Framework of Coherent Structure Method (CSM) for LES Simulation of Isothermal and Reacting Swirling Flows

Abstract

In this work the Coherent Structure Method (CSM) is used for the simulation of the sub-grid scale (SGS) stress tensor for large eddy simulation of isothermal and reacting turbulent flows. The CSM framework modifies the Smagorinsky coefficient C_s as a function of local flow conditions. It reduces its value where a large coherence of the velocity flow field is detected. In this way the modelled dissipation is reduced and RMS values of velocity, temperature and main species' fluctuations is better reproduced when compared to standard Smagorinsky framework, where C_s is kept constant on a predefined value.
Validation is performed by comparing simulation results with available experimental results of an unconfined swirling premixed natural gas/air flame performed by Schneider et al. in 2005. The simulated flame is the 30 kW lean-premixed PSF-30 flame and according to the authors, this flame contains important characteristics of the industrial flames.