V-BO-02 — PMMA-on-Kaowool burnout on a fixed mesh under surface absorption (top-cell parking)

Tags: eulerian, burnout, depletion, surface_absorption, coupled

References:

MaCFP-2 PMMA gasification case (NIST), 50 kW/m²

Problem statement

The V-BO-01 deck on a fixed mesh, with the incident flux absorbed at the surface. A fixed mesh keeps every cell's volume, so a gasifying cell empties instead of thinning, and only the top live cell parks: once its condensed concentration falls below 5 % of its initial value it merges into the cell beneath, which becomes the surface. With the flux absorbed at the surface, the surface cell is the hottest and empties first, so the layer burns top down and no cell below the surface empties before it.

The run must park all 60 PMMA cells, lose exactly the mass of the PMMA layer, end on the bare substrate, close the mass ledger, keep the maximum live-cell temperature below 1000 K, and take no step below the post-park reset. The peak mass loss rate is informational: surface absorption is a different problem from the in-depth reference of V-BO-01.

Quantities of interest (n = 120)

QoI	value	exact	error	tolerance	within tol	provenance
complete burnout: live thickness at t_end is the substrate	0.012	0.012	3.333e-06	1e-05	yes	every PMMA cell parked; 12.00 ± 0.01 mm
mass loss of the gasified PMMA layer	69.92	69.91	0.005843	0.3	yes	percent of the initial mass; exact = ρPMMA LPMMA / m₀
peak MLR	24.25	24.61	0.01478	0.25	yes	g m⁻² s⁻¹; surface absorption on a fixed mesh, a different problem from the in-depth reference (informational)
mass ledger closure	0.0008933	0	0.0008933	0.001	yes	total-mass drop vs ∫ ṁ″ dt over the run
surface-Newton warnings	0	0	0	0.5	yes	boundary temperature solve converged at every evaluation
park events	120	120	0	0.5	yes	every PMMA cell parks as the top live cell, top down
maximum live-cell temperature	917	—	917	1000	yes	K over every accepted step (observed 915); the surface cell is the hottest and empties first, so no interior void forms
smallest accepted step	1e-06	1e-06	2.525e-09	0.001	yes	s; no step below the post-park reset (observed 1e-6 s)
Newton failures	102	0	102	100	no	budget at the CI resolution (60 PMMA cells); observed 56, about one per park interval
accepted steps	4198	0	4198	2000	no	budget at the CI resolution (60 PMMA cells); observed 1572, about 26 per park interval

V-BO-02 mlr_history

V-BO-02 thickness_history

V-BO-02 max_temperature_history

Solver configuration

setting	value
integrator	KenCarp4 (default)
use_ale	false
handle_depletion	true
depletion_threshold	0.05
min_cells	2
radiation_model	SURFACE_ABSORPTION
abstol	1.0e-8
reltol	1.0e-6