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Starting from limited measurements of a turbulent flow, data assimilation (DA) attempts to estimate all the spatio-temporal scales of motion. Success is dependent on whether the system is observable from the measurements, or how much of the…

Fluid Dynamics · Physics 2026-02-16 Andrew Cleary , Qi Wang , Tamer A. Zaki

Data-driven turbulence modeling is a newly emerged research area in thermal hydraulics simulation of nuclear power plant (NPP). The most common CFD method used in NPP thermal hydraulics simulation is Reynolds-averaged Navier-Stokes (RANS)…

Fluid Dynamics · Physics 2020-05-04 Yangmo Zhu , Nam Dinh

We propose a data-driven, closure model for Reynolds-averaged Navier-Stokes (RANS) simulations that incorporates aleatoric, model uncertainty. The proposed closure consists of two parts. A parametric one, which utilizes previously proposed,…

Fluid Dynamics · Physics 2024-04-16 Atul Agrawal , Phaedon-Stelios Koutsourelakis

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

Computational fluid dynamics using the Reynolds-averaged Navier-Stokes (RANS) remains the most cost-effective approach to study wake flows and power losses in wind farms. The underlying assumptions associated with turbulence closures are…

Fluid Dynamics · Physics 2022-08-03 Ali Eidi , Navid Zehtabiyan-Rezaie , Reza Ghiassi , Xiang Yang , Mahdi Abkar

We introduce a novel approach to derive compressibility corrections for Reynolds-averaged Navier-Stokes (RANS) models. Using this approach, we derive variable-property corrections for wall-bounded flows that take into account the distinct…

Fluid Dynamics · Physics 2025-09-17 Asif Manzoor Hasan , Alex Jose Elias , Florian Menter , Rene Pecnik

In atmospheric and turbulent flow modeling, Large Eddy Simulation (LES) is often used to reduce computational cost, while observational data typically originates from the underlying physical system. Motivated by this setting, we study a…

Analysis of PDEs · Mathematics 2025-08-12 Adam Larios , Ali Pakzad , Nicholas White

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

This study presents a compact data-driven Reynolds-averaged Navier-Stokes (RANS) model for wind turbine wake prediction, built as an enhancement of the standard \(k\)-\(\varepsilon\) formulation. Several candidate models were discovered…

Fluid Dynamics · Physics 2025-12-09 Kherlen Jigjid , Ali Eidi , Nguyen Anh Khoa Doan , Richard P. Dwight

A priori tests of turbulence models for the compressible Reynolds-Averaged Navier--Stokes (RANS) are performed by using Direct Numerical Simulations (DNS) data of zero-pressure-gradient flat-plate turbulent boundary layers. The DNS database…

Fluid Dynamics · Physics 2023-10-17 Sciacovelli L. , Cannici A. , Passiatore D. , Cinnella P

Reynolds-averaged Navier--Stokes (RANS) simulations with turbulence closure models continue to play important roles in industrial flow simulations. However, the commonly used linear eddy viscosity models are intrinsically unable to handle…

Fluid Dynamics · Physics 2019-05-22 Jin-Long Wu , Heng Xiao , Rui Sun , Qiqi Wang

We study a continuous data assimilation (CDA) algorithm for a velocity-vorticity formulation of the 2D Navier-Stokes equations in two cases: nudging applied to the velocity and vorticity, and nudging applied to the velocity only. We prove…

Numerical Analysis · Mathematics 2020-06-15 Matthew Gardner , Adam Larios , Leo G. Rebholz , Duygu Vargun , Camille Zerfas

A non-intrusive data assimilation methodology is developed to improve the statistical predictions of large-eddy simulations (LES). The ensemble-variational (EnVar) approach aims to minimize a cost function that is defined as the discrepancy…

Fluid Dynamics · Physics 2021-09-28 Vincent Mons , Yifan Du , Tamer A. Zaki

We solve a Bayesian inverse Reynolds-averaged Navier-Stokes (RANS) problem that assimilates mean flow data by jointly reconstructing the mean flow field and learning its unknown RANS parameters. We devise an algorithm that learns the most…

Fluid Dynamics · Physics 2024-12-17 A. Kontogiannis , P. Nair , M. Loecher , D. B. Ennis , A. Marsden , M. P. Juniper

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

Reynolds-averaged Navier--Stokes (RANS) closure must be sensitive to the flow physics, including nonlocality and anisotropy of the effective eddy viscosity. Recent approaches used forced direct numerical simulations to probe these effects,…

Fluid Dynamics · Physics 2024-09-24 Jessie Liu , Florian Schäfer , Spencer H. Bryngelson , Tamer A. Zaki , Ali Mani

Extending gradient-type turbulence closures to turbulent premixed flames is challenging due to the significant influence of combustion heat release. We incorporate a deep neural network (DNN) into Reynolds-averaged Navier--Stokes (RANS)…

Fluid Dynamics · Physics 2025-06-18 Priyesh Kakka , Jonathan F. MacArt

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

Accurate simulation of turbulent flows remains a challenge due to the high computational cost of direct numerical simulations (DNS) and the limitations of traditional turbulence models. This paper explores a novel approach to augmenting…

Fluid Dynamics · Physics 2025-02-17 Jonas Luther , Patrick Jenny

Despite their well-known limitations, Reynolds-Averaged Navier-Stokes (RANS) models are still the workhorse tools for turbulent flow simulations in today's engineering application. For many practical flows, the turbulence models are by far…

Computational Physics · Physics 2018-09-11 H. Xiao , J. -L. Wu , J. -X. Wang , R. Sun , C. J. Roy