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A thickened stochastic fields approach for turbulent combustion simulation

A thickened stochastic fields approach for turbulent combustion simulation
A thickened stochastic fields approach for turbulent combustion simulation
The Stochastic Fields approach is an effective way to implement transported Probability Density Function modelling into Large Eddy Simulation of turbulent combustion. In premixed turbulent combustion however, thin flame-like structures arise in the solution of the Stochastic Fields equations that require grid spacing much finer than the filter scale used for the Large Eddys Simulation. The conventional approach of using grid spacing equal to the filter scale yields substantial numerical error, whereas using grid spacing much finer than the filter length scale is computationally-unaffordable for most industrially-relevant combustion systems. A Partially-Thickened Stochastic Fields approach is developed in this study in order to provide physically accurate and numerically-converged solutions of the Stochastic Fields equations with reduced compute time. The Partially-Thickened Stochastic Fields formulation bridges between the conventional Stochastic Fields and conventional Thickened-Flame approaches depending on the numerical grid spacing utilised, and converges towards Direct Numerical Simulation in the limit of full-resolution. One-dimensional Stochastic Fields simulations of freely-propagating turbulent premixed flames are used in order to obtain criteria for the thickening factor required, as a function of relevant physical and numerical parameters, and to obtain a model for an efficiency function that accounts for the loss of resolved flame surface area caused by applying the thickening transformation to the Stochastic Fields equations. The Thickened Stochastic Fields formulation is tested by performing LES of a laboratory Bunsen flame, demonstrating that the method leads to numerically-converged simulations that agree with results of conventional Stochastic Fields simulations using orders of magnitude more grid points. The present development therefore facilitates the accurate application of the Stochastic Fields approach to industrially-relevant combustion systems.
Stochastic Fields, Large Eddy Simulation (LES), Thickened Flame, Combustion, Turbulence
Picciani, Mark, Anthony
f4318820-e11c-4345-af24-23806ce825b9
Richardson, Edward
a8357516-e871-40d8-8a53-de7847aa2d08
Navarro-Martinez, Salvador
d48d5fb3-09f0-4cbd-8473-0d70b787fd31
Picciani, Mark, Anthony
f4318820-e11c-4345-af24-23806ce825b9
Richardson, Edward
a8357516-e871-40d8-8a53-de7847aa2d08
Navarro-Martinez, Salvador
d48d5fb3-09f0-4cbd-8473-0d70b787fd31

Picciani, Mark, Anthony, Richardson, Edward and Navarro-Martinez, Salvador (2018) A thickened stochastic fields approach for turbulent combustion simulation. Tenth Mediterranean Combustion Symposium, , Napoli, Italy. 17 - 21 Sep 2017. 12 pp .

Record type: Conference or Workshop Item (Paper)

Abstract

The Stochastic Fields approach is an effective way to implement transported Probability Density Function modelling into Large Eddy Simulation of turbulent combustion. In premixed turbulent combustion however, thin flame-like structures arise in the solution of the Stochastic Fields equations that require grid spacing much finer than the filter scale used for the Large Eddys Simulation. The conventional approach of using grid spacing equal to the filter scale yields substantial numerical error, whereas using grid spacing much finer than the filter length scale is computationally-unaffordable for most industrially-relevant combustion systems. A Partially-Thickened Stochastic Fields approach is developed in this study in order to provide physically accurate and numerically-converged solutions of the Stochastic Fields equations with reduced compute time. The Partially-Thickened Stochastic Fields formulation bridges between the conventional Stochastic Fields and conventional Thickened-Flame approaches depending on the numerical grid spacing utilised, and converges towards Direct Numerical Simulation in the limit of full-resolution. One-dimensional Stochastic Fields simulations of freely-propagating turbulent premixed flames are used in order to obtain criteria for the thickening factor required, as a function of relevant physical and numerical parameters, and to obtain a model for an efficiency function that accounts for the loss of resolved flame surface area caused by applying the thickening transformation to the Stochastic Fields equations. The Thickened Stochastic Fields formulation is tested by performing LES of a laboratory Bunsen flame, demonstrating that the method leads to numerically-converged simulations that agree with results of conventional Stochastic Fields simulations using orders of magnitude more grid points. The present development therefore facilitates the accurate application of the Stochastic Fields approach to industrially-relevant combustion systems.

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Picciani_ThickenedStochasticFields_MCS_2017 - Accepted Manuscript
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More information

Accepted/In Press date: 18 May 2017
Published date: 17 August 2018
Venue - Dates: Tenth Mediterranean Combustion Symposium, , Napoli, Italy, 2017-09-17 - 2017-09-21
Keywords: Stochastic Fields, Large Eddy Simulation (LES), Thickened Flame, Combustion, Turbulence
Organisations: Aerodynamics & Flight Mechanics Group, Education Hub

Identifiers

Local EPrints ID: 410559
URI: http://eprints.soton.ac.uk/id/eprint/410559
PURE UUID: 3d00ee0d-9e15-4e23-ba0e-d333fa2ae523

Catalogue record

Date deposited: 09 Jun 2017 09:05
Last modified: 21 Nov 2021 06:48

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Contributors

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

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