The content of the Report subtab is determined by the choices made in the left panel of the Results tab. Change the values and settings therein and click Apply to generate an updated report. The chosen values are automatically stored in the *.gdr file. When the file is opened again later, it shows the last choice of post-processing parameters. Select Back-up result file in the left panel to save a copy of the current *.gdr file before modification. The back-up file will be located in the result folder and gets the file name AddiDictResult.gdr.bck## as an example for the default result file name AddiDictResult.gdr.
The main results of a Track Particles & Molecules simulation are statistics on the particle movement such as residence times, collisions with solids, or breakthrough and displacement.
If only diffusion is simulated, i.e., Simulate Advection is unchecked in the Experiment tab, the diffusivity is computed from the particle distances traveled. The Particle diffusivity is the diffusivity of all particles moving through the structure. The Effective diffusivity is the overall diffusivity of the structure. It takes into account that due to the microstructure, particles starting from somewhere outside of the computational domain will not all enter the structure. The Particle diffusivity (with Adsorption) is the diffusivity if an adsorption time is set for one or several materials.
The Time value shows the final time of the simulation run. By changing the Time Step, the user can choose at which times the particle positions are evaluated, i.e., how many rows appear in the tables shown in the report. To create an updated report, GeoDict reads the particle positions from the stored particle trajectory file. Bear in mind, that this file does not necessarily contain every intermediate position of the particles. Trajectories are only stored with the precision defined in the Output tab. Because the option Write at Given Time Steps in the output tab is always selected, it is guaranteed that the position of each particle is stored for the originally selected time steps. When the time steps chosen in the post-processing are not a subset of the original time steps, particle positions are interpolated, which might cause some loss of accuracy.
When the Compute Spatial Particle Distribution (*.num) box is checked, a particle concentration file is created for each Time Step. You can load and visualize these files through the Data Visualization tab. It is possible to modify the created particle concentration file. When Compute Spatial Particle Distribution (*.num) is selected, the following options are enabled:
Gaussian Blur Radius / (Voxel): Choose a voxel number larger than 0 to blur the particle distribution fields with a Gaussian kernel of the given size.
Ignore Inactive Particles: Check this option to ignore particles not moving anymore in the particle distribution field.
Normalize Field: Check this option to normalize the mean of the particle distribution field to the inflow concentration.
If the Compute Average Displacement box is checked, the Travel displacement column is shown additionally in the report, and a Travel Displacement curve is added to the Plots subtab.
Check Use Adsorption Time and define an adsorption time for each solid or porous material to consider short-time adsorption in the Travel Displacement curve. This option has no effect on the Travel Displacement values shown in the tables under the Report subtab but will influence the calculation of particle diffusivities. On the Plots subtab, two Travel Displacement curves, with and without adsorption are plotted.
To evaluate residence times in the different materials, check Compute Collision Statistics and Residence Times. The table Particle residence time statistics in the Report subtab is created with columns showing the percentage of particles with specific residence times in each of the materials. Additionally, a Residence time plot is created on the Plots subtab.
The Particle collision statistics table is shown below the Particle residence time statistics table. It shows the mean residence time of particles for each material, together with the mean number of collisions with this material, the mean number of entries to this material, and the percentage of particles trapped in this material. In the example shown here, the mean value of particle collisions with the solid material with material ID 1 is 3569.49. Since it is a solid material, particles cannot enter the material and the residence time in this material is 0. For the porous material with ID 2, a reflection probability was defined for the particles. Due to this reflection probability, particles can enter the material, or are reflected at the boundary. The mean value for residence time, collisions and entries are non-zero. Dependent on the collision model with solid or porous material, particles can also be trapped in a material. If this is the case, the percentage of trapped particles is reported in the last column of the table.
To compute chemical reactions of the first order based on the residence times in the different materials, check Compute Chemical Reaction in the left panel and enter a Reaction rate constant for each pore or porous material. Dependent on the reaction rate constant and the residence time of the particles in a material, the residual of each particle species is computed based on the formula described in the theoretical background.
The table Reaction Statistics is created on the Report subtab, and a Reaction Statistics plot on the Plots subtab. Both contain the histogram data with the relative particle count for specific residuals of the particles. In the example shown here, for nearly 30% of the particles, only up to 2% remain that have not reacted yet.
Compute Spatial Particle Distribution (*.num)