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This is a copy of the author 's final draft version of an article published in the journal Flow turbulence and combustion. The final publication is available at Springer via http://dx.doi.org/10.1007/s10494-017-9813-2 ; In the context of Large Eddy Simulation (LES) solely for the momentum transport equation there may be found several models for the turbulent subgrid fluxes. Furthermore, among those relying on the eddy diffusivity approach, each model may be based on different invariants of the strain rate. Besides, when heat and mass transfer are also considered, closures for the subgrid turbulent scalar fluxes are also required. Hence, different model combinations may be considered. Additionally, when other physical phenomena are included, such as combustion, further subgrid modelling is involved. Therefore, in the present study a LES simulation of a turbulent diffusion flame is performed and different combination of subgrid models are used in order to analyse the numerical effects in the simulations. Several models for the turbulent momentum subgrid fluxes are considered, both constant and dynamically evaluated Schmidt numbers. Regarding combustion, in the context of the Flamelet/Progress-Variable (FPV) model, with an assumed probability density function for the turbulent-chemistry interactions and four different closures for the subgrid mixture fraction variance are considered. Hence, a large number of model combinations are possible. The present study highlights the need for a consistent closure of subgrid effects. It is shown that, in the context of an FPV modelling, incorrect capture of subgrid mixing results in a flame lift-off for the studied flame (DLR A diffusion flame), even though experimentally an attached flame was reported. It is found that a consistent formulation is required, that is, all subgrid closures should become active in the same regions of the domain to avoid modelling inconsistencies. In contrast, when the classical flamelet approach is used, no lift-off is observed. The reason is that the classical flamelet includes only a limited subset of the possible flame states, i.e. only includes burning flamelets and extinguished flamelets for scalar dissipation rates past the extinction one. ; The present work has been financially supported by the Ministerio de Economía y Competitividad of the Spanish government through project ENE2014-60577-R. We would also like to thank the reviewers for their helpful comments which have led to an improved article. The authors declare that they have no conflict of interest. ; Peer Reviewed ; Postprint (author's final draft)

This is a copy of the author 's final draft version of an article published in the journal Flow turbulence and combustion. The final publication is available at Springer via http://dx.doi.org/10.1007/s10494-017-9813-2 ; In the context of Large Eddy Simulation (LES) solely for the momentum transport equation there may be found several models for the turbulent subgrid fluxes. Furthermore, among those relying on the eddy diffusivity approach, each model may be based on different invariants of the strain rate. Besides, when heat and mass transfer are also considered, closures for the subgrid turbulent scalar fluxes are also required. Hence, different model combinations may be considered. Additionally, when other physical phenomena are included, such as combustion, further subgrid modelling is involved. Therefore, in the present study a LES simulation of a turbulent diffusion flame is performed and different combination of subgrid models are used in order to analyse the numerical effects in the simulations. Several models for the turbulent momentum subgrid fluxes are considered, both constant and dynamically evaluated Schmidt numbers. Regarding combustion, in the context of the Flamelet/Progress-Variable (FPV) model, with an assumed probability density function for the turbulent-chemistry interactions and four different closures for the subgrid mixture fraction variance are considered. Hence, a large number of model combinations are possible. The present study highlights the need for a consistent closure of subgrid effects. It is shown that, in the context of an FPV modelling, incorrect capture of subgrid mixing results in a flame lift-off for the studied flame (DLR A diffusion flame), even though experimentally an attached flame was reported. It is found that a consistent formulation is required, that is, all subgrid closures should become active in the same regions of the domain to avoid modelling inconsistencies. In contrast, when the classical flamelet approach is used, no lift-off is observed. The reason is that the classical flamelet includes only a limited subset of the possible flame states, i.e. only includes burning flamelets and extinguished flamelets for scalar dissipation rates past the extinction one. ; The present work has been financially supported by the Ministerio de Economía y Competitividad of the Spanish government through project ENE2014-60577-R. We would also like to thank the reviewers for their helpful comments which have led to an improved article. The authors declare that they have no conflict of interest. ; Peer Reviewed ; Postprint (author's final draft)

The use of flux limiters is widespread within the scientific computing community to capture shock dis- continuities and are of paramount importance for the temporal integration of high-speed aerodynamics, multiphase flows and hyperbolic equations in general. Meanwhile, the breakthrough of new computing architectures and the hybridization of supercomputer systems pose a huge portability challenge, particularly for legacy codes, since the computing subroutines that form the algorithms, the so-called kernels, must be adapted to various complex parallel program- ming paradigms. From this perspective, the development of innovative implementations relying on a minimalist set of kernels simplifies the deployment of scientific computing software on state-of-the-art supercomputers, while it requires the reformulation of algorithms, such as the aforementioned flux lim- iters. Equipped with basic algebraic topology and graph theory underlying the classical mesh concept, a new flux limiter formulation is presented based on the adoption of algebraic data structures and kernels. As a result, traditional flux limiters are cast into a stream of only two types of computing kernels: sparse matrix-vector multiplication and generalized pointwise binary operators. The newly proposed formulation eases the deployment of such a numerical technique in massively parallel, potentially hybrid, computing systems and is demonstrated for a canonical advection problem. ; The work of N. V. and X. Á. F. has been supported by the Government of Catalonia, FI AGAUR predoctoral grants 2019FI_B2_ 000104 and 2019FI_B2_00076. N. V., X. Á. F., J. C., A. O. and F. X. T. have been funded by the Spanish Research Agency, ANUMESOL project ENE2017-88697-R. J. C. has also been funded by Spanish Research Agency, GALIFLOW project ENE2015-70662-P. The studies of this work have been carried out using the MareNostrum 4 supercomputer of the Barcelona Supercomput- ing Center, projects IM-2019-3-0026 and IM-2020-1-0006; the TSUBAME3.0 supercomputer of the Global Scientific Information and Computing Center at Tokyo Institute of Technology; the Lomonosov-2 supercomputer of the shared research facilities of HPC computing resources at Lomonosov Moscow State University; the K-60 hybrid cluster of the collective use center of the Keldysh Institute of Applied Mathematics; the JFF cluster of the Heat and Mass Transfer Technological Center at Technical University of Cat- alonia. The authors thankfully acknowledge these institutions for the compute time and technical support. ; Peer Reviewed ; Postprint (published version)