Assessment of Dynamic Closure for Premixed Combustion LES
Combustion Theory and Modelling
Taylor & Francis
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Langella, I., Swaminathan, S., Gao, Y., & Chakraborty, N. (2015). Assessment of Dynamic Closure for Premixed Combustion LES. Combustion Theory and Modelling, 19 628-656. https://doi.org/10.1080/13647830.2015.1080387
Turbulent piloted Bunsen flames of stoichiometric methane-air mixture are computed using LES paradigm involving an algebraic closure for the filtered reaction rate. This closure involves filtered scalar dissipation rate of a reaction progress variable. The model for this dissipation rate involves a parameter, !c, representing the flame front curvature effects induced by turbulence, chemical reactions, molecular dissipation, and their interactions at sub-grid level, suggesting that this parameter may vary with filter width or be a scale-dependent. Thus, it would be ideal to evaluate this parameter dynamically in LES. A procedure for this evaluation is discussed and assessed using DNS data and LES calculations. The probability density function of !c obtained from the DNS and LES calculations are very similar when the turbulent Reynolds number is sufficiently large and the filter width normalised by the laminar flame thermal thickness is larger than unity. Results obtained using a constant (static) value for this parameter are also used for comparative evaluation. Detailed discussion presented in this paper suggests that the dynamic procedure works well and physical insights and reasonings are provided to explain the observed behaviour.
Large Eddy Simulation (LES), direct numerical simulation, Scalar Dissipation Rate (SDR), turbulent premixed flame, scale-similarity, dynamic model
This work was supported by the EPSRC, Siemens and Rolls-Royce.
External DOI: https://doi.org/10.1080/13647830.2015.1080387
This record's URL: https://www.repository.cam.ac.uk/handle/1810/249187
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Licence URL: http://creativecommons.org/licenses/by/4.0/