m	position of exit
Position Z	m	position of exit
Time Added	s	simulation time of original particle injection into system
Velocity X	m/s	velocity at exit
Velocity Y	m/s	velocity at exit
Velocity Z	m/s	velocity at exit
Volume	mm^3	volume including number scale

Usage and Interpretation

This output is primarily used to analyze outlet-specific particle behavior and system residence characteristics. Each exiting particle is tagged with an Exit Location (exit index) and a physical exit position. This enables analysis of inlet or outlet coupling, preferential flow paths, and how particle properties vary across different exits.

The Time Added and Exit Time fields define the residence time (exit age) of each particle. The distribution of these exit ages can be used to compute the residence time distribution (RTD).

Because all particle properties are recorded at the moment of exit, this output enables detailed analysis of particle fate as a function of particle properties.