The University of Southampton
University of Southampton Institutional Repository
Warning ePrints Soton is experiencing an issue with some file downloads not being available. We are working hard to fix this. Please bear with us.

Resolution requirements in stochastic field simulation of turbulent premixed flames

Resolution requirements in stochastic field simulation of turbulent premixed flames
Resolution requirements in stochastic field simulation of turbulent premixed flames
The spatial resolution requirements of the Stochastic Fields probability density function approach are investigated in the context of turbulent premixed combustion simulation. The Stochastic Fields approach is an attractive way to implement transported Probability Density Function modelling into Large Eddy Simulations of turbulent combustion. In premixed combustion LES, the numerical grid should resolve flame-like structures that arise from solution of the Stochastic Fields equation. Through analysis of Stochastic Fields simulations of a freely-propagating planar turbulent premixed flame, it is shown that the flame-like structures in the Stochastic Fields simulations can be orders of magnitude narrower than the LES filter length scale, implying that the usual practice of setting the LES filter length scale equal to grid spacing leads to severe under-resolution, to numerical thickening of the flame, and to substantial error in the turbulent flame speed. The under-resolution is worst for low Karlovitz number combustion, where the thickness of the Stochastic Fields flame structures is similar to the laminar flame thickness. The effect of resolution on LES predictions is then assessed by performing LES of a laboratory Bunsen flame and comparing the effect of refining the grid spacing and filter length scale independently. The Bunsen flame LES results confirm that setting the LES filter length scale equal to the grid spacing gives substantial numerical error, and that this error affects the Stochastic Fields solution to a greater extent than it affects the flow field solution. The present results have important implications for application of the Stochastic Fields approach to simulation of high-pressure industrial premixed combustion systems where the grid spacing is necessarily much larger than the laminar flame thickness and suggests that some amount of artificial flame thickening might be needed in order to make such simulations numerically accurate.
Stochastic Fields, large eddy simulation (les), Turbulence, Combustion, Resolution
Picciani, Mark, Anthony
f4318820-e11c-4345-af24-23806ce825b9
Navarro-Martinez, Salvador
9ea4b95c-0c53-43a4-99e8-4cbfa6a53b7d
Richardson, Edward
a8357516-e871-40d8-8a53-de7847aa2d08
Picciani, Mark, Anthony
f4318820-e11c-4345-af24-23806ce825b9
Navarro-Martinez, Salvador
9ea4b95c-0c53-43a4-99e8-4cbfa6a53b7d
Richardson, Edward
a8357516-e871-40d8-8a53-de7847aa2d08

Picciani, Mark, Anthony, Navarro-Martinez, Salvador and Richardson, Edward (2018) Resolution requirements in stochastic field simulation of turbulent premixed flames. Mediterranean Combustion Symposium, , Naples, Italy. 16 - 22 Sep 2017. 12 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

The spatial resolution requirements of the Stochastic Fields probability density function approach are investigated in the context of turbulent premixed combustion simulation. The Stochastic Fields approach is an attractive way to implement transported Probability Density Function modelling into Large Eddy Simulations of turbulent combustion. In premixed combustion LES, the numerical grid should resolve flame-like structures that arise from solution of the Stochastic Fields equation. Through analysis of Stochastic Fields simulations of a freely-propagating planar turbulent premixed flame, it is shown that the flame-like structures in the Stochastic Fields simulations can be orders of magnitude narrower than the LES filter length scale, implying that the usual practice of setting the LES filter length scale equal to grid spacing leads to severe under-resolution, to numerical thickening of the flame, and to substantial error in the turbulent flame speed. The under-resolution is worst for low Karlovitz number combustion, where the thickness of the Stochastic Fields flame structures is similar to the laminar flame thickness. The effect of resolution on LES predictions is then assessed by performing LES of a laboratory Bunsen flame and comparing the effect of refining the grid spacing and filter length scale independently. The Bunsen flame LES results confirm that setting the LES filter length scale equal to the grid spacing gives substantial numerical error, and that this error affects the Stochastic Fields solution to a greater extent than it affects the flow field solution. The present results have important implications for application of the Stochastic Fields approach to simulation of high-pressure industrial premixed combustion systems where the grid spacing is necessarily much larger than the laminar flame thickness and suggests that some amount of artificial flame thickening might be needed in order to make such simulations numerically accurate.

Text
Picciani_StochasticFieldsResolution_MCS_2017 - Accepted Manuscript
Download (1MB)

More information

Accepted/In Press date: 18 May 2017
Published date: 14 August 2018
Venue - Dates: Mediterranean Combustion Symposium, , Naples, Italy, 2017-09-16 - 2017-09-22
Keywords: Stochastic Fields, large eddy simulation (les), Turbulence, Combustion, Resolution
Organisations: Aerodynamics & Flight Mechanics Group, Education Hub

Identifiers

Local EPrints ID: 410560
URI: http://eprints.soton.ac.uk/id/eprint/410560
PURE UUID: 5a7ead81-3052-4e5f-b3a0-842f252e5519

Catalogue record

Date deposited: 09 Jun 2017 09:06
Last modified: 25 Nov 2021 22:23

Export record

Contributors

Author: Mark, Anthony Picciani
Author: Salvador Navarro-Martinez

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×