Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer (MHMT'23)
London, United Kingdom – April, 2024
Paper No. CSP 101
DOI: 10.11159/csp24.101

Sensitivity Analysis of Simulation Parameters on Premixed
Propagating Flames: Impact of XiFOAM Discretization Schemes
1

Ayushi Mishra1, Mayank Kumar1, Krishnakant Agarwal1

Department of Mechanical Engineering, Indian Institute of Technology Delhi
New Delhi-110016, India
ayushi.mishra@mech.iitd.ac.in; mayank.kumar@mech.iitd.ac.in; kkant@mech.iitd.ac.in

Extended Abstract

This paper uses the OpenFOAM Computational Fluid Dynamics (CFD) code to study the turbulent premixed flame
propagation characteristics inside a partially open duct filled with obstacles. The simulation results were validated across theexperimental results by Patel et al.[1], the experiments were carried out in a rectangular duct of small scale with dimensionsof 500×150×150mm, which was open from one end and filled with three equally spaced rectangular obstacles along thecentreline. All the simulations were performed using a two-dimensional model with realizable k-ε turbulence modeling andthe Flame Surface Density (FSD) model proposed by Weller et al.[2] for Combustion modeling. The solver uses an adaptive
time-stepping method coupled with a maximum value of the Courant number.
Initially, the simulations were carried out with a first-order upwind scheme (limited linear with a limiting coefficient ofone [3]) for divergence terms, a second-order Crank Nicolson method for time discretization, and a PIMPLE solver (withouter correctors set to 200 with residual for outer correctors set to 10-4) for pressure-velocity coupling. The solution withthese schemes resulted in impractical dependence of pressure peak on the initial values of simulation parameters: turbulent
kinetic energy ‘k’, initial time step size ‘Δt’, mesh size ‘Δx’ as well as the maximum value for Courant number of the flow
‘maxCo’. The k values tested are 0.5, 0.1, 0.05, and 0.01, as at 0.01 the pressure peak was negligible and far delayed. Similar
results have been obtained for the above-mentioned parameters, whereupon reducing Δx, Δt or maxCo, the flame failed topropagate, resulting in no pressure peak at all. For some cases, the pressure plots have shown oscillatory behavior, andcorrespondingly, the flame structure was also seen to be more wrinkled compared to the experimental results. Thediscretization schemes were updated to a second-order linear scheme (limited linear with a coefficient of zero) for divergenceterms and a first-order Euler method for temporal terms. The pressure velocity coupling was updated to an iterative PISO
algorithm (PIMPLE in OpenFOAM, with outer correctors of three). The updated solver was then tested against theexperimental results to analyze the dependence of pressure peak on the above-mentioned simulation parameters. It was foundthat the unexpected dependence was eliminated, and the solver provided reasonably good qualitative agreement with theexperimental results for k=0.01. The solution became independent of the other parameters as well, and grid independence
was also obtained for the results. The effect of each of the discretization schemes is also tested individually, and it was foundthat the significant effect was found to be of the Crank Nicolson method due to its diffusive nature and difficulty in accurately
resolving the discontinuity across the flamelet.

References
[1]
[2]
[3]

S. N. D. H. Patel, S. Jarvis, S. S. Ibrahim, and G. K. Hargrave, “An experimental and numerical investigation ofpremixed flame deflagration in a semiconfined explosion chamber,” Proc. Combust. Inst., vol. 29, no. 2, pp. 1849–1854, 2002, doi: 10.1016/S1540-7489(02)80224-3.
H. G. Weller, G. Tabor, A. D. Gosman, and C. Fureby, “Application of a flame-wrinkling les combustion model to a
turbulent mixing layer,” Symp. Combust., vol. 27, no. 1, pp. 899–907, 1998, doi: 10.1016/S0082-0784(98)80487-6.
E. Robertson, V. Choudhury, S. Bhushan, and D. K. Walters, “Validation of OpenFOAM numerical methods andturbulence models for incompressible bluff body flows,” Comput. Fluids, vol. 123, pp. 122–145, 2015, doi:
10.1016/j.compfluid.2015.09.010.

CSP 101-1