Article
Physics, Multidisciplinary
Zhong-Hong Xi, Yong-Zhen Zhao, Yu-Ren Shi
Summary: This study investigates the Benard-von Karman vortex street in dipolar Bose-Einstein Condensate trapped by a harmonic potential using numerical simulations. It is found that under specific conditions, vortex pairs released from a moving obstacle potential in dipolar BEC can form a Benard-von Karman vortex street. The research also examines the effects of dipole interaction strength, obstacle potential width, and velocity on the vortex structure produced in the wake, and calculates the drag force on the obstacles potential.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2021)
Article
Multidisciplinary Sciences
Jurgen Schmiegel, Flavio Pons
Summary: The study explores the application of stochastic intermittency fields in analyzing the statistical properties of turbulence intensity time series in anisotropic and inhomogeneous turbulent flows, providing concise one-, two-, and three-point statistics descriptions. It is found that three-point correlations can be predicted from observed two-point statistics and the similarity in energy dissipation features in homogeneous and isotropic situations suggests that stochastic intermittency fields may have relevance in broader contexts.
Article
Engineering, Chemical
Fan Xu, Peng Zhao, Chao Sun, Yurong He, Junwu Wang
Summary: In this study, the effect of axial walls on the hydrodynamics of Taylor-Couette reactors (TCR) was investigated using direct numerical simulation (DNS). The results showed that the impact of axial walls on the torque is regime-dependent, with a significant effect observed in the laminar Taylor vortices regime. The maximal effect occurs near the critical Ta for the onset of laminar Taylor vortices, with a relative deviation of torques up to 15:1% between axial PBC and walls. Additionally, the aspect ratio of TCR also influences the torque, with a smaller effect observed in reactors with larger aspect ratios.
CHEMICAL ENGINEERING SCIENCE
(2022)
Article
Engineering, Multidisciplinary
Hongwei Guo, Xitailang Cao, Zenglong Liang, Shan Lin, Hong Zheng, Hao Cui
Summary: This paper presents the Hermitian manifold numerical method (HNMM) for the finite strain analysis of thin plates with irregular domains. The large deflection of elastic thin plates is described by the Foppl-von Karman (FvK) equations and nonlinear fourth-order partial differential equations. The HNMM can construct an approximation to solutions that satisfy the H-2 regularity requirements with structured meshes, and it can also embed classical plate elements in the framework to solve plates with irregular domains. The numerical results demonstrate the accuracy of HNMM in analyzing the large deflection of Foppl-von Karman plates with complex domain shapes.
ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
(2023)
Article
Multidisciplinary Sciences
Kuan Li, J. B. Marston, Steven M. Tobias
Summary: This paper investigates the effectiveness of direct statistical simulation (DSS) for two low-order models of dynamo action. It compares two different techniques for solving for the statistics of these models and demonstrates the development of a complete methodology and symbolic package in Python for deriving the statistical equations. It concludes that while direct detection of fixed points is efficient and accurate for DSS truncated at second order, timestepping is more robust for finding meaningful solutions when higher order terms are included.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Mathematics, Applied
R. H. W. Hoppe
Summary: This paper presents a space-time adaptive C-0 Interior Penalty Discontinuous Galerkin (C(0)IPDG) approximation method for the dynamic quasi-static von Karman equations, including homogeneous Dirichlet boundary conditions and an equilibrated a posteriori error estimator. The backward Euler scheme is used for time discretization, and the C(0)IPDG method is derived from a six-field formulation of the finite element discretized von Karman equations. The equilibrated a posteriori error estimator provides an upper bound for the discretization error in terms of associated energy functionals. It requires the construction of equilibrated fluxes and moment tensors computed on local patches around interior nodal points.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Thermodynamics
Xiaosheng Liu, Dong Hou, Jun Ji, Hui Zhu
Summary: This paper investigates the impact of fire detector sensitivity on fire detection results through experiments and numerical simulations. The results demonstrate that detectors with lower alarm thresholds have shorter response times, and the sensitivity of suction-type smoke detectors significantly affects detection outcomes.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Engineering, Marine
Xiang Xia, Liangcheng Ge, Lingjiu Zhou, Yingyao Feng, Haiyan Zeng, Zhengwei Wang
Summary: The Karman vortex street is a common phenomenon in fluid dynamics, and the asymmetry of flow velocity has a significant impact on the strength of the wake vortex. Numerical simulations showed that the shedding frequency and intensity of the vortex change with the increase of velocity asymmetry.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Chemistry, Physical
Marek Kowalik, Piotr Paszta, Tomasz Trzepiecinski, Leon Kukielka
Summary: The article introduces an original technology for controlling the curvature of hollow curved pipes during extrusion. By designing the die and optimizing the extrusion process, precise control of the radius of curvature can be achieved.
Article
Nuclear Science & Technology
David Reger, Elia Merzari, Paolo Balestra, Sebastian Schunert, Yassin Hassan, Stephen King
Summary: An understanding of the flow physics in packed beds is essential for pebble bed reactors. Computational fluid dynamics simulations using the NekRS code successfully predict velocity and pressure drop in two different cases, and agreement is found between experiments and simulations. Turbulent kinetic energy production analysis reveals negative production near the bottom surfaces of the pebbles, suggesting the influence of inertial effects on flow differentiation in packed beds.
NUCLEAR TECHNOLOGY
(2023)
Article
Mechanics
Jiasheng Yang, Alexander Stroh, Daniel Chung, Pourya Forooghi
Summary: Direct numerical simulations (DNS) are used to predict the accuracy of roughness function and zero-plane displacement in properly sized minimal channels. The predictions remain accurate even when the domain size is reduced and 90% of the roughness height variance is retained. The roughness function is nearly unique for deterministic different surface topographies. The distribution of surface force exerted by the roughness can be well captured when considering the sheltering effect.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Mateus C. Guimaraes, Fernando T. Pinho, Carlos B. da Silva
Summary: This study employs the FENE-P model to conduct direct numerical simulations and investigate the far-field region of turbulent wakes of viscoelastic fluids. The results show new scaling laws for various parameters and are well supported by the numerical simulations. When the Weissenberg and Deborah numbers are sufficiently large, turbulent viscoelastic wakes exhibit distinctive behavior compared to Newtonian wakes.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Thermodynamics
Xin Xiang, Jingde Zhu, Xiaoan Hu, Chen Xia, Hongyi Lu
Summary: This paper conducted a numerical study on the migration characteristics of hot streaks in a micro axial turbine, revealing differences in heat deposition and migration phenomena compared to conventional turbines. The results provide theoretical reference for the aerodynamic and cooling design of micro axial turbines.
CASE STUDIES IN THERMAL ENGINEERING
(2021)
Article
Mathematics
Jozef Melcer, Eva Merciakova, Maria Kudelcikova, Veronika Valaskova
Summary: This article focuses on the numerical simulation and experimental verification of a vehicle's response to kinematic excitation caused by driving on an asphalt road. The study involved mapping road unevenness, developing a computational model, deriving equations of motion, and comparing experimentally obtained and numerically simulated results.
Article
Mechanics
Jiarong Wu, Stephane Popinet, Luc Deike
Summary: This study investigates wind wave growth through direct numerical simulations solving the two-phase Navier-Stokes equations. The research finds that pressure forcing plays a leading role in finite amplitude gravity waves and wave form drag force is closely related to wave steepness rather than wave age. By offering new direct evidence, potential wind wave growth theories are supported.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
W. Herreman, C. Nore, P. Ziebell Ramos, L. Cappanera, J-L Guermond, N. Weber
PHYSICAL REVIEW FLUIDS
(2019)
Article
Mathematics, Applied
Daniel Castanon Quiroz, Daniele A. Di Pietro
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2020)
Article
Physics, Fluids & Plasmas
W. Herreman, S. Benard, C. Nore, P. Personnettaz, L. Cappanera, J. -L. Guermond
PHYSICAL REVIEW FLUIDS
(2020)
Article
Computer Science, Interdisciplinary Applications
L. Cappanera, P. Debue, H. Faller, D. Kuzzay, E-W Saw, C. Nore, J-L Guermond, F. Daviaud, C. Wiertel-Gasquet, B. Dubrulle
Summary: This paper investigates the comparison between experimental, direct numerical simulation (DNS), and large eddy simulation (LES) results in a von Karman flow, where two counter-rotating impellers are driving the fluid in a cylindrical container. The study validates the proposed LES model and demonstrates a high level of agreement between numerical and experimental data, indicating that each technique can be used with high confidence to explore and understand turbulence in complex flows at Reynolds numbers of O(10^5) and beyond.
COMPUTERS & FLUIDS
(2021)
Article
Mathematics, Applied
Vivette Girault, Beatrice Riviere, Loic Cappanera
Summary: This paper introduces a convergence analysis of a finite element method with mass-lumping and flux upwinding for solving the immiscible two-phase flow problem in porous media. The numerical results demonstrate strong convergence of phase saturation and pressure in space, which is essential for addressing complex models.
JOURNAL OF NUMERICAL MATHEMATICS
(2021)
Article
Mathematics, Applied
Vivette Girault, Beatrice Riviere, Loic Cappanera
Summary: A finite element method with mass-lumping and flux upwinding is used to solve the immiscible two-phase flow problem in porous media. The method approximates the wetting phase pressure and saturation directly, and the discrete saturation satisfies a maximum principle. The stability of the scheme and existence of a solution are established.
JOURNAL OF NUMERICAL MATHEMATICS
(2021)
Article
Mechanics
W. Herreman, C. Nore, L. Cappanera, J-L Guermond
Summary: This study demonstrates that swirling electrovortex flows can significantly enhance the mixing of alloys in the bottom layer of liquid metal batteries during discharge. By identifying a novel scaling law for the intensity of these flows and using a model developed in a previous study, the minimal intensity of the external magnetic field required for this enhancement is estimated.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
H. Faller, D. Geneste, T. Chaabo, A. Cheminet, V. Valori, Y. Ostovan, L. Cappanera, Ch. Cuvier, F. Daviaud, J. -M. Foucaut, J. -L. Guermond, J. -Ph. Laval, C. Nore, V. Padilla, C. Wiertel, B. Dubrulle
Summary: Through numerical and experimental data, the study finds that the structure functions of small scale turbulence exhibit a generalized extended scaling and have consistent multi-fractal spectra, supporting a local refined hypothesis. Both areas of strong vorticity and strong local energy transfer show high intermittency and correlation. In the shear layer, there is a stronger correlation between vorticity and local energy transfer, possibly indicating a self-similar quasi-singular structure dominating the scaling properties of large order structure functions.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
C. Nore, L. Cappanera, J-L Guermond, T. Weier, W. Herreman
Summary: By combining theoretical arguments and numerical simulations, we have shown that metal pad roll instability can occur in a centimeter-scale setup with reasonable values of magnetic field and electrical current, using metal pairs that are liquid at room temperature. We have investigated two fluid pairs: gallium with mercury (immiscible pair) or gallium with GaInSn eutectic alloy (miscible pair).
PHYSICAL REVIEW LETTERS
(2021)
Article
Mathematics, Applied
Michele Botti, Daniel Castanon Quiroz, Daniele A. Di Pietro, Andre Harnist
Summary: This paper introduces and analyzes a Hybrid High-Order discretization method for the steady motion of non-Newtonian, incompressible fluids in the Stokes approximation. The method supports general meshes, has unconditional inf-sup stability, and achieves orders of convergence matching those obtained for scalar Leray-Lions problems. Well-posedness and convergence analysis of the method is carried out under new, general assumptions on the strain rate-shear stress law, covering common models like the power-law and Carreau-Yasuda models. Numerical examples are provided for illustration.
ESAIM-MATHEMATICAL MODELLING AND NUMERICAL ANALYSIS-MODELISATION MATHEMATIQUE ET ANALYSE NUMERIQUE
(2021)
Article
Mathematics, Applied
Gabriela Jaramillo, Loic Cappanera, Cory Ward
Summary: In this paper, a numerical scheme based on quadratures is developed to approximate solutions of integro-differential equations involving convolution kernels. Convergence of the scheme is shown for different conditions, including bounded domains and nonlocal boundary conditions. The results also apply to the Neumann problem due to equivalent formulations with nonlocal Neumann boundary conditions.
JOURNAL OF SCIENTIFIC COMPUTING
(2021)
Article
Mathematics, Applied
Daniel Castanon Quiroz, Daniele A. Di Pietro, Andre Harnist
Summary: In this work, a Hybrid High-Order (HHO) discretization method for incompressible flows of non-Newtonian fluids with power-like convective behaviour is designed and analyzed. The existence and uniqueness of a solution are determined by the interplay of certain exponents. A stable and convergent HHO scheme is developed based on a weak formulation, and its effectiveness is validated on various model problems.
IMA JOURNAL OF NUMERICAL ANALYSIS
(2023)
Article
Mathematics, Applied
Giselle Sosa Jones, Loic Cappanera, Beatrice Riviere
Summary: This paper presents and analyzes a discontinuous Galerkin method for the incompressible three-phase flow problem in porous media. The algorithm is validated through theoretical analysis and numerical results, demonstrating a first-order convergence.
IMA JOURNAL OF NUMERICAL ANALYSIS
(2023)
Article
Mathematics, Applied
Daniel Castanon Quiroz, Daniele A. Di Pietro
Summary: In this paper, a pressure-robust hybrid high-order method is introduced for the numerical solution of the incompressible Navier-Stokes equations on matching simplicial meshes. A novel divergence-preserving velocity reconstruction is proposed, and discretizations of the body force and convective terms are designed to achieve pressure robustness.
IMA JOURNAL OF NUMERICAL ANALYSIS
(2023)
Article
Mechanics
W. Herreman, L. Wierzchalek, G. M. Horstmann, L. Cappanera, C. Nore
Summary: In this study, the metal pad roll instability in liquid metal batteries is investigated. The growth rates of gravity waves near the instability threshold are calculated using perturbation methods. The results are in good agreement with previous and new numerical simulations. The theory can also be used to estimate a lower bound on cell size for the occurrence of metal pad roll instability.
JOURNAL OF FLUID MECHANICS
(2023)
