PHARE load estimator

Estimate memory and CPU load for a global magnetosphere PIC run with PHARE, comparing an AMR hierarchy (any number of levels) to a uniform reference run.

Domain (user convention)

-x points toward the Sun. Default domain: x ∈ [-30, +150] Re, y, z ∈ [-30, +30] Re. Internally the Shue (MP) and Jelínek (BS) models are evaluated in standard GSE (+x sunward); coordinates are mirrored on the plot.

Configuration

Everything is driven by a TOML config file (see config.toml). You can:

• add, remove, or rename levels
• change resolutions (in km, the delta_i_km field sets the ionic unit)
• pick each level's region: "full" (whole domain), "shell" with pad_re (sheath ±pad), or "band" with band_re (band around MP and BS)
• toggle dayside-only PIC
• change the solar-wind parameters and the domain box
• change the run target, particle cost model, and the reference uniform dx

Run with the bundled config:

.venv/bin/python -m phare_load.cli

Or with your own:

.venv/bin/python -m phare_load.cli --config my_setup.toml --out my_plot.png

Interactive web app (no install)

A browser version of the estimator (Streamlit + Pyodide, via stlite) lives in docs/ and is served by GitHub Pages at:

https://pharehub.github.io/pharculator/

It runs entirely client-side — Python executes in your browser via WebAssembly, no server is needed. First load is ~30 MB (numpy, scipy, scikit-image, plotly, Streamlit runtime), cached for subsequent visits.

To enable / re-enable GitHub Pages on this repository: Settings → Pages → Source = Deploy from a branch, Branch = main, Folder = /docs.

After changing anything in src/phare_load/, sync the copy used by the web app:

bash docs/sync_source.sh

To preview the web app locally without deploying:

cd docs && python -m http.server 8000
# open http://localhost:8000/

3D visualization (optional)

Install the extra deps once:

.venv/bin/pip install -e ".[viz3d]"

Then add --plot3d to produce a standalone interactive HTML alongside the 2D figure:

.venv/bin/python -m phare_load.cli --plot3d

This writes outputs/load_estimate_3d.html — open it in any browser to rotate the nested PIC shells, the Shue magnetopause, and the Jelínek bow shock around Earth. The default view is a Y < 0 cutaway so the nested L1→Lₙ onion is exposed; pass --no-cutaway to render full surfaces.

For static slide-friendly PNGs, append one or more camera presets (front, oblique, tail, top):

.venv/bin/python -m phare_load.cli --plot3d \
  --plot3d-png oblique --plot3d-png front

Each PNG is saved next to the HTML as load_estimate_3d_<preset>.png.

Tests

.venv/bin/pytest

Models

• Magnetopause: Shue et al. 1998.
• Bow shock: Jelínek et al. 2012 (paraboloid form).

The MP/BS surfaces flare unphysically deep into the tail; the dayside-only flag is on by default to keep PIC where the fits are reliable.

Subcycling

Each coarser AMR level uses dt_ratio_per_level × the dt of the next finer level (default 4, i.e. dt ∝ dx²). The finest level shares its dt with the uniform reference, so timestep counts are directly comparable.