Scale-similarity models for the chemical source terms in large eddy simulation
(2025) In Combustion Theory and Modelling 29(4). p.456-486- Abstract
The modelling of filtered chemical source terms remains a fundamental challenges for large eddy simulation (LES) of reacting flows, such as combustion. This study investigates various scale similarity models for predicting filtered reaction rates. The theoretical foundation of scale similarity models is reviewed, and several extensions and generalisations are proposed. These include the distinction of additive and multiplicative models, multi-level models, differential models and a re-interpretation of scale similarity models as regression models. The proposed models are assessed in a comprehensive set of test cases. A priori evaluation is performed on laminar premixed flames, laminar diffusion flames and turbulent premixed flames.... (More)
The modelling of filtered chemical source terms remains a fundamental challenges for large eddy simulation (LES) of reacting flows, such as combustion. This study investigates various scale similarity models for predicting filtered reaction rates. The theoretical foundation of scale similarity models is reviewed, and several extensions and generalisations are proposed. These include the distinction of additive and multiplicative models, multi-level models, differential models and a re-interpretation of scale similarity models as regression models. The proposed models are assessed in a comprehensive set of test cases. A priori evaluation is performed on laminar premixed flames, laminar diffusion flames and turbulent premixed flames. Different fuels and reaction mechanisms are used, including hydrogen, methane, ethene, methanol and n-heptane. The study reveals that multiplicative scale similarity models, particularly those incorporating differential and multi-level strategies, consistently outperform additive models and the perfectly stirred reactor model. Differential models, which reduce the size of test filters, demonstrate marked improvements in accuracy without affecting the computational cost of the model. Reactions with negative activation energies pose a difficulty for the models, leading to higher errors. In a simple a posteriori test the accumulation of model error over time is evaluated. It is found that frequent updates to the scaling factors are essential to maintaining accuracy over time, and this requirement underscores the importance of balancing computational cost with model accuracy in practical LES applications. The findings suggest that scale similarity models, particularly multiplicative and differential variants, have potential to be used in practical LES of reacting flows.
(Less)
- author
- Nilsson, Thommie LU
- organization
- publishing date
- 2025
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- combustion model, Scale similarity, simulation, subgrid model
- in
- Combustion Theory and Modelling
- volume
- 29
- issue
- 4
- pages
- 31 pages
- publisher
- Taylor & Francis
- external identifiers
-
- scopus:105007551728
- ISSN
- 1364-7830
- DOI
- 10.1080/13647830.2025.2515030
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
- id
- 6f52730b-79a5-4477-8823-af7851e3d056
- date added to LUP
- 2025-12-18 10:38:51
- date last changed
- 2025-12-18 10:39:37
@article{6f52730b-79a5-4477-8823-af7851e3d056,
abstract = {{<p>The modelling of filtered chemical source terms remains a fundamental challenges for large eddy simulation (LES) of reacting flows, such as combustion. This study investigates various scale similarity models for predicting filtered reaction rates. The theoretical foundation of scale similarity models is reviewed, and several extensions and generalisations are proposed. These include the distinction of additive and multiplicative models, multi-level models, differential models and a re-interpretation of scale similarity models as regression models. The proposed models are assessed in a comprehensive set of test cases. A priori evaluation is performed on laminar premixed flames, laminar diffusion flames and turbulent premixed flames. Different fuels and reaction mechanisms are used, including hydrogen, methane, ethene, methanol and n-heptane. The study reveals that multiplicative scale similarity models, particularly those incorporating differential and multi-level strategies, consistently outperform additive models and the perfectly stirred reactor model. Differential models, which reduce the size of test filters, demonstrate marked improvements in accuracy without affecting the computational cost of the model. Reactions with negative activation energies pose a difficulty for the models, leading to higher errors. In a simple a posteriori test the accumulation of model error over time is evaluated. It is found that frequent updates to the scaling factors are essential to maintaining accuracy over time, and this requirement underscores the importance of balancing computational cost with model accuracy in practical LES applications. The findings suggest that scale similarity models, particularly multiplicative and differential variants, have potential to be used in practical LES of reacting flows.</p>}},
author = {{Nilsson, Thommie}},
issn = {{1364-7830}},
keywords = {{combustion model; Scale similarity; simulation; subgrid model}},
language = {{eng}},
number = {{4}},
pages = {{456--486}},
publisher = {{Taylor & Francis}},
series = {{Combustion Theory and Modelling}},
title = {{Scale-similarity models for the chemical source terms in large eddy simulation}},
url = {{http://dx.doi.org/10.1080/13647830.2025.2515030}},
doi = {{10.1080/13647830.2025.2515030}},
volume = {{29}},
year = {{2025}},
}