Conditional dissipation of scalars in homogeneous turbulence: closure for MMC modelling

Wandel, Andrew P. (2013) Conditional dissipation of scalars in homogeneous turbulence: closure for MMC modelling. Combustion Theory and Modelling , 17 (4). pp. 707-748. ISSN 1364-7830

Abstract

While the mean and unconditional variance are to be predicted well by any reasonable turbulent combustion model, these are generally not sufficient for the accurate modelling of complex phenomena such as extinction/reignition. An additional criterion has been recently introduced: accurate modelling of the dissipation timescales associated with fluctuations of scalars about their conditional mean (conditional dissipation timescales). Analysis of Direct Numerical Simulation (DNS) results for a passive scalar shows that the conditional dissipation timescale is of the order of the integral timescale and smaller than the unconditional dissipation timescale. A model is proposed: the conditional dissipation timescale is proportional to the integral timescale. This model is used in Multiple Mapping Conditioning (MMC) modelling for a passive scalar case and a reactive scalar case, comparing to DNS results for both. The results show that this model improves the accuracy of MMC predictions so as to match the DNS results more closely using a relatively-coarse spatial resolution compared to other turbulent combustion models.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version due to publisher copyright policy.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Mechanical and Electrical Engineering
Date Deposited: 18 Jul 2013 23:47
Last Modified: 15 Jan 2015 04:33
Uncontrolled Keywords: conditional timescale; direct numerical simulations; multiple mapping conditioning; scalar dissipation; turbulent combustion
Fields of Research : 09 Engineering > 0904 Chemical Engineering > 090405 Non-automotive Combustion and Fuel Engineering (incl. Alternative/Renewable Fuels)
09 Engineering > 0915 Interdisciplinary Engineering > 091508 Turbulent Flows
09 Engineering > 0904 Chemical Engineering > 090407 Process Control and Simulation
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Identification Number or DOI: 10.1080/13647830.2013.794391
URI: http://eprints.usq.edu.au/id/eprint/23769

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