The importance of the turbulent combustion model

The turbulent combustion model is a key element in the CFD modelling process. It provides the coupling between the turbulent flow and the chemical reactions, both for RANS and LES methods. The key difficulties with including chemical reactions in CFD simulations are as follows:

• The chemical reactions occur at time and length scales which are several orders of magnitude smaller than the characteristic scales of the turbulent flow (the so-called sub-grid level).
• The chemical reactions depend non-linearly on temperature and composition, which can strongly fluctuate in turbulent flows.

The assumptions underlying the interaction of the chemical reactions with the turbulent flow form the basis of a turbulent combustion model, as illustrated by the image on the right, representing a simulation of a mixture fraction field originating from a Diesel jet.

Integration of combustion models in CFD software

The implementation of turbulent combustion models in CFD software is a specialised task. Although most CFD software providers have integrated one or several turbulent combustion models in their CFD code, many industrial CFD users have invested in their own turbulent combustion model developments, often in partnership with academic institutions. In order to fully benefit from this investment, it is critical that the developments are rapidly implemented in the industrial CFD process.

Dacolt is well-placed to perform this type of model implementation, with its in-depth and up-to-date knowledge of the various modelling approaches available. Dacolt has realised several custom model implementations over the last years, for various types of models, both in proprietary and Open Source CFD software packages.

Contact us for more information on combustion model integration.