Implicit subgrid-scale modeling by adaptive deconvolution

Adams, Nikolaus A.; Hickel, Stefan; Franz, Sebastian

doi:10.1016/j.jcp.2004.04.010

Cited by 87 publications

(56 citation statements)

References 33 publications

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“…Since with LES the smallest scales are not resolved on the computational grid, effects of these unresolved SGSs must be modelled. We employ an implicit LES approach based on the Adaptive Local Deconvolution (ALDM) method by Adams et al 58 and Hickel et al 59,60 In contrast to explicit SGS models, which are often used for LES of cavitating flows, implicit LES merges turbulence modelling and numerical discretization of the conservation equations. ALDM is a nonlinear finite volume method and incorporates free parameters that control the implicit SGS model.…”

Section: Methodsmentioning

confidence: 99%

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

et al. 2015

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We employ a barotropic two-phase/two-fluid model to study the primary break-up of cavitating liquid jets emanating from a rectangular nozzle, which resembles a high aspect-ratio slot flow. All components (i.e., gas, liquid, and vapor) are represented by a homogeneous mixture approach. The cavitating fluid model is based on a thermodynamic-equilibrium assumption. Compressibility of all phases enables full resolution of collapse-induced pressure wave dynamics. The thermodynamic model is embedded into an implicit large-eddy simulation (LES) environment. The considered configuration follows the general setup of a reference experiment and is a generic reproduction of a scaled-up fuel injector or control valve as found in an automotive engine. Due to the experimental conditions, it operates, however, at significantly lower pressures. LES results are compared to the experimental reference for validation. Three different operating points are studied, which differ in terms of the development of cavitation regions and the jet break-up characteristics. Observed differences between experimental and numerical data in some of the investigated cases can be caused by uncertainties in meeting nominal parameters by the experiment. The investigation reveals that three main mechanisms promote primary jet break-up: collapse-induced turbulent fluctuations near the outlet, entrainment of free gas into the nozzle, and collapse events inside the jet near the liquid-gas interface. C 2015 AIP Publishing LLC. [http://dx

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Section: Methodsmentioning

confidence: 99%

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

et al. 2015

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“…This particular type of forcing has been adopted in previous studies [33,34] because it yields a −5/3 slope for the inertial range of the energy spectrum and is therefore more representative of Navier-Stokes turbulence. In what follows, this forcing approach is applied to the inviscid Burgers equation.…”

Section: Experiments In Burgers Turbulencementioning

confidence: 99%

Linear dispersion–diffusion analysis and its application to under-resolved turbulence simulations using discontinuous Galerkin spectral/hp methods

Moura

Sherwin

Peiró

2015

Journal of Computational Physics

145

109

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Please cite this article in press as: R.C. Moura et al., Linear dispersion-diffusion analysis and its application to under-resolved turbulence simulations using discontinuous Galerkin spectral/hp methods, J. Comput. Phys. (2015), http://dx.doi. org/10.1016/j.jcp.2015.06.020 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Linear dispersion-diffusion analysis and its application to under-resolved turbulence simulations using discontinuous Galerkin spectral/hp methods R.C. Moura, S.J. Sherwin 1 , J. PeiróWe investigate the potential of linear dispersion-diffusion analysis in providing direct guidelines for turbulence simulations through the under-resolved DNS (sometimes called implicit LES) approach via spectral/hp methods. The discontinuous Galerkin (DG) formulation is assessed in particular as a representative of these methods. We revisit the eigensolutions technique as applied to linear advection and suggest a new perspective on the role of multiple numerical modes, peculiar to spectral/hp methods. From this new perspective, "secondary" eigenmodes are seen to replicate the propagation behaviour of a "primary" mode, so that DG's propagation characteristics can be obtained directly from the dispersion-diffusion curves of the primary mode. Numerical dissipation is then appraised from these primary eigencurves and its effect over poorly-resolved scales is quantified. Within this scenario, a simple criterion is proposed to estimate DG's effective resolution in terms of the largest wavenumber it can accurately resolve in a given hp approximation space, also allowing us to present points per wavelength estimates typically used in spectral and finite difference methods. Although strictly valid for linear advection, the devised criterion is tested against (1D) Burgers turbulence and found to predict with good accuracy the beginning of the dissipation range on the energy spectra of under-resolved simulations. The analysis of these test cases through the proposed methodology clarifies why and how the DG formulation can be used for under-resolved turbulence simulations without explicit subgrid-scale modelling.In particular, when dealing with communication limited hardware which forces one to consider the performance for a fixed number of degrees of freedom, the use of higher polynomial orders along with moderately coarser meshes is shown to be the best way to translate available degrees of freedom into resolution power.

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“…An important example of this approach is known as MILES ͑monotonically integrated large-eddy simulation͒. 18 More recent developments 20 have indicated that the leading truncation error in certain discretization methods can be identified with certain explicit subgrid-scale models. This allows to implement and interpret the main contributions of this class of subgrid-scale models as part of the numerical modeling and is referred to as implicit modeling.…”

Section: Introductionmentioning

confidence: 99%

Numerically induced high-pass dynamics in large-eddy simulation

Geurts¹,

Bos²

2005

Physics of Fluids

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The numerical distortion of the smallest resolved-scale dynamics in large-eddy simulation may be understood in terms of the filter that is induced by the spatial discretization. At marginal subfilter resolution r = ⌬ / h, with filter width ⌬ and grid spacing h, the character of the large-eddy closure problem is strongly influenced by the numerical method. We show that additional high-pass contributions arise from the spatial discretization. The relative importance of, on the one hand, the turbulent stresses and, on the other hand, the numerically induced contributions, is quantified for general finite differencing methods. We derive and analyze the induced filters for several popular discretization methods, including higher order central and upwind methods. The application of these induced filters to small-scale turbulent flow structures gives rise to a characteristic amplitude reduction and phase shift. Their dynamic relevance is quantified in terms of the subfilter resolution. The numerical high-pass effects are found to be negligible if the subfilter resolution is large enough ͑r տ 4͒. Conversely, the numerically induced effects are comparable to, or even larger than the turbulent stresses as r =1-2.

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Implicit subgrid-scale modeling by adaptive deconvolution

Cited by 87 publications

References 33 publications

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

Large-eddy simulation of cavitating nozzle flow and primary jet break-up

Linear dispersion–diffusion analysis and its application to under-resolved turbulence simulations using discontinuous Galerkin spectral/hp methods

Numerically induced high-pass dynamics in large-eddy simulation

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