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22.16.6 Sampling of Trajectories

Particle states (position, velocity, diameter, temperature, and mass flow rate) can be written to files at various boundaries and planes (lines in 2D) using the Sample Trajectories panel (Figure  22.16.2).

Report $\rightarrow$ Discrete Phase $\rightarrow$ Sample...

Figure 22.16.2: The Sample Trajectories Panel

The procedure for generating files containing the particle samples is listed below:

1.   Select the injections to be tracked in the Release From Injections list.

2.   Select the surfaces at which samples will be written. These can be boundaries from the Boundaries list or planes from the Planes list (in 3D) or lines from the Lines list (in 2D).

3.   Click on the Compute button. Note that for unsteady particle tracking, the Compute button will become the Start button (to initiate sampling) or a Stop button (to stop sampling).

Clicking on the Compute button will cause the particles to be tracked and their status to be written to files when they encounter selected surfaces. The file names will be formed by appending .dpm to the surface name.

For unsteady particle tracking, clicking on the Start button will open the files and write the file header sections. If the solution is advanced in time by computing some time steps, the particle trajectories will be updated and the particle states will be written to the files as they cross the selected planes or boundaries. Clicking on the Stop button will close the files and end the sampling.

For stochastic tracking, it may be useful to repeat this process multiple times and append the results to the same file, while monitoring the sample statistics at each update. To do this, enable the Append Files option before repeating the calculation (clicking on Compute). Similarly, you can cause erosion and accretion rates to be accumulated for repeated trajectory calculations by turning on the Accumulate Erosion/Accretion Rates option. (See also Section  22.16.9.) The format and the information written for the sample output can also be controlled through a user-defined function, which can be selected in the Output drop-down list. See the separate UDF Manual for information about user-defined functions.

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