Specifies parameters for the output of particle and flow values at the particle seed locations.


AcuTrace Command




This command has no qualifier.


active (boolean) [=off]
Flag specifying if interpolate output is active.


Interpolate output is a legacy output type provided for backward capability.

Interpolate output does not require any particle tracing. It records the values of the particle and flow outputs at the particle seed locations at the earliest seed time. The output is written to one or more files with extension .pin in the working directory.

Interpolate output can be useful for determining which particle seeds are in the flow domain. Only seeds that are in the flow domain are recorded in the .pin files. To use interpolate output for this purpose, it is recommended that format be set to ascii and that AcuRunTrace be run in serial mode in which case a single .pin file is written.

The active, flow_state_data, and flow_gradient_data parameters control what information is recorded. No trace output is recorded unless active = on. By default, all particle outputs and no flow outputs are recorded when trace output is active.

Particle values are the state of the particle, that is, its position, time, particle velocity, and so on. The flow outputs are found by interpolating the AcuSolve flow field to the current position and time of the particle.

Particle outputs always include

  • Seed ID
  • Coordinates
  • Time
  • Particle velocity
  • Element ID
  • Element set ID
  • Marker
  • Particle velocity magnitude
  • Trace length

They also include

  • Particle mass
  • Particle density
  • Particle radius

if the parameter particle equals finite_mass model in the EQUATION command,

  • Component values

if the parameter number_particle_components in the EQUATION command is non-zero,

  • User equation values

if one or more user equations are specified by the user_equations parameter of the EQUATION command.

  • Turbulence random seed

if the parameter turbulent_trace equals on in the TRACE_PARAMETERS command and

  • Stretch vector
  • Stretch magnitude
  • Log stretch magnitude
  • Stretch rate magnitude

if the parameter stretch does not equal none in the EQUATION command.

Flow state values always include

  • Flow velocity
  • Flow pressure
  • Flow velocity magnitude
  • Flow strain rate magnitude

They also include

  • Flow temperature
  • Flow species
  • Flow eddy viscosity

if these are available in the AcuSolve database.

Flow gradient values currently include only

  • Gradient of flow velocity

Note that for the massless particle motion equation, the particle and the flow velocity fields are identical except possibly for particle positions in elements next to a wall.