Importance of Sub-Grid Scale Modeling for Accurate Aerodynamic Simulations

Ekman, Petter; Venning, James A.; Virdung, Torbjörn; Karlsson, Matts

doi:10.1115/1.4048351

Cited by 11 publications

(2 citation statements)

References 50 publications

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“…Recently Ekman et al [21] reported WRLES simulations of the Ahmed 25° car model at a Reynolds number of 𝑅𝑒 𝐻 = 0.26 • 10 6 . They used two hexahedral grids with 33.8 and 55.3 million cells and investigated three subgrid models.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulations for the Ahmed Car at 25° Slant Angle at Different Reynolds Numbers

Menter,

Hüppe,

Flad

et al. 2023

Flow Turbulence Combust

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The article investigates the feasibility of Large Eddy Simulation methods to accurately compute the flow around the Ahmed car body at 25° slant angle. The flow is computed at two different Reynolds numbers and with different turbulence modeling concepts using a large variety of grids. Issues associated with the accurate computation of the separation at the slant onset will be discussed in detail.

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Section: Introductionmentioning

confidence: 99%

Large Eddy Simulations for the Ahmed Car at 25° Slant Angle at Different Reynolds Numbers

Menter,

Hüppe,

Flad

et al. 2023

Flow Turbulence Combust

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“…meteorology (Müller & Scherer 2005)) and engineering (e.g. aerodynamics (Ekman et al 2020)). The specific case of magnetized fluids comes with its own challenges, mostly related to the problem of the emergence of inverse cascades.…”

Section: Introductionmentioning

confidence: 99%

Assessment of a new sub-grid model for magnetohydrodynamical turbulence. I. Magnetorotational instability

Miravet-Tenés

Cerdá–Durán

Obergaulinger

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Insufficient numerical resolution of grid-based, direct numerical simulations (DNS) hampers the development of instability-driven turbulence at small (unresolved) scales. As an alternative to DNS, sub-grid models can potentially reproduce the effects of turbulence at small scales in terms of the resolved scales, and hence can capture physical effects with less computational resources. We present a new sub-grid model, the MHD-instability-induced-turbulence (MInIT) mean-field model. MInIT is a physically motivated model based on the evolution of the turbulent (Maxwell, Reynolds, and Faraday) stress tensors and their relation with the turbulent energy densities of the magneto-rotational (MRI) and parasitic instabilities, modeled with two partial differential evolution equations with stiff source terms. Their solution allows obtaining the turbulent stress tensors through the constant coefficients that link them to the energy densities. The model is assessed using data from MRI in-box DNS and applying a filtering operation to compare the filtered data with that from the model. Using the L2-norm as the metric for the comparison, we find less than one order-of-magnitude difference between the two sets of data. No dependence on filter size or length scale of unresolved scales is found, as opposed to results using the gradient model (which we also use to contrast our model) in which the L2-norm of some of the stresses increases with filter size. We conclude that MInIT can help DNS by properly capturing small-scale turbulent stresses which has potential implications on the dynamics of highly-magnetized rotating compact objects, such as those formed during binary neutron star mergers.

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Verification and Validation for Large Eddy Simulation of Cavitating Flow Around a Projectile Near the Free Surface

Deng,

Long,

Cheng

et al. 2024

J. Marine. Sci. Appl.

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Verification and validation (V&V) is a helpful tool for evaluating simulation errors, but its application in unsteady cavitating flow remains a challenging issue due to the difficulty in meeting the requirement of an asymptotic range. Hence, a new V&V approach for large eddy simulation (LES) is proposed. This approach offers a viable solution for the error estimation of simulation data that are unable to satisfy the asymptotic range. The simulation errors of cavitating flow around a projectile near the free surface are assessed using the new V&V method. The evident error values are primarily dispersed around the cavity region and free surface. The increasingly intense cavitating flow increases the error magnitudes. In addition, the modeling error magnitudes of the Dynamic Smagorinsky–Lilly model are substantially smaller than that of the Smagorinsky–Lilly model. The present V&V method can capture the decrease in the modeling errors due to model enhancements, further exhibiting its applicability in cavitating flow simulations. Moreover, the monitoring points where the simulation data are beyond the asymptotic range are primarily dispersed near the cavity region, and the number of such points grows as the cavitating flow intensifies. The simulation outcomes also suggest that the re-entrant jet and shedding cavity collapse are the chief sources of vorticity motions, which remarkably affect the simulation accuracy. The results of this study provide a valuable reference for V&V research.

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Importance of Sub-Grid Scale Modeling for Accurate Aerodynamic Simulations

Cited by 11 publications

References 50 publications

Large Eddy Simulations for the Ahmed Car at 25° Slant Angle at Different Reynolds Numbers

Large Eddy Simulations for the Ahmed Car at 25° Slant Angle at Different Reynolds Numbers

Assessment of a new sub-grid model for magnetohydrodynamical turbulence. I. Magnetorotational instability

Verification and Validation for Large Eddy Simulation of Cavitating Flow Around a Projectile Near the Free Surface

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