Large eddy simulations in 2030 and beyond

Piomelli, Ugo

doi:10.1098/rsta.2013.0320

Cited by 62 publications

(23 citation statements)

References 47 publications

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“…This has allowed us to compare the available results for 2D turbulent periodic boxes 76,[87][88][89] . 2 We consider a square domain with x, y both in the range [−L/2, L/2] with N points in each direction. The initial positions of the mixing layers are y = ±L/4, as the initial set-up describes:…”

Section: Periodic 2d Kelvin Helmholtz Testsmentioning

confidence: 99%

Extension of the subgrid-scale gradient model for compressible magnetohydrodynamics turbulent instabilities

2019

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Performing accurate large eddy simulations in compressible, turbulent magnetohydrodynamics is more challenging than in non-magnetized fluids due to the complex interplay between kinetic, magnetic and internal energy at different scales. Here we extend the sub-grid-scale gradient model, so far used in the momentum and induction equations, to account also for the unresolved scales in the energy evolution equation of a compressible ideal MHD fluid with a generic equation of state. We assess the model by considering box simulations of the turbulence triggered across a shear layer by the Kelvin-Helmholtz instability, testing cases where the small-scale dynamics cannot be fully captured by the resolution considered, such that the efficiency of the simulated dynamo effect depends on the resolution employed. This lack of numerical convergence is actually a currently common issue in several astrophysical problems, where the integral and fastest-growing-instability scales are too far apart to be fully covered numerically. We perform a-priori and a-posteriori tests of the extended gradient model. In the former, we find that, for many different initial conditions and resolutions, the gradient model outperforms other commonly used models in terms of correlation with the residuals coming from the filtering of a high-resolution run. In the second test, we show how a low-resolution run with the gradient model is able to quantitatively reproduce the evolution of the magnetic energy (the integrated value and the spectral distribution) coming from higher-resolution runs. This extension is the first step towards the implementation in relativistic magnetohydrodynamics.

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Section: Periodic 2d Kelvin Helmholtz Testsmentioning

confidence: 99%

Extension of the subgrid-scale gradient model for compressible magnetohydrodynamics turbulent instabilities

2019

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“…In LES large scales of motion are resolved directly, while small scales must be modeled with an appropriate subgrid-scale (SGS) model. The overview and outlook of LES could be found in [8]. LES, being an eddy-resolving technique, requires for large computational resources.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of mean velocity and mean speed for test ventilated room from RANS and LES CFD modeling

et al. 2019

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The paper presents and discusses data for the ventilation airflow in an isothermal room corresponding to the Nielsen et al. (1978) test computed with Large Eddy Simulation (LES) and Reynolds-Averaged Navier-Stokes (RANS) approaches. As LES computations provide directly both the speed and velocity components data, the difference between the mean speed and mean velocity values is computed and discussed. For the RANS computations that give the mean velocity data only, application of the velocity-to-speed conversion procedure based on the turbulence kinetic energy field provided by a turbulence model resulted in accurate mean speed evaluation.

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“…LES could provide inaccurate results if effects of small scale turbulent structures are not appropriately modeled. Therefore, development of advanced models for the unresolved scales that adapt to the local flow conditions and the hybridization of LES with the solution of the Reynolds-averaged Navier-Stokes equations is still an active research area [27].…”

Section: Introductionmentioning

confidence: 99%

Assessment of predictive capability of hybrid URANS/LES methods in residence time calculation

Mehdizadeh

Doost

Sadiki

et al. 2018

Chemical Engineering Science

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The present study aims to assess capability of mostly used hybrid URANS/LES methods in dealing with a complex swirled configuration/reactor when the residence time characteristics need to be predicted at acceptable level of accuracy and fidelity. The configuration is quite complex and out of reach of the classical RANS turbulence models as it consists of different, partly swirled inlet channels and a large variety of time and length scales. In this work only the flow field is considered and is investigated using three different hybrid URANS/LES simulation methods. The models: the Scale Adaptive Simulation (SAS), the Improved Delayed Detached Eddy Simulation(SA-IDDES) and the k − ω − DES, use different triggering mechanisms and underlying RANS models. The results of the flow field, the residence time characteristics and all related quantities are compared with both the Large Eddy Simulation (LES) and experimental data reported in Doost et.al [17]. It turns out that none of the considered hybrid methods is able to predict the residence time characteristics as well as LES does mainly due to the inaccurate prediction of the flow field. It was found that there is a need to improve the hybrid approaches by addressing the shortcomings, particularly those regarding triggering mechanism to make hybrid approaches a reliable computational tool for study complex turbulent flows inside full scale configurations where LES can be prohibitively expensive.

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Large eddy simulations in 2030 and beyond

Cited by 62 publications

References 47 publications

Extension of the subgrid-scale gradient model for compressible magnetohydrodynamics turbulent instabilities

Extension of the subgrid-scale gradient model for compressible magnetohydrodynamics turbulent instabilities

Evaluation of mean velocity and mean speed for test ventilated room from RANS and LES CFD modeling

Assessment of predictive capability of hybrid URANS/LES methods in residence time calculation

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