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We introduce a data-driven learning framework that assimilates two powerful ideas: ideal large eddy simulation (LES) from turbulence closure modeling and neural stochastic differential equations (SDE) for stochastic modeling. The ideal LES…

Mechanisms are designed to perform functions in various fields. Often, there is no unique mechanism that performs a well-defined function. For example, vehicle suspensions are designed to improve driving performance and ride comfort, but…

Computational Physics · Physics 2025-05-26 Sumin Lee , Namwoo Kang

In typical nature and engineering scenarios, such as supernova explosion and inertial confinement fusion, mixing flows induced by hydrodynamics interfacial instabilities are essentially compressible. Despite their significance, accurate…

Fluid Dynamics · Physics 2025-06-23 Hansong Xie , Tengfei Luo , Yaomin Zhao , Yousheng Zhang , Jianchun Wang

Data assimilation (DA) plays a crucial role in extracting valuable information from flow measurements in fluid dynamics problems. Often only time-averaged data is available, which poses challenges for DA in the context of unsteady flow…

Fluid Dynamics · Physics 2024-05-30 Justin Plogmann , Oliver Brenner , Patrick Jenny

A new approach to turbulence simulation, based on a combination of large-eddy simulation (LES) for the whole flow and an array of non-space-filling quasi-direct numerical simulations (QDNS), which sample the response of near-wall turbulence…

Fluid Dynamics · Physics 2017-10-20 Neil D. Sandham , Roderick Johnstone , Christian T. Jacobs

Multi-fidelity optimization employs surrogate models that integrate information from varying levels of fidelity to guide efficient exploration of complex design spaces while minimizing the reliance on (expensive) high-fidelity objective…

Multi-fidelity machine learning methods address the accuracy-efficiency trade-off by integrating scarce, resource-intensive high-fidelity data with abundant but less accurate low-fidelity data. We propose a practical multi-fidelity strategy…

Machine Learning · Computer Science 2025-03-26 Jiaxiang Yi , Ji Cheng , Miguel A. Bessa

Use of appropriate initialization to warm-start Reynolds-averaged Navier-Stokes (RANS) simulations of turbulent flow can facilitate convergence and lead to efficient use of computational resources. In this work, a method to model downstream…

Fluid Dynamics · Physics 2025-01-27 Kazuko W. Fuchi , Eric M. Wolf , Christopher R. Schrock , Philip S. Beran

Computational fluid dynamics (CFD) solvers employing two-equation eddy viscosity models are the industry standard for simulating turbulent flows using the Reynolds-averaged Navier-Stokes (RANS) formulation. While these methods are…

Machine Learning · Computer Science 2024-10-25 Shinjan Ghosh , Amit Chakraborty , Georgia Olympia Brikis , Biswadip Dey

Deep reinforcement learning (DRL) is a promising outer-loop intelligence paradigm which can deploy problem solving strategies for complex tasks. Consequently, DRL has been utilized for several scientific applications, specifically in cases…

Machine Learning · Computer Science 2023-04-05 Sahil Bhola , Suraj Pawar , Prasanna Balaprakash , Romit Maulik

Within the context of machine learning-based closure mappings for RANS turbulence modelling, physical realizability is often enforced using ad-hoc postprocessing of the predicted anisotropy tensor. In this study, we address the…

Fluid Dynamics · Physics 2025-08-05 Ryley McConkey , Nikhila Kalia , Eugene Yee , Fue-Sang Lien

This study proposes a novel method for developing discretization-consistent closure schemes for implicitly filtered Large Eddy Simulation (LES). Here, the induced filter kernel, and thus the closure terms, are determined by the properties…

Fluid Dynamics · Physics 2023-12-14 Andrea Beck , Marius Kurz

Robust controllers that stabilize dynamical systems even under disturbances and noise are often formulated as solutions of nonsmooth, nonconvex optimization problems. While methods such as gradient sampling can handle the nonconvexity and…

Optimization and Control · Mathematics 2023-05-01 Steffen W. R. Werner , Michael L. Overton , Benjamin Peherstorfer

This paper proposes a phenomenological Reynolds Averaged Navier-Stokes (RANS) calculation model based on physical constraints. In this model part of the source terms in the e equation was replaced with the deep learning model, using the…

Fluid Dynamics · Physics 2021-12-28 Shuming Zhang , Haiwang Li , Ruquan You , Tinglin Kong , Zhi Tao

High-order methods and hybrid turbulence models have independently shown promise as means of decreasing the computational cost of scale-resolving simulations. The objective of this work is to develop the combination of these methods and…

Fluid Dynamics · Physics 2022-01-26 Tarik Dzanic , Sharath Girimaji , Freddie Witherden

Hybrid physics-machine learning models are increasingly being used in simulations of transport processes. Many complex multiphysics systems relevant to scientific and engineering applications include multiple spatiotemporal scales and…

Fluid Dynamics · Physics 2021-06-09 Shady E. Ahmed , Omer San , Kursat Kara , Rami Younis , Adil Rasheed

Generally, reduced order models of fluid flows are obtained by projecting the Navier-Stokes equations onto a reduced subspace spanned by vector functions that carry the meaningful information of the dynamics. A common method to generate…

Fluid Dynamics · Physics 2023-09-22 M. Oulghelou , A. Ammar , R. Ayoub

High-fidelity scale-resolving simulations of turbulent flows quickly become prohibitively expensive, especially at high Reynolds numbers. As a remedy, we may use multifidelity models (MFM) to construct predictive models for flow quantities…

Fluid Dynamics · Physics 2023-06-14 Saleh Rezaeiravesh , Timofey Mukha , Philipp Schlatter

A common goal throughout science and engineering is to solve optimization problems constrained by computational models. However, in many cases a high-fidelity numerical emulation of systems cannot be optimized due to code complexity and…

Numerical Analysis · Mathematics 2023-05-31 Joseph Hart , Bart van Bloemen Waanders

The accuracy of coarse-grained continuum models of dense granular flows is limited by the lack of high-fidelity closure models for granular rheology. One approach to addressing this issue, referred to as the hierarchical multiscale method,…

Soft Condensed Matter · Physics 2025-09-30 B. Siddani , Weiqun Zhang , Andrew Nonaka , John Bell , Ishan Srivastava