M1 RK1 and FLD: model comparisons
All eight problems compare both closures at the same refinement level and physical time. Partial pairs remain visible while their partner is pending. References are attached to the model they describe.
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 uses physical light speed on the CPU. Moving cases include gas transport and radiation force/work; their derived lab-frame flux includes radiation enthalpy advection.
| Problem | Available reference | Comparison status |
|---|---|---|
| Streaming Wave | free-streaming analytic profile (M1); no supplied FLD spatial analytic reference (FLD) | L2: matched; L3: matched; L4: pending |
| Streaming Front | free-streaming analytic profile (M1); no supplied FLD spatial analytic reference (FLD) | L2: matched; L3: awaiting matching method; L4: pending |
| Gaussian Pulse | linearized analytic reference (M1); periodic constant-diffusion analytic reference (FLD limit) | L2: matched; L3: pending; L4: pending |
| Equilibrium Sphere | diffusion-limit analytic reference (M1); steady Gaussian-emitter diffusion-limit analytic reference (FLD limit) | L2: matched; L3: pending; L4: pending |
| Subcritical Shock | no supplied analytic or digitized numerical profile (M1); no supplied independent reference profile (FLD) | L2: matched; L3: pending; L4: pending |
| Supercritical Shock | no supplied analytic or digitized numerical profile (M1); no supplied independent reference profile (FLD) | L2: matched; L3: pending; L4: pending |
| Radiating Blast | no supplied analytic or digitized numerical profile (M1); no supplied independent reference profile (FLD) | L2: matched; L3: pending; L4: pending |
| Marshak | Su–Olson diffusion reference (M1); Su–Olson linear diffusion analytic reference (FLD limit) | L2: matched; L3: pending; L4: pending |