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Gaussian Pulse: M1 RK1 and FLD backward Euler

Saved-state movies

Movies use stored numerical states, held without solution interpolation.

M1 reference: linearized analytic reference. Fourier telegraph-equation reference for isotropic, linearized radiation moments. Nonlinear M1 can retain a closure-model error at finite amplitude.

FLD reference: periodic constant-diffusion analytic reference. Each retained Fourier mode decays as exp[-D |k|² t], with D = c/(3χ) and reference flux -D grad(E). It uses the same filtered initial energy as the M1 run, while M1 has its separate telegraph reference. This is an analytic diffusion-limit reference, not an exact solution of nonlinear flux-limited diffusion.

M1 and FLD solve different transport closures. Both updates are first order in time. A small model discrepancy does not establish accuracy against an exact solution. M1 evolves radiation flux; FLD reconstructs diagnostic flux from its energy gradient. Flux differences are not errors in a shared radiation-momentum conservation law. FLD here supports stationary ideal gas with physical light speed on the CPU.

Level 0

M1 RK1: complete results, parameters and reference discussion

FLD backward Euler: complete results, parameters and reference discussion

matched. No other refinement level or physical time is substituted for a missing partner.

Level 0 model profiles and separately applicable references

Matched profile coordinates and values (CSV)

FLD minus M1: model discrepancy on the saved slice

FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^32.203675e-055.805825e-052.261711e-04
Radiation flux xerg/(cm^2 s)2.828845e+055.418360e+051.800545e+06
Radiation flux yerg/(cm^2 s)2.828845e+055.418360e+051.800545e+06
Radiation flux zerg/(cm^2 s)1.877343e+054.736037e+051.800545e+06

M1 RK1: model-specific reference diagnostics

linearized analytic reference. Fourier telegraph-equation reference for isotropic, linearized radiation moments. Nonlinear M1 can retain a closure-model error at finite amplitude.

Area-weighted reference errors on this model’s original leaf slice.

FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^35.724338e-051.415729e-045.451648e-04
Radiation flux xerg/(cm^2 s)9.345218e+052.020099e+067.169529e+06
Radiation flux yerg/(cm^2 s)9.345218e+052.020099e+067.169529e+06
Radiation flux zerg/(cm^2 s)5.657127e+051.813816e+067.169529e+06
Solver-reported full-volume reference norms
FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^32.077154e-057.295665e-055.451648e-04
Radiation flux xerg/(cm^2 s)2.754654e+051.018561e+067.169529e+06
Radiation flux yerg/(cm^2 s)2.754654e+051.018561e+067.169529e+06
Radiation flux zerg/(cm^2 s)2.754654e+051.018561e+067.169529e+06

Source slice CSV · Run metadata

FLD backward Euler: model-specific reference diagnostics

periodic constant-diffusion analytic reference. Each retained Fourier mode decays as exp[-D |k|² t], with D = c/(3χ) and reference flux -D grad(E). It uses the same filtered initial energy as the M1 run, while M1 has its separate telegraph reference. This is an analytic diffusion-limit reference, not an exact solution of nonlinear flux-limited diffusion.

Area-weighted reference errors on this model’s original leaf slice.

FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^32.312297e-055.064725e-051.861876e-04
Radiation flux xerg/(cm^2 s)2.092399e+053.542431e+058.783358e+05
Radiation flux yerg/(cm^2 s)2.092399e+053.542431e+058.783358e+05
Radiation flux zerg/(cm^2 s)1.601308e+053.261437e+058.783358e+05

Source slice CSV · Run metadata

Model discrepancy and input hashes (JSON)

Level 1

M1 RK1: complete results, parameters and reference discussion

FLD backward Euler: complete results, parameters and reference discussion

matched. No other refinement level or physical time is substituted for a missing partner.

Level 1 model profiles and separately applicable references

Matched profile coordinates and values (CSV)

FLD minus M1: model discrepancy on the saved slice

FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^34.032591e-058.036957e-052.775694e-04
Radiation flux xerg/(cm^2 s)5.839559e+051.340777e+067.581579e+06
Radiation flux yerg/(cm^2 s)5.839559e+051.340777e+067.581579e+06
Radiation flux zerg/(cm^2 s)1.188700e+052.375642e+051.235064e+06

M1 RK1: model-specific reference diagnostics

linearized analytic reference. Fourier telegraph-equation reference for isotropic, linearized radiation moments. Nonlinear M1 can retain a closure-model error at finite amplitude.

Area-weighted reference errors on this model’s original leaf slice.

FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^32.482571e-057.264041e-053.228860e-04
Radiation flux xerg/(cm^2 s)4.062469e+051.379910e+067.285653e+06
Radiation flux yerg/(cm^2 s)4.062469e+051.379910e+067.285653e+06
Radiation flux zerg/(cm^2 s)3.593163e+051.235110e+067.285653e+06
Solver-reported full-volume reference norms
FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^37.580997e-063.345063e-053.228860e-04
Radiation flux xerg/(cm^2 s)9.243889e+045.521543e+057.285653e+06
Radiation flux yerg/(cm^2 s)9.243889e+045.521543e+057.285653e+06
Radiation flux zerg/(cm^2 s)9.243889e+045.521543e+057.285653e+06

Source slice CSV · Run metadata

FLD backward Euler: model-specific reference diagnostics

periodic constant-diffusion analytic reference. Each retained Fourier mode decays as exp[-D |k|² t], with D = c/(3χ) and reference flux -D grad(E). It uses the same filtered initial energy as the M1 run, while M1 has its separate telegraph reference. This is an analytic diffusion-limit reference, not an exact solution of nonlinear flux-limited diffusion.

Area-weighted reference errors on this model’s original leaf slice.

FieldUnitsL₁L₂L∞
Radiation energy densityerg/cm^31.089667e-053.629176e-052.444300e-04
Radiation flux xerg/(cm^2 s)7.780558e+041.604165e+058.617109e+05
Radiation flux yerg/(cm^2 s)7.780558e+041.604165e+058.617109e+05
Radiation flux zerg/(cm^2 s)3.036714e+048.303923e+045.479825e+05

Source slice CSV · Run metadata

Model discrepancy and input hashes (JSON)

How these comparisons are measured

All field values retain their saved units. Central profiles share x coordinates and the positive row adjacent to y = z = 0. Adaptive leaf-cell averages are prolonged as constants onto the finest common Cartesian x-y partition, without extrapolation or time interpolation. Different leaf sizes may average different z extents adjacent to the plane. These are saved finite-volume slices.

Slice L₁ is mean absolute discrepancy, L₂ is root-mean-square discrepancy, and L∞ is maximum absolute discrepancy, with area weighting. These are two-dimensional diagnostics; separately labeled solver reference norms cover the full volume. Each model is measured against its own saved reference. A diffusion-limit error includes departures of the nonlinear closure from that limit.