Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Propagation of symmetric and non-symmetric lean hydrogen flames in
  narrow channels: influence of heat losses   In this paper we present results of direct numerical simulations of lean
hydrogen/air flames freely propagating in a planar narrow channel with varying
flow rate, using detailed chemistry and transport and including heat losses
through the channel walls. Our simulations show that double solutions,
symmetric and non symmetric, can coexist for a given set of parameters. The
symmetric solutions are calculated imposing symmetric boundary conditions in
the channel mid plane and when this restriction is relaxed non symmetric
solutions can develop. This indicates that the symmetric solutions are unstable
to non symmetric perturbations, as predicted before within the context of a
thermo diffusive model and simplified chemistry. It is also found that for lean
hydrogen/air mixtures an increase in heat losses leads to a discontinuity of
the steady state response curve, with flames extinguishing inside a finite
interval of the flow rate. Non symmetric flames burn more intensely and in
consequence are much more robust to flame quenching by heat losses to the
walls. The inclusion of the non symmetric solutions extends therefore the
parametric range for which flames can propagate in the channel. This analysis
seems to have received no attention in the literature, even if it can have
important safety implications in micro scale combustion devices burning
hydrogen in a lean premixed way.

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The categories of this paper are: plasm-ph
29
The categories of this paper are: funct-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
1
The categories of this paper are: cs
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The categories of this paper are: eess
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: supr-con