New paper on advanced modeling of multicomponent diffusion

paper droplet evaporation

🎉 I am glad to announce the publication of our latest work, developed in close collaboration between the CRECK Modeling Lab (Politecnico di Milano) and our colleagues at CIEMAT and UNED (Madrid, Spain): â€śComplete multicomponent versus mixture-averaged calculations of a laminar H/N diffusion flame including heat transfer at the burner and Soret effects”.

This study presents the implementation and application of the 1+M multicomponent diffusion formulation in the laminarSMOKE++ CFD solver. This optimized framework allows for the treatment of Fick and Soret diffusion terms derived from the Kinetic Theory of Gases (KTG), at a computational cost comparable to traditional mixture-averaged formulations.

In this work, we explore the behavior of an axisymmetric H2/N2 laminar coflow diffusion flame, comparing different diffusion models (unity Lewis, mixture-averaged, full multicomponent) under both adiabatic and non-adiabatic wall conditions. A key finding: when Soret effects and heat transfer are considered together, simplified diffusion models can yield significantly inaccurate predictions, especially near the burner rim and on the lean side of the flame.

We are particularly proud that OpenSMOKE++ was used as the chemical kinetics engine in all simulations—providing high-fidelity evaluations of thermodynamic, transport, and reaction properties required to resolve the detailed chemistry involved in these diffusion flames.

Thanks to this integration, laminarSMOKE++ now offers an affordable and accurate multicomponent transport framework, which is especially critical for laminar reacting flows with wall heat losses, low reactivity flames, and hydrogen-containing fuels.

🔥 Explore the full paper and model here: https://www.sciencedirect.com/science/article/pii/S0360319924057124?via%3Dihub

Naud, B., Arias-Zugasti, M. and Cuoci, A., 2025. Complete multicomponent versus mixture-averaged calculations of a laminar H2/N2 diffusion flame including heat transfer at the burner and Soret effects. International Journal of Hydrogen Energy, DOI: https://doi.org/10.1016/j.ijhydene.2024.12.493

 

Abstract

The implementation of full multicomponent treatment of diffusion fluxes in the CFD solver for laminar reacting flows with detailed kinetic mechanisms laminarSMOKE++ is presented. The optimised 1+M multicomponent formulation (including Fick diffusion and Soret effects) derived from the Kinetic Theory of Gases, with a similar computational cost as mixture-averaged, is considered. Results are presented for a H2/N2 laminar coflow diffusion flame, where either heat transfer at the burner wall is included, either the wall is considered adiabatic. We observe that full multicomponent and mixture-averaged results are very similar when Soret effects are neglected. However, differences are observed when including thermodiffusion. In particular with heat transfer at the wall, large differences are observed whether thermodiffusion is neglected or included. In this case, the mixture-averaged approximation used for the thermal diffusion coefficients leads to significant differences in the results compared to the full multicomponent 1+formulation.

 

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