fix: improve finite difference method logic for cases where r_i is no…

[BramVloedgraven]

…t centered between neighbours r_{i-1} and r_{i+1}.

[Copilot]

Pull request overview

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This PR updates the finite-difference discretization to better handle non-centered radii grids, and refreshes the associated validation artifacts.

Changes:

• Rename internal interstitial radii storage to _inter_radii_grid and update dependent call sites.
• Rework surface-area grid construction and the second-derivative finite-difference factor to align with the new discretization.
• Update unit tests and refresh golden CSV temperature-solution outputs to match the new numerical results.

Reviewed changes

Copilot reviewed 133 out of 133 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/cable/test_cable.py	Updates surface-area grid test to use the new instance-based construction and boundary definition.
cable_thermal_model/model/cables/cable.py	Renames interstitial radii field, changes surface-area grid construction, and updates the second-derivative common factor.
cable_thermal_model/model/cables/cable_air.py	Updates references to the renamed _inter_radii_grid field in boundary-condition assembly.
cable_thermal_model/model/cables/cable_trefoil_circuit_single_pipe.py	Updates _calculate_inter_rhos call to use _inter_radii_grid.
cable_thermal_model/validation/cable_analysis.py	Updates validation heat-flow computation to use _inter_radii_grid.
test_results/test_compute_temperature_solution/y_y_y_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_y_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_y_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_top.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_y_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_top.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_y_n_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_y_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_y_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_y_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_n_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_n_y_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_n_y_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_n_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_n_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/y_n_n_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_y_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_y_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_y_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_y_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_n_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_n_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_n_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_y_n_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_y_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_y_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_y_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_y_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_y_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_n_y_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_n_y_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_n_n_y_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_n_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_right.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_n_n_n_YMeKrvaslqwd12_20kV1x630Alrm+as50_c1_trefoil_left.csv	Update expected temperature solution snapshot after discretization change.
test_results/test_compute_temperature_solution/n_n_n_n_n_GPLK10_10kV3x185Al_c1_single.csv	Update expected temperature solution snapshot after discretization change.

Comments suppressed due to low confidence (1)

tests/cable/test_cable.py:1

• The test currently calls the instance method via the class (Cable._construct_surface_area_grid(DummyCable(...))). While this works, it’s non-idiomatic and makes it easier to miss issues if the method is overridden. Prefer calling it as an instance method on the dummy instance (e.g., DummyCable(radii_grid)._construct_surface_area_grid()) to better reflect real usage.

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