Vignesh Sitaraman
3edbfa5bd8
modified: anasen_fem/clean.sh new file: anasen_fem/dotproduct.py new file: anasen_fem/paraview_dotproduct.py modified: anasen_fem/paraview_plotter.py modified: anasen_fem/run.py modified: anasen_fem/scalars.dat.names new file: anasen_fem/scalars_weight.dat new file: anasen_fem/scalars_weight.dat.names modified: anasen_fem/wires2d.sif new file: anasen_fem/wires2d_weight.sif modified: anasen_fem/wires_gmsh2d_bc.py
47 lines
3.6 KiB
Markdown
Executable File
47 lines
3.6 KiB
Markdown
Executable File
### README for ANASEN fem simulations:
|
|
|
|
* There are a few iterations of these simulations that already exist. Be sure to also locate and refer to them if necessary.
|
|
* Install gmsh and its python api by running (Ubuntu 22.04 LTS)
|
|
|
|
```
|
|
sudo apt install gmsh python3-gmsh
|
|
```
|
|
|
|
* Gmsh gives us the tools to create a meshgrid that samples the 2d space appropriately to plot the field/equipotential lines.
|
|
* The output file typically has the .msh extension. This is read as input to Elmer, which is the FEM differential-equation solver.
|
|
|
|
* Install Elmer via the following steps:
|
|
|
|
```
|
|
sudo add-apt-repository ppa:elmer-csc-ubuntu/elmer-csc-ppa
|
|
sudo apt install elmerfem-csc-eg
|
|
```
|
|
|
|
* Install ParaView for visualizations by downloading from the Linux .tar.gz link at https://www.paraview.org/download/
|
|
- The current version is tested to work on Paraview 6.1.0. The default version in Ubuntu 22.04 repositories has some trouble with scripting
|
|
* v0.0.1, March 10 2026
|
|
- 2d simulations of fields only. gmsh for meshing, elmer for fem, paraview to plot
|
|
- Before running, open `paraview_plotter.py` to make the bash shebang (#!) point to the location of `pvpython` or `pvbatch`
|
|
- `python3 run.py` should run everything in order, and is hopefully all the files are self-documenting
|
|
* v0.0.2, September 2026
|
|
- Adds the Ramo weighting field and the `E . E_w` dot product for one cathode wire.
|
|
- `wires_gmsh2d_bc.py` now cuts the wires into the gas disk with `occ.fragment` instead of `mesh.embed`, so each wire boundary is a real edge of the domain. One cathode (optional 2nd argument, default 1) gets its own physical group, **tag 40**; the other 23 stay in tag 30.
|
|
- Two solves, same mesh, identical apart from the potentials:
|
|
|
|
| file | tag 40 | output |
|
|
|---|---|---|
|
|
| `wires2d.sif` | 0 V, like every other cathode | `wires2d/elfield_anasen_t0001.vtu` |
|
|
| `wires2d_weight.sif` | 1 V, all else 0 V | `wires2d/elfield_weight_t0001.vtu` |
|
|
|
|
- `dotproduct.py` reads both and writes `wires2d/dotproduct.vtu` with `DotProduct = E . E_w` (V/m^2). It aborts if the node sets differ or if either field is all zeros — both are silent failures otherwise.
|
|
- `paraview_dotproduct.py` renders it. `DOT_MIN`/`DOT_MAX` set the colour range and decide whether the picture shows anything.
|
|
- `paraview_plotter.py` gains two views: the equipotentials over one quadrant, and streamlines over the same quadrant. Streamlines are drift paths up to diffusion, so they show which wire collects charge from where; `SEED_POTENTIAL` and `SEED_STRIDE` control them.
|
|
- Six PNGs per z-locus, archived as before (`<Stem>_z_<count>_<z>[_quarter].png`). `Field_ouput` keeps its typo so the new files sort with the dozen already in `png/`.
|
|
- `STAGE` in `run.py`: `1` = mesh + physical solve, `2` = weighting solve + dot product reusing stage 1's mesh, `0` = both. Stage 2 never re-meshes, so it applies to whichever z stage 1 ran last.
|
|
- **Do not pass `-autoclean` to ElmerGrid.** It renumbers the physical groups (13/10/20/30/40 become 1/4/5/6/7), so every `Target Bodies`/`Target Boundaries` in the sifs matches nothing, Elmer solves nothing, and the potential comes out identically zero with no error.
|
|
- `mesh.recombine()` and `mesh.refine()` are both off: recombination ran over half an hour on the barrel surface without finishing, and refine took the mesh to ~16M nodes.
|
|
- Note on the solver stack: both sifs are the same file bar the potentials, so whatever `FluxSolver` does to `Electric Field` it does equally to both and the dot product stays consistent.
|
|
* v0.0.3, planned TODO
|
|
- Garfield to take Elmer results and perform charge-transport
|
|
- Sweep the weighting solve over all 24 cathodes rather than one at a time
|