Experimental assessment of presumed filtered density function models
File(s)
Accepted version
Published version
Author(s)
Stetsyuk, V
Soulopoulos, N
Hardalupas, I
Taylor, AMKP
Type
Journal Article
Abstract
Measured filtered density functions (FDFs) as well as assumed beta distribution model of mixture fraction and “subgrid” scale (SGS) scalar variance z′′2⎯⎯⎯⎯⎯⎯⎯, used typically in large eddy simulations, were studied by analysing experimental data, obtained from two-dimensional planar, laser induced fluorescence measurements in isothermal swirling turbulent flows at a constant Reynolds number of 29 000 for different swirl numbers (0.3, 0.58, and 1.07). Two-dimensional spatial filtering, by using a box filter, was performed in order to obtain the filtered variables, namely, resolved mean and “subgrid” scale scalar variance. These were used as inputs for assumed beta distribution of mixture fraction and top-hat FDF shape estimates. The presumed beta distribution model, top-hat FDF, and the measured filtered density functions were used to integrate a laminar flamelet solution in order to calculate the corresponding resolved temperature. The experimentally measured FDFs varied with the flow swirl number and both axial and radial positions in the flow. The FDFs were unimodal at flow regions with low SGS scalar variance, z′′2⎯⎯⎯⎯⎯⎯⎯< 0.01, and bimodal at regions with high SGS variance, z′′2⎯⎯⎯⎯⎯⎯⎯> 0.02. Bimodal FDF could be observed for a filter size of approximately 1.5-2 times the Batchelor scale. Unimodal FDF could be observed for a filter size as large as four times the Batchelor scale under well-mixed conditions. In addition, two common computational models (a gradient assumption and a scale similarity model) for the SGS scalar variance were used with the aim to evaluate their validity through comparison with the experimental data. It was found that the gradient assumption model performed generally better than the scale similarity one.
Date Issued
2015-06-10
Date Acceptance
2015-05-26
Citation
Physics of Fluids, 2015, 27 (6), pp.065107-1-065107-19
ISSN
1070-6631
Publisher
American Institute of Physics
Start Page
065107-1
End Page
065107-19
Journal / Book Title
Physics of Fluids
Volume
27
Issue
6
Copyright Statement
© 2015 Author(s). Published under a Creative Commons CC BY licence.
License URL
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (E
Identifier
https://aip.scitation.org/doi/10.1063/1.4922169
Grant Number
GR/R01750/01
GR//R54767/01
J13878
Subjects
Science & Technology
Technology
Physical Sciences
Mechanics
Physics, Fluids & Plasmas
Physics
LARGE-EDDY SIMULATION
TURBULENT
COMBUSTION
VARIANCE
LES
01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Fluids & Plasmas
Publication Status
Published
Article Number
065107
Date Publish Online
2015-06-10