The Linear-Eddy Model

Menon, Suresh; Kerstein, Alan R.

doi:10.1007/978-94-007-0412-1_10

Cited by 67 publications

(46 citation statements)

References 77 publications

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“…Details of this procedure, which are presented in the cited references, are not repeated here because the present approach is only indirectly related to splicing. A survey of LES/LEM applications to date is given by Menon and Kerstein [14]. Similar, if not greater, impact can be anticipated by coupling LEM3D to RANS or LES and eventually to ODTLES [15,16].…”

Section: Strategies For Lem Coupling To 3d Flow Solutionsmentioning

confidence: 87%

Stochastic Simulation of Scalar Mixing Capturing Unsteadiness and Small-scale Structure Based on Mean-flow Properties

Sannan

Weydahl

Kerstein

2012

Flow Turbulence Combust

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A key limitation of Reynolds-Average Navier-Stokes (RANS) simulation of mixing and reaction in turbulent flows is the lack of resolution of small-scale structure and associated unsteadiness. Various subgrid models formulated in state space have been developed to complement the RANS solution in this regard. We here introduce a physical-space formulation that captures unsteady advective and diffusive processes at all scales of the turbulent flow. The approach is a 3D construction based on the Linear Eddy Model (LEM), involving three orthogonally intersecting arrays of 1D LEM domains, and coupled so as to capture the 3D character of fluid trajectories. To illustrate the model performance of the 3D LEM-based formulation, here termed LEM3D, multi-stream mixing in a turbulent round jet is simulated using measured mean-flow properties as input. Comparison to scalar crosscorrelation coefficients and other measured properties of this mixing configuration indicate that the LEM3D approach, in conjunction with flow properties that are provided by steady-state models, is a useful representation of complex turbulent mixing processes that would otherwise be difficult to capture within a steady-state CFD framework.

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Section: Strategies For Lem Coupling To 3d Flow Solutionsmentioning

confidence: 87%

Stochastic Simulation of Scalar Mixing Capturing Unsteadiness and Small-scale Structure Based on Mean-flow Properties

Sannan

Weydahl

Kerstein

2012

Flow Turbulence Combust

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“…The details of the 1D LEM as a standalone model (Menon and Kerstein, 2011;Menon et al, 1993) have been reported in details elsewhere and therefore are not repeated here. It has also been implemented as a subgrid model for LES (called LEMLES) (Menon and Kerstein, 2011).…”

Section: Lem Subgrid Modelmentioning

confidence: 99%

“…Sometimes, finite-rate kinetics have to be simulated (e.g., to investigate extinction-ignition physics, lean blow out, and other extreme transient events) and then SGS closure for the reaction rate is explicitly needed. Many closures that address reaction kinetics have been developed, for example (citations are representative and not included to be comprehensive): partially stirred reactor (PaSR) (Fureby, 2009), thickened flame model (TFM) (Colin et al, 2000), flame surface density (FSD) (Boger etal., 1998), conditional moment closure (CMC) (Klimenko and and Bilger, 1999), conditional source estimation (CSE) (Steiner and Bushe, 2001), transported probability density function (TPDF) (Colucci et al, 1998;Gao and O'Brien, 1993), multienvironment PDF (MEPDF) (Fox and Raman, 2004), one-dimensional turbulence (ODT) (Echekki et al, 2001), and linear-eddy mixing (LEM) model (Menon and Kerstein, 2011;Menon et al, 1993), etc. The present article focuses primarily on the LES strategy that allows direct inclusion of finite-rate kinetics and in particular on the LEM based subgrid models.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The two multi-scale implementations of LES as a SGS model include the well established LEM at the subgrid in LES (LEMLES) (Menon and Kerstein, 2011) and a novel reaction-rate closure in LES (RRLES). The strengths and limitations of LEMLES are well known (Menon and Kerstein, 2011) and RRLES is devised to address some of those limitations. For example, the large-scale molecular diffusion across the LES cell faces is ignored in the LEMLES formulation, which leads to inaccurate results when the turbulence is resolved at the LES level as in a DNS or if the turbulence is negligible (laminar conditions).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Subgrid-Scale Modeling of Reaction-Diffusion and Scalar Transport in Turbulent Premixed Flames

Ranjan

Muralidharan

Nagaoka

et al. 2016

Combustion Science and Technology

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A numerical study of premixed flame-turbulence interaction is performed to investigate the effects of turbulence on the structural features of the flame and the subgrid-scale (SGS) effects on vorticity dynamics, energy transfer mechanism, and turbulent transport across the flame. We consider a freely propagating methane-air turbulent premixed flame interacting with a decaying isotropic turbulence under three different initial conditions corresponding to the corrugated flamelet (CF), the thin reaction zone (TRZ), and the broken/ distributed reaction zone (B/DRZ) regimes. We employ the wellestablished linear eddy mixing (LEM) model in large-eddy simulation (LEMLES), a new subgrid closure for reaction-diffusion occurring in the small-scales based on LEM (RRLES), and a quasi-laminar chemistry based closure in large-eddy simulation (QLLES) to simulate flameturbulence interactions and to compare predictions with direct numerical simulation (DNS). We assess the accuracy and robustness of the closures by comparing statistical features to highlight their abilities and limitations. The newly proposed RRLES subgrid closure uses a dual-resolution grid for solving the species transport equations. Such an approach is shown to improve the existing LEMLES subgrid model especially at low Reynolds numbers. All SGS closures reveals good agreement, although there are some differences due to the closure used for convective transport of the scalar field and the reaction rate. Further analysis of the DNS dataset shows that there is a significant contribution by dilatation and baroclinic torque terms across the flame. In particular, at higher Karlovitz number, there is an abrupt change in the sign of the dilatation term, which is related to the competing effects of thermal expansion due to heat release and enhanced molecular mixing by the turbulence across the flame brush region. The enhanced mixing leads to localized pockets of cold reactants surrounded by hot products, which is only partly captured by the employed closures. The analysis of SGS kinetic energy and scalar dissipation rates indicates the presence of back-scatter of turbulent kinetic energy, and we also observe counter-gradient transport across the flame. The results suggest that further improvement of the traditional closures is needed to accurately capture the dynamics of flame-turbulence interaction.ARTICLE HISTORY

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IMEX based multi‐scale time advancement in ODTLES

2018

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In this paper we overcome a key problem in an otherwise highly potential approach to study turbulent flows, ODTLES (One‐Dimensional Turbulence Large Eddy Simulation). From a methodological point of view, ODTLES is an approach in between Direct Numerical Simulations (DNS) and averaged/filtered approaches like RANS (Reynolds Averaged Navier‐Stokes) or LES (Large Eddy Simulations). In ODTLES, a set of 1D ODT models is embedded in a coarse grained 3D LES. On the ODT scale, the turbulent advection is modeled as a sequence of stochastic eddy events, also known as triplet maps, while the other (deterministic) terms are fully resolved in space (along the ODT‐line) and time. Schmidt et al. first (2008) introduced ODTLES and Gonzalez et al. (2011) applied the model for a variety of wall‐bounded flow problems. Although the results were notable for a first proof of concept, the numerical methods used are subject to debate. First of all, an unstable discretization for the large scale 3D advective terms was used, as shown by Glawe (2015). This scheme can be stabilized by reducing the CFL number for the explicitly discretized LES terms down to the order of the small scale ODT time step, but this of course reduces the advantage of the ODTLES multi‐scale approach. The stochastic ODT eddies were also allowed to overlap two LES cells introducing an artificial smoothing (stabilizing) effect. Glawe (2015) limited the overlap consistently to one LES cell and used a stable Runge Kutta (RK) discretization, maintaining, however the low CFL number problem. In this paper we adapt a new implicit/explicit (IMEX) time scheme to ODTLES in order to remedy the small CFL number issue. For the problems investigated, the results indicate a performance increase of the IMEX scheme by a factor of 17 based on the ratio of applied CFL numbers. This allowed simulations of a turbulent channel flow with characteristic friction Reynolds number Reτ=2040 on one Banana Pi single board computer. We compare results to available DNS data and discuss in general the efficiency and potential of ODTLES for high Reynolds number flows.

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The Linear-Eddy Model

Cited by 67 publications

References 77 publications

Stochastic Simulation of Scalar Mixing Capturing Unsteadiness and Small-scale Structure Based on Mean-flow Properties

Stochastic Simulation of Scalar Mixing Capturing Unsteadiness and Small-scale Structure Based on Mean-flow Properties

Subgrid-Scale Modeling of Reaction-Diffusion and Scalar Transport in Turbulent Premixed Flames

IMEX based multi‐scale time advancement in ODTLES

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