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Basic functionality and features (GeoDict Base Package) / Re: Visualization Questions

« on: June 05, 2023, 11:48:38 AM »

Hello Aaron,

it's possible to set these visualizations. Let me answer your question assuming that you simulated the flow through the pores of a porous structure (see image 1).
[attachimg=1]

1.) To show a volume field in 2D view, load the “velocity” volume field. Then click on 2D view and in the camera tab, select Grid: “Structure Outlines” in the combobox. Now you see an outline of the structure, as shown in image 2.
It's now possible to modify the view:  For example, you can deselect the structure by unchecking “Structure” in the corresponding tab in the visualization settings.

To enhance the outlines, you can set the volume field to transparent. Check the “Transparent” checkbox (image 3), with the “Edit …” color map you can select the transparency that you prefer. The outlines are one pixel by default and appear quite slim. As one solution, you can either zoom out to show the whole structure smaller on the screen so that the lines will appear thicker in comparison to the structure size.

For a more controlled way, go to File --> Save Image as --> Select “Legend Placement: Attached”, uncheck “Automatic Resolution” and set Zoom Factor e.g. to “2”. Then, one voxel will be shown by 2x2 pixels and therefore the outline is half as thick as one voxel (image 4).

You can further play with Camera --> Depth Settings or add more points in the transparency of the volume field (e.g. setting the transparency of the volume field to 0 for velocities close to 0) as shown in images 5-6.

[attachimg=2]

2.) Streamlines in 3D view do not project on 2D view. Instead, to show the volume field lines in 2D view (e.g. the flow field lines) select “Schlieren” (image 8) and then the x position, where you want to show the projection of the flow. 
Now you can increase the resolution (e.g. to 4) and select “Colorize".
Another way to show the structure is by selecting the clipping in X direction accordingly (see image 9).

Afterwards, you could fine-tune the 2D angle in the “Camera” tab and deselect the bounding box in the Visualization side bar -> Legends / Overlays -> Uncheck Bounding Box. (Image 10) 

[attachimg=3]
[attachimg=4]

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Digital Battery Development / Re: [GeoDict 2023] How can I simulate charge rate dependent capacities?

« on: May 19, 2023, 01:22:36 PM »

Let me pleaseanswer to this issue to show you how you can easily reflect the effect of different charging rates on the cell capacity in BatteryDict in GeoDict 2023.

The reached capacity during cell cycling is often defined by upper/lower cell voltages  in real experiments. These upper/lower cell voltages are reached during the discharge/charge of a cell. The limitation of cell voltages prevents damage of a cell, e.g. by lithium plating at very low cell voltages or electrolyte decomposition at very high cell voltages.
In GeoDict 2023, the cut-off voltages can be provided as a boundary condition to stop a constant current charging simulation.

As an example, let us consider the delithiation of a NMC622 cathode vs a lithium reservoir using the "Charge Half Cell" functionality of BatteryDict. The cell potential of the half cell will increase during delithiation of the NMC622, i.e. we want to provide an upper cut-off voltage to stop the simulation. This can be done in the "Experiment" tab in the Edit parameters window of charge half cell. Please toggle the checkbox at "Use Upper Cut-Off Voltage" and enter the desired cut-off voltage. With the settings provided below the simulation will stop either when the upper cut-off voltage of 4.3 V is reached or when the final Electrode SOC of 5% is reached.
[attachimg=1]

You will see the effect when performing charging simulations with different C-rates: if you use higher C-rates/currents, the cut-off voltage might be reached at less transferred capacities. In the example, the cut-off potential of 4.3V was reached after a transferred charge of 0.423 µAh with the lowest current (2C), while larger currents reached the cut-off potential already after a transferred charge of 0.417 µAh (3C) and 0.402 µAh (4C).
[attachimg=2]

For further details regarding the cut-off voltage settings, please refer to the current BatteryDict User Guide.

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Digital Battery Development / Re: Regarding the calculation method of the thickness distribution

« on: January 20, 2023, 03:03:00 PM »

Dear Daisuke,

thank you for your question. We would propose the following workflow to estimate the shell thickness:
Assume you have core-shell particles of a base material (MaterialID 01) and a shell material (MaterialID 02). Then we propose the following workflow:

• Reassign the base material to a liquid material. The example structure may now look as in the following picture.
  [attachimg=1]
• Use "Analyze -> Grain Find -> Estimate Grain Diamters" to estimate the coating thickness.
  
  • “Estimate Grain Diameters” uses internally the Euclidian Distance Map, a watershed algorithm is used to transfer the values of voxels with small components to neighboring voxels with large components
  • We have a technical paper available that describes the background of the “Estimate Grain Diameters” algorithm: https://www.math2market.de/fileadmin/Showroom/Technical-Reports/M2M-2021-01_TechReport_Math2Market.pdf
  • In the example, I used the options “Chosen Material IDs: 2” (coating’s material ID) and “Remove Grain Fragments at Domain Boundary” (if you leave this checked you will get low coating thickness at the domain boundaries in the result
  • [attachimg=2]

Finally, you can interpretate the grain diameters as the shell thickness. It can be visualized by the volume field "Diameter".
[attachimg=3]

Note: You could use a similar workflow with Analyse -> MatDict -> Material Characterization -> Solid Size Distribution (Granulometry) in the step 2 from above.

• Please note the instruction for Granulometry in the MatDict UserGuide (page 20 and following).
• Especially the bin size must be selected small enough depending on the expected minimum coating thicknesses.
• Different visualization options are described, probably the best for your problem is the volume fraction visualization.

This approach will also fit spheres in the coating material, however corners are a differently treated as in the "Estimate Grain Diameter" approach from above, because smaller spheres are not merged with neighboring large spheres.

I hope my answer helped you.

Best regards, Roman