# strip_hole_current

Family 13: direct current in a flat busbar with a round hole (a bolt hole), possibly off the centre line.

How much the hole adds to the resistance and how much it crowds the current, the two numbers a busbar designer needs.
Hand anchor for a small hole in a wide strip: the extra resistance equals extra strip length pi d^2 / (2 W) (Maxwell's
dilute limit), and the current density at the hole's side reaches twice the local value. Half the strip is solved along
the length (the mid plane is at half voltage); the far end is long enough for the current to be uniform again.

## Parameters (nondimensional)

| parameter | range |
|---|---|
| `d_over_W` | 0.05 - 0.6 |
| `e_over_W` | 0.0 - 0.15 |

## Answers and their error bands

| answer | error band (median / 95 % / max) | similarity x2 / x4 | CalculiX (same mesh) |
|---|---|---|---|
| `dl_over_W` | 0.0086 % / 0.47 % / 0.47 % | max 0.0013 % | max - |
| `kj` | 0.19 % / 1.4 % / 1.4 % | max 0.13 % | max - |

## Checks

- points: 200 solved, 0 failed
- three-mesh studies: 40 (every 5th point); the band of each point is 1.25 x the largest standard-mesh error among its 3 nearest studies
- symmetry check (max): 0 %
- neighbour check: flagged 1, re-solved on a finer mesh 2, unresolved 0
- direction checks: dl_over_W vs d_over_W ok (rho 1.0)

## Against hand theory

| ratio | median | 95 % | max |
|---|---|---|---|
| `dl_over_maxwell` | 1.1 | 1.397 | 1.542 |

## Columns of points.csv

parameters, the answers, `<answer>_band` (relative), the hand-theory ratios, `mirror_err`, `equilibrium_err` (where a single reaction exists), `<answer>_loo_err` / `_neighbour_flag` (leave-one-out prediction from all other points), `<answer>_recheck_diff` / `_flag_resolved` (finer re-solve of a flagged point), `has_gci` / `has_similarity` / `has_calculix`, `nodes`, `solve_s`, `studio` (version).

Solved with NovaSolver Studio through the same commands an AI client uses over MCP; the first section says which solver and mesh. The claim is verification (the equations are solved within the band), not validation against tests.

## License

This data is licensed under CC BY 4.0: https://creativecommons.org/licenses/by/4.0/
Credit: NovaSolver, https://novasolver.jp/studio/verified/
Provided as is, without warranty. Design decisions remain the user's responsibility.