23.1.6. Particles Tab

The Particles tab for the Output Control object contains settings that specify whether the particle data is recorded, and details of how the data is collected and recorded.

This tab is available only when the morphology option is set to Particle Transport Fluid or Particle Transport Solid in CFX-Pre; for details, see Basic Settings Tab.

The particle data is initially written to particle track files, which contain a specified level of detail about particles involved in your simulation. The files are written to the directory with the same name as your current run. An option on the Particles tab controls whether or not the track files are retained after their data is copied into the final results file (and any backup results files).

 

23.1.6.1. Particle Track File Check Box

This check box determines whether or not to customize the type and amount of particle track data recorded in the results file.

 
23.1.6.1.1. Option

  • All Track Positions (default)

    Point data is collected for all track positions, as determined by the Track Positions setting.

  • Specified Position Interval

    Point data is collected for a subset of all track positions. The entire set of track positions is determined by the Track Positions setting. The subset is controlled by the Interval setting. For example, if Track Position Interval is left at its default value of 1, then the result is the same as setting Option to All Track Positions. Setting Interval to 2 will cause point data to be collected for every second track position; setting Interval to 3 will cause point data to be collected for every third track position, and so on.

  • Specified Distance Spacing

    Point data is collected for evenly-spaced points along each track. The spacing is controlled by this parameter, and represents a physical distance.

  • Specified Time Spacing

    Point data is collected for points along each track with the points spaced by time according to this parameter. The physical distance between data collection points is therefore a function of the particle velocity along each track.

  • None

    This option can be used to avoid writing any track information. This might be useful if you are not interested in particle tracks or want to avoid the additional disk space required to store the tracks. If this option is set, no tracks will be available in CFD-Post. In contrast to the track file information, sources are required for a clean re-start of a particle case and must be written to the results file.

Note:  For a transient run, final particle positions are always added to the track information, and therefore can be seen at the end of a run.

 
23.1.6.1.2. Track Positions Check Box

(applies only when Particle Track File Check Box: Option is set to All Track Positions or Specified Position Interval)

This check box determines whether the Track Positions setting will be specified or left at the default value: Element Faces.

 
23.1.6.1.3. Track Positions Check Box: Track Positions

  • Control Volume Faces

    Points are written each time a sub-control volume boundary is crossed. This produces the more precise and larger track files than the other option.

  • Element Faces

    Points are written to the track file each time a particle crosses the boundary of an element.

 
23.1.6.1.4. Interval

(applies only when Particle Track File Check Box: Option is set to Specified Position Interval)

Enter an integer that specifies the spacing (in terms of points) between points along the tracks.

 
23.1.6.1.5. Track Distance Spacing

(applies only when Particle Track File Check Box: Option is set to Specified Distance Spacing)

Enter a numerical quantity that specifies the physical distance interval between successive points on the track. Data will be collected only for those points.

 
23.1.6.1.6. Track Time Spacing

(applies only when Particle Track File Check Box: Option is set to Specified Time Spacing)

Enter a numerical quantity that specifies the physical time interval between successive points on the track. Data will be collected only for those points.

 
23.1.6.1.7. Track Printing Interval Check Box

This check box determines whether the Track Printing Interval setting will be specified or left at the default value: 1.

 
23.1.6.1.8. Track Printing Interval Check Box: Interval

Output data is collected for every nth particle track, where n is the specified number.

 
23.1.6.1.9. Keep Track File Check Box

This check box determines whether or not the track files are kept. When the track files are kept, they can be found below the working directory in a directory that has the same name as the run. For example, for the first solution of dryer.def, the track files are kept in a directory called dryer_001.

The data will be copied into the results file regardless of whether or not the track files are kept. CFD-Post can extract the track file data from the results file for postprocessing.

 
23.1.6.1.10. Track File Format Check Box

This check box determines whether the track file format will be specified, or left at the solver default value: Unformatted. The track file will remain in the working directory after finishing a run only if you select the Keep Track File option to force the solver to not delete it.

 
23.1.6.1.11. Track File Format Check Box: Track File Format

  • Formatted

    Formatted track files are in human-readable ASCII format but take up much more disk space than unformatted track files.

    The general structure of formatted ASCII track files will print the Number of Particle Positions in a Block at the top of the file preceding repetitions of the following:

    Particle Track Number
X Position
Y Position
Z Position
Traveling Time
Traveling Distance
Particle Diameter
Particle Number Rate
Particle Mass Fraction Component 1
Particle Mass Fraction Component 2
....
Particle Mass Fraction Component n
Particle U Velocity
Particle V Velocity
Particle W Velocity
Particle Temperature
Particle Mass

    Note:  Particle Mass Fraction Component 1- n only appear for multi-component particle materials and Particle Temperature only appears when heat transfer is activated.

  • Unformatted

    Unformatted track files are written in a non-readable, binary, format.

 

23.1.6.2. Particle Histogram

This option allows you to define particle histogram data of track variables on user-specified boundary patches and/or particle injection regions.

In steady-state, particle histograms are written/overwritten each time particles are tracked. In transient simulations, particle histograms are over written within a time step loop (i.e. coefficient loops). The histograms of the last coefficient loop of a time step is stored in the run directory.

 
23.1.6.2.1. Histogram Type

Each of the histogram types are obtained by splitting the range of data into bins of equal size. The main difference between each type is the method in which the data is counted.

  • Raw

    For each bin, you count the number of points from the data set that fall into each bin.

  • Normalized

    For each bin in the Normalized histogram, you normalize the count in terms of the total number of observations.

  • Accumulated

    In the Accumulated histogram, the vertical axis count is a cumulative count of the current bin plus all bins for smaller values of the response variable.

  • Accumulated and Normalized

    For the Accumulated and Normalized histogram option, the vertical axis count is a cumulative normalized count of the current bin plus all bins for smaller values of the response variable.

 
23.1.6.2.2. Number of Bins

Number of discrete intervals or classes that accumulate data is divided into based on the frequency of the data.

 
23.1.6.2.3. Particle Definition

The Particle Definition allows you to select the particle type for which the histogram output is created. x and y variable lists only show particle track variables filtered according to the particle type selected in Particle Definition.

 
23.1.6.2.4. x Variable

The response variable. Any valid particle track variable is supported. Response variables outside of the user specified min/max limits are stored in bins '1' or 'n'.

 
23.1.6.2.5. y Variable

The count variable. For the Raw histogram type, this variable can hold any particle track variable. For all other histogram types, this variable is restricted to the particle number rate option only.

Note:  Particle number rates are evaluated without distinguishing incoming particles from outgoing particles.

 
23.1.6.2.6. x Var. Lower Bound

Lower bound for histogram response variable (X axis). Histogram lower bound variables use context-sensitive dimensions that depend on the dimension of y-variable specified.

 
23.1.6.2.7. x Var. Upper Bound

Upper bound for histogram response variable (X axis). Histogram upper bound variables use context-sensitive dimensions that depend on the dimension of y-variable specified.

 
23.1.6.2.8. Sample Location

Specify a boundary patch or particle injection region against which the histogram will be plotted.

Note:  You can only select individual boundary patches or particle injection regions in CFX-Pre.

 
23.1.6.2.9. Export Format

All particle histogram data is written to file in a CFX CSV Histogram format. You can specify the output file name in CCL using the Filename Prefix option. If no user-defined filename can be found, the following file naming convention applies:

  • Steady-state run:

    <Particle Type Alias Name>_<Histogram Alias Name>.csv

    For example: MyParticle_Histo1.csv

  • Transient run:

    <Particle Type Alias Name>_<Histogram Alias Name>_<Timestep Number>.csv

    For example: MyParticle_Histo2_3.csv

 
23.1.6.2.10. Export Frequency

Only supported export frequency option is: Every Timestep.

 

23.1.6.3. Transient Particle Diagnostics

This section is available for transient simulations using particle tracking and enables you to output various particle data; for details, see Transient Particle Diagnostics in the CFX-Solver Modeling Guide.

 

23.1.6.4. Transient Particle Diagnostics: List Box

Shows the current Transient Particle Diagnostics outputs. You can click   to create a new diagnostics output file or click   to delete an existing one.

 

23.1.6.5. Transient Particle Diagnostics: [Transient Particle Diagnostics Name]

 
23.1.6.5.1. Option

  • Particle Penetration

  • Total Particle Mass

  • User Defined - This option can be used to specify a user-defined Diagnostic Routine to evaluate the diagnostics information based on particle variables specified in Particle Variables List. Optionally, you can also select the Monitored Values List check box and specify a comma-separated list of names for monitored values. For details, see User Diagnostics Routine in the CFX-Solver Modeling Guide.

 
23.1.6.5.2. Particles List

Select particles to be used for output from the drop-down list, or click   and select from the Particles List dialog box.

 
23.1.6.5.3. Spray Mass Frac.

The fraction of the total spray mass contained within an imaginary cone, the half-angle of which is the spray angle. The cone tip is at the point of injection and the cone axis is parallel to the direction of injection.

 
23.1.6.5.4. Penetration Origin and Direction: Option

  • Specified Origin and Direction

 
23.1.6.5.5. Penetration Origin and Direction: Injection Center

Enter the Cartesian coordinates of the center of injection.

 
23.1.6.5.6. Penetration Origin and Direction: Injection Direction
 
23.1.6.5.6.1. Option

  • Cartesian Components

    Specify the Cartesian components (Direction X Comp., Direction Y Comp., and Direction Z Comp.) of the injection direction.

 
23.1.6.5.7. Axial Penetration: Option
 
23.1.6.5.8. Radial Penetration: Option
 
23.1.6.5.9. Normal Penetration: Option
 
23.1.6.5.10. Spray Angle: Option
 
23.1.6.5.10.1. Spray Angle: Spray Radius at Penetration Origin Check Box

Enable to specify a spray radius for the penetration origin.

 
23.1.6.5.10.2. Spray Angle: Spray Radius at Penetration Origin Check Box: Spray Radius

Enter a penetration origin spray radius.