A Similarity Subgrid Model for Premixed Turbulent Combustion |
| |
Authors: | A W Vreman R J M Bastiaans B J Geurts |
| |
Institution: | (1) Combustion Technology, Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands;(2) Vreman Research, Godfried Bomansstraat 46, 7552 NT Hengelo, The Netherlands;(3) Mathematical Sciences, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands;(4) Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands |
| |
Abstract: | The accuracy of large-eddy simulation (LES) of a turbulent premixed Bunsen flame is investigated in this paper. To distinguish
between discretization and modeling errors, multiple LES, using different grid sizes h but the same filterwidth Δ, are compared with the direct numerical simulation (DNS). In addition, LES using various values
of Δ but the same ratio Δ/h are compared. The chemistry in the LES and DNS is parametrized with the standard steady premixed flamelet for stochiometric
methane-air combustion. The subgrid terms are closed with an eddy-viscosity or eddy-diffusivity approach, with an exception
of the dominant subgrid term, which is the subgrid part of the chemical source term. The latter subgrid contribution is modeled
by a similarity model based upon 2Δ, which is found to be superior to such a model based upon Δ. Using the 2Δ similarity model
for the subgrid chemistry the LES produces good results, certainly in view of the fact that the LES is completely wrong if
the subgrid chemistry model is omitted. The grid refinements of the LES show that the results for Δ = h do depend on the numerical scheme, much more than for h = Δ/2 and h = Δ/4. Nevertheless, modeling errors and discretization error may partially cancel each other; occasionally the Δ = h results were more accurate than the h ≤ Δ results. Finally, for this flame LES results obtained with the present similarity model are shown to be slightly better
than those obtained with standard β-pdf closure for the subgrid chemistry. |
| |
Keywords: | Large-eddy simulation Similarity models Turbulent combustion Premixed flamelets |
本文献已被 SpringerLink 等数据库收录! |
|