Release from Data File
Use a Release from Data File node to release particles by specifying the initial position, velocity, and values of auxiliary dependent variables using data from a text file.
Go to Release for information about the following sections: Release Times, Release Current Magnitude, Mass Flow Rate, Released Particle Properties, Initial Particle Temperature, Initial Multiplication Factor, and Advanced Settings.
Formatting Guidelines for Files Containing Particle Data
The imported data file should be a text file (*.txt) arranged in a spreadsheet format; that is, each row corresponds to a distinct particle and should have the same number of columns as all other rows. Columns can be separated by spaces, tabs, or a combination of the two. Begin a line with the percent (“%”) character to include comments or empty lines in the data file.
For example, a data file containing the following text would insert particles at the positions (0.1, 0.2, 0.6) and (0.2, 0.4, 0.8) in a three-dimensional geometry:
% Initial particle positions
% qx0 qy0 qz0
0.1 0.2 0.6
0.2 0.4 0.8
Initial Position
Browse your computer to select a text file, then click Import to import the data. To remove the imported data, click Discard. Enter the Index of first column containing position data i to indicate which column represents the first coordinate of the particle position vectors. The default value, 0, indicates the first column.
Transformations
The distribution of loaded particle positions may be scaled, rotated, and translated before the particles are released.
To scale the distribution of release positions, enter a value or expression for the Scale factor R (dimensionless). The default is 1. This scale factor can be used to correct unit discrepancies between the data file and the model geometry. For example, if the geometry length unit is in meters but the data file lists coordinates in millimeters, enter a scale factor of 0.001.
To rotate the distribution, enter the Euler angles (Z-X-Z) α, β, and γ (in 3D) or the Rotation angle α (in 2D). The default values are all 0.
In 3D, α is the rotation angle about the space-fixed z-axis, then β is the rotation angle about the transformed x-axis (or x’-axis), and finally γ is the rotation angle about the transformed z-axis (or z’’-axis). Positive values indicate counterclockwise rotations.
Enter values or expressions for the components of the Displacement vector Δq (SI unit: m). The default is not to apply any translation.
If a translation and another type of transformation (scaling or rotation) are applied, then the translation is always applied after the other transformations.
Initial Velocity
Select an option from the Initial velocity list: Expression (the default), From file, Kinetic energy and direction, Constant speed, spherical, Constant speed, hemispherical, Constant speed, cone, Constant speed, Lambertian (3D only), or Maxwellian.
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For From file, enter the Index of first column containing velocity data i. The default is 3. The columns are zero-indexed; that is, an index of 0 corresponds to the first column. If you chose to rotate the initial particle positions in the Transformations section, select the Rotate velocity vectors check box to apply the same rotation to the initial velocity vectors of the released particles. The check box is cleared by default.
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For all other options, the settings are the same as for the Release node.
Initial Particle Mass
This section is only available for The Particle Tracing for Fluid Flow Interface and is only shown when Specify particle mass is selected from the Particle size distribution list in the physics interface Additional Variables section.
The initial particle mass can be a single value or can be sampled from a distribution. Select an option from the Distribution function list: From file, None (the default), Normal, Lognormal, Uniform, or List of values.
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When From file is selected, enter the Index of column containing mass data. The default value is 3. The columns are zero-indexed; that is, an index of 0 corresponds to the first column.
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For all other options, the settings are the same as for the Release node.
Initial Particle Diameter
This section is only available for The Particle Tracing for Fluid Flow Interface and is only shown when Specify particle diameter is selected from the Particle size distribution list in the physics interface Additional Variables section.
The initial particle diameter can be a single value or can be sampled from a distribution. Select an option from the Distribution function list: From file, None (the default), Normal, Lognormal, Uniform, or List of values.
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When From file is selected, enter the Index of column containing mass data. The default value is 3. The columns are zero-indexed; that is, an index of 0 corresponds to the first column.
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For all other options, the settings are the same as for the Release node.
Initial Value of Auxiliary Dependent Variables
This section is available if an Auxiliary Dependent Variable has been added to the model.
For each of the active Auxiliary Dependent Variable nodes in the model, choose an option from the Distribution function list: From file, None (the default), Normal, Lognormal, Uniform, or List of Values.
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When From file is selected, enter the Index of column containing data. The default value is 3. The columns are zero-indexed; that is, an index of 0 corresponds to the first column.
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For all other options, the settings are the same as for the Release node.