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Neural network subgrid stress models often have a priori performance that is far better than the a posteriori performance, leading to neural network models that look very promising a priori completely failing in a posteriori Large Eddy…

Fluid Dynamics · Physics 2025-11-24 Andy Wu , Sanjiva K. Lele

We developed a novel autonomously dynamic nonlocal turbulence model for the large and very large eddy simulation (LES, VLES) of the homogeneous isotropic turbulent flows (HIT). The model is based on a generalized (integer-to-noninteger)…

Fluid Dynamics · Physics 2022-03-07 S. Hadi Seyedi , Mohsen Zayernouri

This study proposes a rotationally invariant data-driven subgrid-scale (SGS) model for large-eddy simulation (LES) of wall-bounded turbulent flows. Building upon the multiscale convolutional neural network subgrid-scale model, which outputs…

Fluid Dynamics · Physics 2026-02-03 Bahrul Jalaali , Kie Okabayashi

The predictive accuracy of wall-modelled LES is influenced by a combination of the subgrid model, the wall model, the numerical dissipation induced primarily by the convective numerical scheme, and also by the density and topology of the…

Fluid Dynamics · Physics 2020-09-02 Timofey Mukha , Rickard E. Bensow , Mattias Liefvendahl

Accurate subgrid-scale turbulence models are needed to perform realistic numerical magnetohydrodynamic (MHD) simulations of the subsurface flows of the Sun. To perform large-eddy simulations (LES) of turbulent MHD flows, three unknown terms…

Solar and Stellar Astrophysics · Physics 2010-10-28 G. Balarac , A. G. Kosovichev , O. Brugière , A. A. Wray , N. N. Mansour

We introduce a novel recursive process to a neural-network-based subgrid-scale (NN-based SGS) model for large eddy simulation (LES) of high Reynolds number turbulent flow. This process is designed to allow an SGS model to be applicable to a…

Fluid Dynamics · Physics 2024-12-04 Chonghyuk Cho , Jonghwan Park , Haecheon Choi

Extensive experimental evidence highlight that scalar turbulence exhibits anomalous diffusion and stronger intermittency levels at small scales compared to that in fluid turbulence. This renders the corresponding subgrid-scale dynamics…

Fluid Dynamics · Physics 2024-06-19 S. Hadi Seyedi , Ali Akhavan-Safaei , Mohsen Zayernouri

Even though compressible plasma turbulence is encountered in many astrophysical phenomena, its effect is often not well understood. Furthermore, direct numerical simulations are typically not able to reach the extreme parameters of these…

Fluid Dynamics · Physics 2016-07-27 P. Grete , D. G. Vlaykov , W. Schmidt , D. R. G. Schleicher

A nonlocal subgrid-scale stress (SGS) model is developed based on the convolution neural network (CNN), a powerful supervised data-driven approach. The CNN is an ideal approach to naturally consider nonlocal spatial information in…

Fluid Dynamics · Physics 2023-01-27 Bo Liu , Huiyang Yu , Haibo Huang , Xi-Yun Lu

Current design constraints have encouraged the studies of aeroacoustics fields around compressible jet flows. The present work addresses the numerical study of subgrid scale modeling for unsteady turbulent jet flows as a preliminary step…

Fluid Dynamics · Physics 2023-01-03 Carlos Junqueira-Junior , Sami Yamouni , Joao Luiz F. Azevedo , William Wolf

In this article, we utilize machine learning to dynamically determine if a point on the computational grid requires implicit numerical dissipation for large eddy simulation (LES). The decision making process is learnt through \emph{a…

Fluid Dynamics · Physics 2019-02-07 Romit Maulik , Omer San , Jamey D Jacob

Neural networks of simple structures are used to construct a turbulence model for large-eddy simulation (LES). Data obtained by direct numerical simulation (DNS) of homogeneous isotropic turbulence are used to train neural networks. It is…

Fluid Dynamics · Physics 2020-12-04 Satoshi Miyazaki , Yuji Hattori

Large Eddy Simulations (LES) are becoming increasingly viable due to the growth in computational power the last few decades, and subgrid stress modelling plays a large role in the accuracy of LES. A new class of neural network models, S4…

Fluid Dynamics · Physics 2025-11-17 Andy Wu , Sanjiva K. Lele

In this review, the methodology of large eddy simulations (LES) is introduced and applications in astrophysics are discussed. As theoretical framework, the scale decomposition of the dynamical equations for neutral fluids by means of…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-10 Wolfram Schmidt

Filtering the passive scalar transport equation in the large-eddy simulation (LES) of turbulent transport gives rise to the closure term corresponding to the unresolved scalar flux. Understanding and respecting the statistical features of…

Fluid Dynamics · Physics 2021-07-12 Ali Akhavan-Safaei , Mehdi Samiee , Mohsen Zayernouri

Large eddy simulation (LES) of forced, homogeneous, isotropic, two-dimensional (2D) turbulence in the energy transfer subrange is the subject of this paper. A difficulty specific to this LES and its subgrid scale (SGS) representation is in…

chao-dyn · Physics 2008-02-03 Semion Sukoriansky , Alexei Chekhlov , Boris Galperin , Steven A. Orszag

A computational domain translation velocity is often used in LES simulations to improve computational performance by allowing longer time-step intervals. Even though the equations of motion are Galilean invariant, LES results have been…

Atmospheric and Oceanic Physics · Physics 2019-07-15 Oumaima Lamaakel , Georgios Matheou

Large Eddy Simulation (LES) is a very useful tool when simulating turbulent flows if we are only interested in its "larger" scales. One of the possible ways to derive the LES equations is to apply a filter operator to the Navier-Stokes…

Analysis of PDEs · Mathematics 2017-03-14 José M. Rodríguez , Raquel Taboada-Vázquez

The results of large eddy simulation (LES) using three sub-grid scale models, namely: constant coefficient Smagorinsky, dynamic Smagorinsky, and a dynamic Clark model, for rotating stratified turbulence in the absence of forcing using…

Fluid Dynamics · Physics 2023-08-17 Kiran Jadhav , Rahul Agrawal , Abhilash J. Chandy

Rotating turbulent flows form a challenging test case for large-eddy simulation (LES). We, therefore, propose and validate a new subgrid-scale (SGS) model for such flows. The proposed SGS model consists of a dissipative eddy viscosity term…

Fluid Dynamics · Physics 2019-04-30 Maurits H. Silvis , H. Jane Bae , F. Xavier Trias , Mahdi Abkar , Roel Verstappen