Positivity Issues in Adaptive Solutions of Detailed Chemical Schemes for Engine Simulations

Laura Antonelli, Maya Briani, Pasqua D’Ambra, Valentina Fraioli


Reliable and efficient solution of chemical kinetics is one
of the main computational kernels in engine simulations.
The chemical schemes are characterized by high degrees of stiffness, due
to the very different reaction rates, and include intermediate
species with low density, whose accurate solution is
needed to well understand the combustion process. In this
context non-negativity property of the numerical methods for the ordinary
differential equations is crucial for avoiding spurious numerical instabilities
and very high accuracy requests. In this work we discuss results
obtained by using a recent version of the VODE package which allows to impose
non-negativity constraints on the solution, in simulations of combustion when a moderate
size chemical scheme is used. The impact of positivity requirements on the total mass preservation
and the computational cost is analyzed for a classic model problem for which experimental data
are available for validation.

[DOI: 10.1685/CSC09303] About DOI


detailed reaction schemes, stiff ODE solvers, positivity preservation, combustion modeling

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DOI: http://dx.doi.org/10.1685/

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