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The Reynolds-averaged Navier-Stokes (RANS) equations are widely used in turbulence applications. They require accurately modeling the anisotropic Reynolds stress tensor, for which traditional Reynolds stress closure models only yield…

Fluid Dynamics · Physics 2022-03-23 Haitz Sáez de Ocáriz Borde , David Sondak , Pavlos Protopapas

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

The partially-averaged Navier-Stokes (PANS) equations are used to predict the variable-density Rayleigh-Taylor (RT) flow at Atwood number 0.5 and maximum Reynolds number $500$. This is a prototypical problem of material mixing featuring…

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

The development of turbulence closure models, parametrizing the influence of small non-resolved scales on the dynamics of large resolved ones, is an outstanding theoretical challenge with vast applicative relevance. We present a closure,…

Fluid Dynamics · Physics 2024-06-26 Giulio Ortali , Alessandro Corbetta , Gianluigi Rozza , Federico Toschi

This proposed work introduces a data-assimilation-assisted approach to train neural networks, aimed at effectively reducing epistemic uncertainty in state estimates of separated flows. This method, referred to as model-consistent training,…

Fluid Dynamics · Physics 2024-08-02 Minghan Chu

The design of film cooling systems relies heavily on Reynolds-Averaged Navier-Stokes (RANS) simulations, which solve for mean quantities and model all turbulent scales. Most turbulent heat flux models, which are based on isotropic diffusion…

Fluid Dynamics · Physics 2019-10-09 Pedro M. Milani , Julia Ling , John K. Eaton

Turbulence modeling is a critical component in numerical simulations of industrial flows based on Reynolds-averaged Navier-Stokes (RANS) equations. However, after decades of efforts in the turbulence modeling community, universally…

Fluid Dynamics · Physics 2017-03-22 Jian-Xun Wang , Jin-Long Wu , Heng Xiao

A central obstacle to understanding the route to turbulence in wall-bounded flows is that the flows are composed of complex, highly fluctuating, and strongly nonlinear states. In the case of pipe flow, models have deepened our understanding…

Fluid Dynamics · Physics 2026-02-24 Santiago J. Benavides , Dwight Barkley

Lagrangian particle tracking is essential for characterizing turbulent flows, but inferring particle acceleration from inherently noisy position data remains a significant challenge. Fluid particles in turbulence experience extreme,…

Data Analysis, Statistics and Probability · Physics 2026-02-27 Griffin M Kearney , Kasey M Laurent , Makan Fardad

Multi-fidelity optimization methods promise a high-fidelity optimum at a cost only slightly greater than a low-fidelity optimization. This promise is seldom achieved in practice, due to the requirement that low- and high-fidelity models…

Computational Physics · Physics 2021-01-29 Yu Zhang , Richard P. Dwight , Martin Schmelzer , Javier F. Gomez , Stefan Hickel , Zhong-hua Han

The Reynolds-averaged Navier-Stokes (RANS) equations require accurate modeling of the anisotropic Reynolds stress tensor. Traditional closure models, while sophisticated, often only apply to restricted flow configurations. Researchers have…

Fluid Dynamics · Physics 2022-02-02 Haitz Sáez de Ocáriz Borde , David Sondak , Pavlos Protopapas

This study proposes a global similarity correction for Reynolds-averaged Navier--Stokes (RANS) modeling of buoyancy effects in unstably stratified flows. Conventional two-equation RANS models (e.g., the $k$-$\varepsilon$ model) lack a clear…

Fluid Dynamics · Physics 2025-03-14 Da-Sol Joo

Despite the increasing availability of high-performance computational resources, Reynolds-Averaged Navier-Stokes (RANS) simulations remain the workhorse for the analysis of turbulent flows in real-world applications. Linear eddy viscosity…

Fluid Dynamics · Physics 2023-11-27 Leon Riccius , Atul Agrawal , Phaedon-Stelios Koutsourelakis

Reynolds-averaged Navier-Stokes (RANS)-based transition modeling is widely used in aerospace applications but suffers inaccuracies due to the Boussinesq turbulent viscosity hypothesis. The eigenspace perturbation method can estimate the…

Fluid Dynamics · Physics 2022-11-08 Minghan Chu , Weicheng Qian

This paper presents a novel methodology for the direct numerical modeling and simulation of turbulent flows. The kinetic model equation is firstly extended to turbulent flow with the account of coupled evolution of kinetic, thermal, and…

Computational Physics · Physics 2025-03-11 Xiaojian Yang , Kun Xu

In this paper, we propose normalizing flows (NF) as a novel probability density function (PDF) turbulence model (NF-PDF model) for the Reynolds-averaged Navier-Stokes (RANS) equations. We propose to use normalizing flows in two different…

Fluid Dynamics · Physics 2021-01-12 Deniz A. Bezgin , Nikolaus A. Adams

It has previously been shown that by increasing the Reynolds number across a channel by spatially varying the viscosity does not cause an immediate change in the size of turbulent structures and a delay is in fact observed in both wall…

Fluid Dynamics · Physics 2021-06-11 Victor Coppo Leite , Elia Merzari

Cavitation is a complex multiphase phenomenon characterised by vapour bubbles forming due to a sudden pressure drop and is often accompanied by increased hull vibrations, increased radiated noise and decrease in propeller and impeller…

Fluid Dynamics · Physics 2024-05-02 Dhruv Apte , Mingming Ge , Olivier Coutier-Delgosha

Predictive simulation of many complex flows requires moving beyond Reynolds-averaged Navier-Stokes (RANS) based models to representations resolving at least some scales of turbulence in at least some regions of the flow. To resolve…

Fluid Dynamics · Physics 2018-12-11 Sigfried Haering , Todd A. Oliver , Robert D. Moser