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    Wyświetlanie 1-3 z 3
    Tytuł:
    Efficient implementation of a compact-pseudospectral method for turbulence modeling
    Autorzy:
    Tyliszczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955215.pdf
    Data publikacji:
    2006
    Wydawca:
    Politechnika Gdańska
    Tematy:
    large eddy simulation
    compact scheme
    channel flow
    Opis:
    The paper is devoted to parallel implementation of a compact discretization scheme com-bined with the Fourier pseudospectral method. The idle time of processors resulting from the method of computating derivatives using compact schemes is eliminated by proper ordering of subtasks and by performing useful computations when processors are waiting for data from their neighbors. The correctnes of the algorithm is confirmed by comparison of results of LES simulations with DNS data for flow in a 3D channel with periodic non-slip wall boundary conditions.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 125-138
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    LES-CMC and LES-Flamelet simulation of non-premixed methane flame (Sandia F)
    Autorzy:
    Tyliszczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/280055.pdf
    Data publikacji:
    2013
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    localised extinction
    piloted flame
    large eddy simulation
    conditional moment closure
    flamelet
    Opis:
    In this paper, the Large Eddy Simulation (LES) together with the Conditional Moment Closure (CMC) and flamelet combustion models have been applied for modelling of methane flame Sandia F. In the case of the CMC model, both instantaneous and time averaged values predicted numerically agree well with measurements. Attention was devoted to modelling aspects of the conditional scalar dissipation rate (SDR), which is a key quantity of the CMC approach. The two methods of computing SDR are compared with emphasis on a correct prediction of localised extinctions and on their influence on the mean values. It was found that the method of modelling of SDR has rather minor impact on the instantaneous values, whereas larger differences were observed in statistics. In the case of the flamelet model, although it is not able to predict extinctions and re-ignition, the mean values were in good agreement with the experiment.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2013, 51, 4; 859-871
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Attenuating and enhancing properties of the approximate deconvolution method based on higher-order explicit and compact filters
    Autorzy:
    Caban, L.
    Tyliszczak, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/38695731.pdf
    Data publikacji:
    2023
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    explicit filter
    compact filter
    van Cittert deconvolution method
    signal analysis
    sub-filter scales reconstruction
    Large Eddy Simulation
    Opis:
    We analyse the accuracy of a deconvolution (inverse filtering) method in 1D and 2D periodic domains. The deconvolution is performed by applying the iterative van Cittert method using explicit and compact filters of the 2nd to 8th order. We consider cases in which an approximate inverse filter $ G_\alpha^{-1} $ formulated to deconvolve an original function from a filtered one $ ( \overline{f} = G \ast f ) $ is constructed based on: (a) $G$ the same as used to define $ \overline{f} = G \ast f $; (b) $ G $ different than the one used to define $ \overline{f} = G \ast f $. In case (a), the convergence rate of the deconvolution process is much better when compact filters are used. This is attributed to a flatter transfer function of this type of filter and thus a smaller deterioration of the input function $ \overline{f} $. Case (b) reflects a real situation in which the precise definition of a basic filter $G$ used in $ \overline{f} = G \ast f $ is unknown. We found that when $ G_\alpha^{-1} $ is formulated based on $G$ of a higher order than the one used to define $ \overline{f} $ the reconstructed function $ f^\ast = G_\alpha^{-1} \ast \overline{f} $ is suppressed compared to the original function $f$. On the other hand, the deconvolution process performed with the use of $ G_\alpha^{-1} $ defined based on $G$ of a lower order than the order of the basic filter significantly amplifies the reconstructed function $ f^\ast $. As a result, the function $ f^\ast $ contains more energy than the function $f$, especially in the range of small and high-frequency scales. This effect is particularly strong when explicit filters of different orders are used. The impact of the filter type in the practical application of deconvolution is demonstrated based on large eddy simulations (LES) of a 2D decaying homogenous turbulent flow. LES combined with an approximate deconvolution method (ADM) for the computation of sub-filter terms shows better accuracy than in the case when these terms are modelled using the classical Smagorinsky model or when they are neglected (no-model approach). This analysis consists of comparisons of the evolution of total energy, energy spectra, and higher-order moments (variance, skewness, kurtosis) of the velocity components and vorticity. We found that more accurate results are obtained when the deconvolution is performed using the explicit filters even if the deconvolution process based on the compact filters was found to converge faster in 1D and 2D test cases. Most likely this is because in the performed LES the explicit filters correspond better to an unknown filter induced by discretisation.
    Źródło:
    Archives of Mechanics; 2023, 75, 1-2; 107-149
    0373-2029
    Pojawia się w:
    Archives of Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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