Article
Physics, Fluids & Plasmas
Jun Hu
Summary: This study examines the linear global stability of a downward flow of liquid metal in a vertical duct under strong wall heating and a transverse magnetic field through numerical methods. The results show that the elevator mode is consistently unstable, while the unstable oscillatory mode is directly related to the specific flow structure with upward reverse flow.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Physics, Nuclear
Giuliano Giacalone, Chun Shen
Summary: The study shows that event-shape engineering based on the mean transverse momentum of charged hadrons provides an optimal handle on the strength of the magnetic field in central heavy-ion collisions. Quantitative evaluations reveal a correlation between the event-by-event magnetic field and [p(t)]. The new method offers advantages for the experimental search of the chiral magnetic effect.
EUROPEAN PHYSICAL JOURNAL A
(2021)
Article
Mechanics
Fan Xu, Jinghong Su, Bin Lan, Peng Zhao, Yurong He, Chao Sun, Junwu Wang
Summary: The study demonstrates that the clockwise rotation of vertically asymmetric rough wall can significantly enhance the torque of the Taylor-Couette flow at high Taylor numbers, compared to counter-clockwise rotation. Meanwhile, the rotating direction has a negligible effect on the torque at low Taylor numbers.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Thermodynamics
V. I. Artemov, M. V. Makarov, G. G. Yankov, K. B. Minko
Summary: This study numerically simulates and experimentally verifies the presence of abnormal quasi-periodic high-amplitude temperature fluctuations in a liquid metal flow. These fluctuations are influenced by the physical properties of the channel walls and the electrical resistance between the fluid and the wall.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2024)
Article
Multidisciplinary Sciences
Jena Meinecke, Petros Tzeferacos, James S. Ross, Archie F. A. Bott, Scott Feister, Hye-Sook Park, Anthony R. Bell, Roger Blandford, Richard L. Berger, Robert Bingham, Alexis Casner, Laura E. Chen, John Foster, Dustin H. Froula, Clement Goyon, Daniel Kalantar, Michel Koenig, Brandon Lahmann, Chikang Li, Yingchao Lu, Charlotte A. J. Palmer, Richard D. Petrasso, Hannah Poole, Bruce Remington, Brian Reville, Adam Reyes, Alexandra Rigby, Dongsu Ryu, George Swadling, Alex Zylstra, Francesco Miniati, Subir Sarkar, Alexander A. Schekochihin, Donald Q. Lamb, Gianluca Gregori
Summary: Conventional theories on heat transport fail in magnetized, turbulent, weakly collisional plasmas, leading to a significant suppression of heat transfer. By replicating such a system in a laser laboratory experiment, we observe large temperature variations on small spatial scales.
Article
Mechanics
Shujaut H. Bader, Xiaojue Zhu
Summary: This study verifies the scaling law for the horizontal length scale in quasi-static magnetoconvection and derives scaling laws for the Nusselt number and the Reynolds number. The derived scaling relations are successfully validated using 2-D DNS data spanning a wide range of Q values.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Thermodynamics
A. Borrelli, G. Giantesio, M. C. Patria
Summary: This paper investigates the flow of a Bingham fluid in a vertical channel, considering the effects of an external magnetic field and natural convection. It is found that the velocity decreases with increasing Bingham and Hartmann numbers, and the presence of an external magnetic field increases the thickness of the plug region. The modulus of the induced magnetic field is not monotone with changes in the Hartmann number, but is a decreasing function of the Bingham number.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2022)
Article
Physics, Fluids & Plasmas
Jitender Singh
Summary: This numerical study investigates the parametric instability of a boussinesq fluid layer between two parallel planes, under the influence of time-periodic heating. The angle of inclination and temperature gradient across the layer determine the onset and nature of the instability. The modulation leads to convective-roll patterns and different spatial modes, with the angle of inclination being a function of the modulation. The temperature modulation offers great control over time-periodic heat and mass transfer.
Article
Mechanics
Shuiqing Zhan, Rui Yuan, Xiaohan Wang, Wei Zhang, Kai Yu, Bin Li, Zhentao Wang, Junfeng Wang
Summary: The growth and detachment dynamics of a single hydrogen bubble on microelectrode surfaces in water electrolysis were investigated using numerical simulation, force balance analysis, and experimental data. Multiple simulation cases with different bubble diameters were conducted to study the unsteady growth and detachment behavior. A force balance model was developed to predict bubble detachment diameter using simulated physical parameters and experimental results. The models were validated with previous experimental data and were found to accurately predict bubble detachment diameter.
Article
Mechanics
Jun Hu, Haoyang Wu, Baofang Song
Summary: Linear stabilities of liquid metal mixed convection in a horizontally heated pipe with a transverse magnetic field were studied. The study revealed different stability boundary curves for different Hartmann numbers and explained the destabilization mechanisms of different unstable modes through energy budget analyses.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Ivan Belyaev, Petr Sardov, Ivan Melnikov, Peter Frick
Summary: Experimental and numerical studies show that temperature gradients in channel flows of liquid metals induce strong buoyancy forces that result in specific magnetic field structures affecting magneto-convective fluctuations. The existence of MCFs in this system is determined by properties of the liquid metal, channel configuration, and governing flow parameters.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2021)
Article
Mechanics
Km Renu, Ashok Kumar, Abhishek K. Sharma
Summary: The study investigated the stably stratified flow in a linearly heated vertical pipe filled with a fluid-saturated porous medium, with a focus on the impact of permeability and Prandtl number on the stability of basic flow at different disturbance modes. The results demonstrate that the least stable mode depends on the values of Pr and Da, with a small range of Pr exhibiting a change in destabilizing characteristics to stabilizing characteristics for certain Da values.
Article
Mechanics
Alessio Boaro, Marcello Lappa
Summary: This study investigates the non-linear behavior of Marangoni convection by considering a differentially heated rectangular layer of liquid. The results show that with increasing values of the Marangoni number and/or elasticity parameter, there is a non-trivial interplay between transverse and longitudinal disturbances, leading to different outcomes. The characteristic marks of elastic turbulence are highlighted through analysis of the velocity spectrum scaling laws and their sensitivity to the driving force and elasticity level.
Article
Mechanics
Pengpeng Shi
Summary: This study focused on the direct numerical simulation of electroconvection to investigate the discrepancy between the thin Debye layer in simulations and canonical experiments, attributing the main cause to differences in the structural characteristics of the extended space charge layer. Matching the dimensionless thin Debye layer with canonical experiments enhances the driving force of the extended space charge layer, leading to the transition of electroconvective flow from steady state to time-dependent spatiotemporal dynamics. The thickness of the dimensionless thin Debye layer plays a key role in the high-precision quantitative analysis of electroconvection characteristics, providing important guidance for the design and instability control of microfluidic chips.
Article
Engineering, Petroleum
E. Lizarraga-Garcia, J. Buongiorno, E. Al-Safran
Summary: This study investigates the behavior of Taylor bubbles in vertical and inclined pipes with upward and downward flow using a validated 3D computational fluid dynamics (CFD) approach. A total of 56 cases were simulated, covering a wide range of fluid properties, pipe diameters, and inclination angles. The research found significant differences in the distribution parameter of bubbles between upward and downward or inclined slug flows.
Article
Mechanics
R. Akhmedagaev, O. Zikanov, D. Krasnov, J. Schumacher
JOURNAL OF FLUID MECHANICS
(2020)
Article
Mechanics
Ivan Belyaev, Dmitry Krasnov, Yuri Kolesnikov, Dmitry Biryukov, Denis Chernysh, Oleg Zikanov, Yaroslav Listratov
Review
Mechanics
Oleg Zikanov, Ivan Belyaev, Yaroslav Listratov, Peter Frick, Nikita Razuvanov, Valentin Sviridov
Summary: An imposed strong magnetic field can suppress turbulence and alter the flow of an electrically conducting fluid, such as in the case of mixed convection flows in pipes and ducts. This has implications for the design of liquid-metal components in future nuclear fusion reactors. The review outlines the recent studies on flow transformation, highlighting key facts and open questions in this area, as well as discussing implications for fusion reactor technology and novel methods.
APPLIED MECHANICS REVIEWS
(2021)
Article
Mechanics
Xuan Zhang, Robert E. Ecke, Olga Shishkina
Summary: In rapidly rotating turbulent Rayleigh-Benard convection with a small Prandtl number fluid in slender cylindrical containers, a boundary zonal flow (BZF) is found to develop near the sidewall, carrying a disproportionate amount of heat transport for Pr < 1 but decreasing abruptly for larger Pr. The BZF is robust and appears in containers of different aspect ratios and over a broad range of Pr and Ra values.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Thermodynamics
Linyan Xiang, Cheol W. Lee, Oleg Zikanov, Chih-Cheng Hsu
Summary: This paper introduces a method to overcome the high computational cost of CFD modeling by using reduced-order models to accurately predict the thermal behavior of thermal management systems for battery packs of electrical/hybrid electric vehicles. By using projection onto the Krylov subspace, algorithms for developing reduced-order models for both single-input and multiple-input cases are presented. The reduced-order models are validated through comparison with full-order CFD simulations, showing a reduction in computational time by approximately 10^3 without significant loss of accuracy.
APPLIED THERMAL ENGINEERING
(2022)
Article
Energy & Fuels
Chiara Mistrangelo, Leo Buehler, Ciro Alberghi, Serena Bassini, Luigi Candido, Cyril Courtessole, Alessandro Tassone, Fernando R. Urgorri, Oleg Zikanov
Summary: The European design strategy has identified mature concepts for DEMO breeding blankets that require reduced technological extrapolation and testing in ITER. Understanding magnetohydrodynamic interactions and other physical phenomena in liquid metal blankets is crucial for optimizing test blanket module designs. Both numerical and experimental approaches are being discussed to reliably predict processes in liquid metal blankets.
Article
Mechanics
Philipp Reiter, Xuan Zhang, Olga Shishkina
Summary: This work investigates the effects of different thermal sidewall boundary conditions on flow states and heat transport in Rayleigh-Benard convection. The study finds that different thermal conditions at the sidewall lead to significant differences in heat transport, but these differences become less pronounced for larger Rayleigh numbers.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
R. Akhmedagaev, O. Zikanov, Y. Listratov
Summary: The study investigates mixed convection in a horizontal duct with a horizontal magnetic field and constant-rate heating, finding that instability to quasi-two-dimensional rolls parallel to the magnetic field occurs in the previously unexplored range of control parameters for liquid metal blankets of nuclear fusion reactors. The transport of the rolls leads to exceptionally high amplitude magnetoconvective temperature fluctuations, and a quasi-two-dimensional flow structure at very high Hartmann numbers does not guarantee the accuracy of the classical two-dimensional approximation, deteriorating at the highest Grashof numbers considered in the study.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Fluids & Plasmas
Robert E. Ecke, Xuan Zhang, Olga Shishkina
Summary: Using direct numerical simulations, this study investigates rotating Rayleigh-Benard convection and connects linear wall-mode states with the boundary zonal flow in the geostrophic regime. The data from various sources are quantitatively collapsed, providing insights into the heat transport contributions of the wall modes and boundary zonal flow.
PHYSICAL REVIEW FLUIDS
(2022)
Article
Computer Science, Interdisciplinary Applications
Dmitry Krasnov, Ali Akhtari, Oleg Zikanov, Jorg Schumacher
Summary: A new approach combining conservative finite-difference discretization with a tensor-product-Thomas solution is proposed for numerical simulation of magnetohydrodynamic flows of liquid metals. The method efficiently solves the important elliptic problems for electric potential in flow domains with thin electrically conducting walls. Its effectiveness is demonstrated through benchmark problems and compared favorably to existing methods in terms of computational efficiency. (c) 2022 Elsevier Inc. All rights reserved.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Mechanics
Ivan A. A. Belyaev, Ivan S. S. Mironov, Nikita A. A. Luchinkin, Yaroslav I. I. Listratov, Yuri B. B. Kolesnikov, Dmitry Kransov, Oleg Zikanov, Sergei Molokov
Summary: This study experimentally investigates the dynamics of a liquid metal flow in the form of a submerged round jet entering a square duct in the presence of a transverse magnetic field. The results show that the instability of the jet leads to high-amplitude fluctuations, and the flow structure and fluctuation properties are determined by the value of the Stuart number.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Linyan Xiang, Cheol W. Lee, Oleg Zikanov, Mohamed Abuhegazy, Svetlana V. Poroseva
Summary: A new approach to numerical modeling of airborne transmission of respiratory infections in indoor environments is presented in this paper. The approach is based on the Eulerian description of the aerosol field and uses reduced-order modeling (ROM) to reduce computational cost. The ROM is validated through direct comparison with full-order computational fluid dynamics (CFD) solutions and Lagrangian tracking data. Computational tests show that the ROM reduces computational cost by a factor of about 10³ without significant loss in accuracy.
Article
Computer Science, Artificial Intelligence
Zhuo Wang, Wenhua Yang, Linyan Xiang, Xiao Wang, Yingjie Zhao, Yaohong Xiao, Pengwei Liu, Yucheng Liu, Mihaela Banu, Oleg Zikanov, Lei Chen
Summary: The article introduces a simple yet powerful multi-input convolutional network model called yNet, which can quickly simulate various field evolutions and accurately extrapolate predictions in terms of temporal ranges, spatial domains, and geometrical shapes.
Article
Physics, Multidisciplinary
D. Krasnov, Ya Listratov, Yu Kolesnikov, I Belyaev, N. Pyatnitskaya, E. Sviridov, O. Zikanov
Summary: In this study, the flow generated by a planar jet at the inlet of a duct and influenced by a perpendicular magnetic field was analyzed through high-resolution numerical simulations at very high Reynolds and Hartmann numbers. The flow structure in the inlet area was found to be significantly altered, with the emergence of three new planar jets along the magnetic field lines. The downstream evolution of the flow involves the Kelvin-Helmholtz instability of the jets and a slow decay of the resulting quasi-two-dimensional turbulence.
Article
Mechanics
I. A. Belyaev, N. Yu Pyatnitskaya, N. A. Luchinkin, D. Krasnov, Yu B. Kolesnikov, Ya Listratov, I. S. Mironov, O. Zikanov, E. Sviridov
Summary: This study experimentally investigates a liquid metal flat jet in a square duct under the influence of a transverse magnetic field, considering cases where the applied magnetic field is oriented parallel or perpendicular to the initial plane of the jet. By measuring signals of streamwise velocity at different locations, the study aims to determine average velocity profiles and spatial-temporal characteristics of the velocity field, comparing two configurations under the same flow regimes and equipment.
MAGNETOHYDRODYNAMICS
(2021)
