Nonlinear Heat — Radiative BCs T^4 (dim=40)

PARITYS2 · dim 40

No clear winner. The survival gap is under 10 percentage points and the balanced-score gap is under 0.05, so neither SolvSRK nor the best baseline clears the win threshold. Either works — choose on cost, licensing, or integration effort. All verdicts →

Two-layer heat conduction with Stefan-Boltzmann radiative boundary conditions. Left face exchanges radiation with 500 K source, right face with 300 K ambient. The T^4 nonlinearity in the BCs makes the effective system matrix state-dependent. LRDE-ineligible. Tests boundary of LRDE applicability with realistic radiative coupling.

Thermal & heat transfer

Problem definition

Incropera & DeWitt, Fundamentals of Heat Transfer, 7th ed.; Siegel & Howell, Thermal Radiation Heat Transfer, 6th ed.

Canonical RHS excerpt from the registered callable used for this benchmark cell. Expand it to verify the state equations; it is not a standalone runnable fixture.

Show canonical RHS excerpt
def rhs(t: float, temp: np.ndarray) -> np.ndarray:
    temp = np.clip(np.asarray(temp, dtype=float), 200.0, 3500.0)
    d = np.zeros(n)
    for i in range(n):
        t_left = temp[i - 1] if i > 0 else temp[i]
        t_right = temp[i + 1] if i < n - 1 else temp[i]
        d[i] = alphas[i] * (t_left - 2.0 * temp[i] + t_right) / dx2

    # radiative BCs: left face exchanges with 500 K source, right with ambient
    q_rad_left = emissivity * stefan_boltzmann * (500.0**4 - temp[0]**4)
    q_rad_right = emissivity * stefan_boltzmann * (t_ambient**4 - temp[-1]**4)
    d[0] += q_rad_left / (rho_c * dx)
    d[-1] += q_rad_right / (rho_c * dx)
    return d
Parameters
  • alphas = [0.0001, 0.0001, 0.0001, 0.0001, 0.0001, 0.0001, …] [shape=(40,), min=1e-06, max=0.0001]
  • dx = 0.00025
  • dx2 = 6.25e-08
  • emissivity = 0.85
  • n = 40
  • rho_c = 3.5e+06
  • stefan_boltzmann = 5.67037e-08
  • t_ambient = 300
Initial condition
y(0) = [400, 397.435897436, 394.871794872, 392.307692308, 389.743589744, 387.179487179, …] [shape=(40,), min=300, max=400]
Horizon
t ∈ [0, 20]

Canonical RHS excerpt captured from the same registered callable used for the published benchmark. Frozen closure values are summarized below; helper imports and solver settings are intentionally omitted.

Fingerprint

Spread: extreme

Default noise: none

Recommendation snapshot

Clean best: SolvSRK

Noisy best: SolvSRK

Coverage

14 solver arms · clean + 5 noise levels

Ranked on survival, precision, and speed

Versions & freeze

Methodology →
Freeze
2026-08-13
libsolvsrk
2.3.0
SciPy
1.14
SUNDIALS
CVODE (bundled backend)

20 seeds/cell default · 14 arms · TRL 4–5 · simulation-lab validated · this page: Nonlinear Heat — Radiative BCs T^4 (dim=40) (nonlinear-heat-radiative-bcs-t-4-dim-40)

Governed SolvTune benchmark freeze; per-arm medians only. RHS definitions and raw trial rows are not published.

Self-reported by Resonix Labs · not independently verified

Results matrix

Pick an objective and a noise level to rank all arms on survival, median SCD, median nfev, and median wall time. Medians across seeds.

Objective

Best overall trade-off of survival, precision, and speed.

Noise level

#SolverSurvivalSCDnfevWallScore
1SolvSRK
100%
11.42,03266 ms0.890
2SciPy RadauSciPy
100%
10.61,23139 ms0.871
3Tsit5external
100%
8.5276,97821.15 s0.822
4SciPy LSODASciPy
100%
8.41,43422 ms0.818
5SciPy RK45SciPy
100%
8.3269,0245.55 s0.818
6SciPy DOP853SciPy
100%
8.3238,9704.45 s0.817
7SciPy BDFSciPy
100%
8.156220 ms0.813
8CVODE Adamsexternal
100%
8.02,83955 ms0.810
9CVODE BDFexternal
100%
8.049913 ms0.810
10SciPy RK23SciPy
100%
7.6152,0122.88 s0.799

At Clean, best balanced arm is SolvSRK.

Values are medians across seeds, measured by Resonix Labs on Resonix hardware and not independently verified; nfev and wall are on reference lab hardware (indicative). Under injected noise only SolvSRK and the SciPy arms are run. How we measure accuracy → · Verification status →

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Cite this page

Replace the access date. Pin the freeze ID and library versions when comparing against a later export. Cite it as what it is — a self-reported vendor benchmark, not an independently verified result. The note field says so; please keep it.

@misc{resonix_evidence_nonlinear_heat_radiative_bcs_t_4_dim_40_2026,
  title        = {Resonix Evidence Portal: Nonlinear Heat — Radiative BCs T^4 (dim=40)},
  author       = {{Resonix Labs (Canada) Inc.}},
  year         = {2026},
  howpublished = {\url{https://resonix.tech/evidence/problems/nonlinear-heat-radiative-bcs-t-4-dim-40}},
  note         = {Self-reported vendor benchmark; internally generated by Resonix Labs and not independently verified. Accessed YYYY-MM-DD. Freeze 2026-08-13; libsolvsrk 2.3.0; SciPy 1.14.}
}

Related

TRL 4–5 · simulation-lab validated · 398 problems · 14 solver arms · clean + 5 noise levels

Freeze: 2026-08-13 · scipy 1.14 · libsolvsrk 2.3.0 · Methodology

Self-reported by Resonix Labs · not independently verified · Verification status