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Understanding the coolant thermal hydraulics in rod bundles is essential to the design of nuclear reactors. However, flows with low Reynolds numbers present serious modeling challenges, especially in heat transfer and natural convection.…

Fluid Dynamics · Physics 2023-08-31 Carolina Bourdot Dutra , Elia Merzari

Direct numerical simulations (DNS) are one of the main ab initio tools to study turbulent flows. However, due to their considerable computational cost, DNS are primarily restricted to canonical flows at moderate Reynolds numbers, in which…

Fluid Dynamics · Physics 2024-09-17 Arnab Moitro , Sai Sandeep Dammati , Alexei Y. Poludnenko

Turbulent flow over a surface with streamwise-elongated rough and smooth stripes is studied by means of direct numerical simulation (DNS) in a periodic plane open channel with fully resolved roughness. The goal is to understand how the mean…

Fluid Dynamics · Physics 2021-09-23 A. Stroh , K. Schäfer , B. Frohnapfel , P. Forooghi

Within the domain of Computational Fluid Dynamics, Direct Numerical Simulation (DNS) is used to obtain highly accurate numerical solutions for fluid flows. However, this approach for numerically solving the Navier-Stokes equations is…

Fluid Dynamics · Physics 2021-03-16 Pranshu Pant , Amir Barati Farimani

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

Direct Numerical Simulations are used to solve turbulent flow and heat transfer over a variety of rough walls in a channel. The wall geometries are exactly resolved in the simulations. The aim is to understand the effect of roughness…

Fluid Dynamics · Physics 2018-06-25 Pourya Forooghi , Matthias Stripf , Bettina Frohnapfel

A fully-resolved direct-numerical-simulation (DNS) approach for investigating flexible bodies forced by a turbulent incoming flow is designed to study the flapping motion of a flexible flag at moderate Reynolds number. The incoming…

Fluid Dynamics · Physics 2021-08-25 Stefano Olivieri , Francesco Viola , Andrea Mazzino , Marco E. Rosti

We perform direct numerical simulations (DNS) of a turbulent channel flow over porous walls. In the fluid region the flow is governed by the incompressible Navier--Stokes (NS) equations, while in the porous layers the Volume-Averaged…

Fluid Dynamics · Physics 2023-07-19 Marco E. Rosti , Luca Cortelezzi , Maurizio Quadrio

To fully evaluate a turbulent flow, Direct Numerical Simulation (DNS) is the most accurate method by far and requires considerable computational power and time; not optimum for industry standards. Developing an alternative model, providing…

Fluid Dynamics · Physics 2022-07-04 Indrajit Nandi , Saikat Saha , Sabir Subedi , Sumon Saha

Direct Numerical Simulations (DNS) of turbulent channel flow at a shear Reynolds number of $Re_{*}=360$ for Newtonian and Herschel-Bulkley fluids in smooth and rough channels has been performed. The rough surface was made of irregular…

Fluid Dynamics · Physics 2023-12-11 C. Narayanan , S. Nauer , J. -S. Singh , R. Belt , T. Palermo , D. Lakehal

Direct numerical simulations (DNS) are performed to study the turbulent shear flow of an electrically conducting fluid in a cylindrical container. The flow is driven by the interaction between the radial electric currents ($I$) injected…

Fluid Dynamics · Physics 2021-04-21 Long Chen , Alban Pothérat , Ming-Jiu Ni , René Moreau

Numerical simulation of fluids plays an essential role in modeling many physical phenomena, which enables technological advancements, contributes to sustainable practices, and expands our understanding of various natural and engineered…

The precise simulation of turbulent flows holds immense significance across various scientific and engineering domains, including climate science, freshwater science, and energy-efficient manufacturing. Within the realm of simulating…

Fluid Dynamics · Physics 2024-12-31 Shengyu Chen , Peyman Givi , Can Zheng , Xiaowei Jia

We present a new spectral method for the Direct Numerical Simulation of Magnetohydrodynamic turbulence at low Magnetic Reynolds number. The originality of our approach is that instead of using traditional bases of functions, it relies on…

Fluid Dynamics · Physics 2011-11-15 Alban Pothérat , Vitali Dymkou

The multiscale nature of turbulent combustion necessitates accurate and computationally efficient methods for direct numerical simulations (DNS). The field has long been dominated by high-order finite differences, which lack the flexibility…

Fluid Dynamics · Physics 2024-01-24 Jack R. C. King

Direct numerical simulations (DNS) are performed for two wall-bounded flow configurations: laminar Couette flow at $Re=740$ and turbulent channel flow at $Re_{\tau}=180$, where $\tau$ is the shear stress at the wall. The top wall is smooth…

Fluid Dynamics · Physics 2019-07-22 Karim Alamé , Krishnan Mahesh

Computational modeling of charged species transport has enabled the analysis, design, and optimization of a diverse array of electrochemical and electrokinetic devices. These systems are represented by the Poisson-Nernst-Planck (PNP)…

Numerical Analysis · Mathematics 2024-01-02 Sungu Kim , Kumar Saurabh , Makrand A. Khanwale , Ali Mani , Robbyn K. Anand , Baskar Ganapathysubramanian

Understanding the influence of surface roughness on drag forces remains a significant challenge in fluid dynamics. This paper presents a convolutional neural network (CNN) that predicts drag solely by the topography of rough surfaces and is…

This review focuses on Direct numerical simulations (DNS) of turbulent flows laden with droplets or bubbles. DNS of these flows are more challenging than those of flows laden with solid particles due to the surface deformation in the…

Fluid Dynamics · Physics 2018-04-10 Said Elghobashi

We present a novel computational method for direct numerical simulations of particle-laden flows with fully-resolved particles (PR-DNS). The method is based on the recently developed Volume-Filtering Immersed Boundary method [Dave et al,…

Fluid Dynamics · Physics 2024-05-01 M. Houssem Kasbaoui , Marcus Herrmann