• Turbulent non-premixed combustion
• tabulated chemistry
• presumed PDF
• openFOAM
• methane
• lifted flame
• foam-EXTEND
• unsteady flamelet-progress variable approach

Computational fluid dynamics are nowadays considered to be a fundamental tool for developing combustion technologies. For this reason, there is interest in creating models for treating interaction between chemistry and turbulence: the scope is to obtain reliable method for determining combustion regimes with affordable computational cost for simulating industrial devices.
The present work is focused on Unsteady Flamelet/Progress Variable (UFPV) approach: this type of approach is included in the category of tabulated chemistry and it’s based on the assumption that a non-premixed flame can be considered as an ensemble of laminar non-premixed flamelets.
The implementation of the UFPV approach, with hypothesis of presumed PDFs, has been done on a CFD code (FOAM-extend) for the RANS modelling of a methane lifted flame measured by Cabra et al. within the Vitiated Co-flow burner (VCB) at UC Berkeley.
This implementation has followed the work done by Naud et al. and Winklinger which already modeled an hydrogen lifted flame.
UFPV has given the possibility of including a detailed kinetic mechanism for methane, such as GRI-Mech 3.0: in terms of number of reactions and intermediate species this combustion mechanism is more similar to that one of complex hydrocarbons (n-heptane) rather than hydrogen.