A model for the oxidative pyrolysis

[Maryam Javid Nejad]

 Hi guys,

I had issue when I tried to reproduce the simulation under air environment (0.77 n2 and .23 O2) in the paper: 'A model for the oxidative pyrolysis of wood', Lautenberger, Fernandez-Pello, 2009.  https://www.sciencedirect.com/science/article/pii/S0010218009000832. When I run the model using Gpyro 0.82 and .8186, first time steps reduce significantly to get Yj converge and after around 300s Yj will jump to 10 and the run stops. The simulation works under revision 0.7.

I attached input file and error. Could you please advise me if there is any way to get current revision to work possibly with changing relaxation parameters (as I guess that creates diverge) or whatever to solve issue.

Model 11 (under air atmosphere - Chris paper's simulation)

Cheers,

[Juan Hidalgo Medina]

Dear Gpyro gurus at Imperial College,

At UQ we have been trying to use the latest version of Gpyro (https://github.com/reaxfire/gpyro) to model the case simulated by Lautenberger and Fernandez-Pello (https://doi.org/10.1016/j.combustflame.2009.04.001).

We are experiencing issues in convergence for gas species Yj. We attempted to address these issues by:

- Modifying the YJTOL parameter (line 858 in gpyro_io.f90) to a lower value (e.g. 1E-2 or 1E-3).

- Modifying the threshold imposed to YJSUM (line 4207 in gpyro_pyro.f90) to a narrower window (e.g. 0.99 to 1.01).

However, the issue remains.

The convergence issue disappears when the mass transfer coefficient at the surface boundary condition (hm=0), however, doing this disables the oxidation reaction as oxygen is not transferred to the solid.

We are wondering if anyone has any ideas for what could be causing this convergence issue. When running the model in an older version of Gpyro (i.e. 0.7), the convergence issue does not occur.

Any thoughts would be much appreciated.

Best regards,

Juan Hidalgo