Article
Mechanics
Huanyu Zhang, Yakun Zhao, Xinliang Tian, Xiaolong Wang, Hao Liu
Summary: This paper investigates the motion modes transition and dynamic performance of a rigid-flexible coupling system in the flow at low Reynolds numbers. The system consists of a rigid plate and a trailing closed flexible filament, and numerical simulations using the immersed boundary method are conducted. Six motion modes are identified based on the movement of the filament and its symmetry. Drag reduction is observed at Re >= 40, mainly influenced by the pressure behind the filament. However, the drag reduction is weakened for filaments with Lr >= 2.57 due to the increased flow disturbance caused by their large width.
Article
Mechanics
Yin Guan, Shuang Wu, Mengduo Wang, Yu Tian, Chuanpeng Yu, Wuxing Lai, YongAn Huang
Summary: This study numerically investigates the mechanism of high-frequency pulsating electrohydrodynamic jet at low electric Bond numbers. By analyzing parameters such as voltage distribution, electric charge density, and flow field, the influences of factors like electric voltage, nozzle-to-substrate distance, and liquid surface tension coefficient on the dynamic behaviors and durations of three jetting stages are revealed. Additionally, the relative significance of electric force to surface tension force and the impacts of electric Bond number on the jetting process are also examined.
Article
Engineering, Marine
Amina Sabeur, Houda Soufi
Summary: This research conducts a numerical investigation of the flow around a two-dimensional circular cylinder under the influence of combined unidirectional and oscillating flow. The results show that a steady current has a significant impact on forces acting on the cylinder and the vorticity fields. The transition from a stationary cylinder's fluid oscillation to an oscillation in uniform flow can be prolonged for certain current ratio numbers, and a lock-on state can be achieved at moderate values of the current ratio number.
Article
Mechanics
B. Magacho, H. S. Tavares, L. Moriconi, J. B. R. Loureiro
Summary: We have developed an improved lattice-Boltzmann numerical scheme based on the CM and MRT collision models to solve MHD equations at low magnetic Reynolds numbers. We have introduced a MRT technique to solve the magnetic induction equation and a novel boundary condition method to handle Boltzmann-like distributions on curved boundaries. The proposed CM-MRT algorithm has been applied to simulate the dynamics of the Orszag-Tang vortex problem and transient flow regimes in MHD pipe flows with uniform and non-uniform magnetic fields.
Article
Mechanics
Jinhao Zhang, Lijuan Shi, Zhanqi Tang, Xingyu Ma, Nan Jiang
Summary: In this study, the two-dimensional flow characteristics caused by hemisphere disturbance in the laminar boundary layer were experimentally investigated. The periodic vortex structures generated at different freestream velocities were analyzed. The results showed strong shear in the dense area of velocity contours, including stable horizontal shear layers and inclined shear layers of shedding vortex structures. The feasibility of three frequency extraction methods for hemisphere disturbance was compared, and the periodic structures corresponding to each frequency were analyzed. The study also found that the periodic vortex structures transformed from a single frequency state to a multi-frequency superposition state with an increase in Reynolds number. Overall, this research provides valuable insights into the flow characteristics and vortex structure formation mechanisms in the laminar boundary layer.
Article
Engineering, Chemical
Shaowei Wang, Huanpeng Liu
Summary: The study found that the Reynolds number and fractal dimension of agglomerates significantly affect the flow field, and drag ratios obtained from numerical simulation agree well with experimental data. The effect of radial variation of permeability on drag force seems almost negligible in the range of moderate Reynolds numbers.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2021)
Article
Mechanics
Michele Cogo, Francesco Salvadore, Francesco Picano, Matteo Bernardini
Summary: The structure of high-speed zero-pressure-gradient turbulent boundary layers was studied using direct numerical simulation of the Navier-Stokes equations up to high Reynolds numbers, revealing the consequences in supersonic and hypersonic conditions. Instantaneous fields showed elongated strips of uniform velocity and temperature with clear associations between different streaks.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Renfang Huang, Rundi Qiu, Yuchang Zhi, Yiwei Wang
Summary: This study investigates the behaviors of ventilated cavities around a surface-piercing hydrofoil at high Froude numbers. Through experiments and modeling analysis, the study reveals the characteristics of vaporous cavitating flow and explores the transition from fully wetted flow to fully ventilated flow. The findings lay a foundation for the design optimization and control strategy of high-speed hydrofoils.
Article
Engineering, Marine
Abel Arredondo-Galeana, Aristides Kiprakis, Ignazio Maria Viola
Summary: This paper investigates the active surface morphing technique at low cost and low Reynolds number for underwater applications. Experimental results show that the method can increase lift by 1% and decrease drag by 6% under fast actuation. The approach is applicable to the marine environment and more economical than existing technologies.
JOURNAL OF MARINE SCIENCE AND ENGINEERING
(2022)
Article
Mechanics
Qingrui Meng, Hongwei An, Liang Cheng, Mehrdad Kimiaei
Summary: Numerical investigation on wake transitions behind an isolated cube revealed four different flow regimes and their evolution patterns. The study also identified the transition mechanisms between vortex shedding states and the critical Reynolds numbers for bifurcations to different regimes.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Engineering, Mechanical
B. Koncar, J. Sotosek, I. Bajsic
Summary: This study presents experimental verification and numerical simulations of a vortex flow meter in a wide range of Reynolds numbers. The results show a clear linear relationship between the shedding frequency and the volumetric flow rate. The numerical simulations also help to understand the main mechanisms of vortex formation and shedding.
FLOW MEASUREMENT AND INSTRUMENTATION
(2022)
Article
Engineering, Chemical
Zahra Sayyar, Javad Rahbar Shahrouzi, Ali Akbar Babaluo
Summary: A self-cleaning Fe/TiO2 surface coating was prepared on a ceramic substrate using the cold spray method based on sol-gel and hydrothermal processes. The effect of spraying operation conditions on the coated layer thickness was investigated using a numerical method. The results showed that the pressure, traverse speed, and standoff distance influenced the thickness of the coating. The proposed optimum condition exhibited good performance in photocatalytic and antibacterial tests.
Article
Engineering, Civil
Pu Li, Kuandi Zhang, Jingwen Wang, He Meng, Alessio Nicosia, Vito Ferro
Summary: This paper examines overland flow resistance at low Reynolds numbers through experimental runs. The analysis reveals that the power relationship between the Darcy-Weisbach friction factor and Reynolds number applies to water only flows, with a threshold value of 500 for transition to turbulent flow. The calibrated theoretical relationship allows accurate estimation of flow resistance for mixed fluid flows as well, even at Reynolds numbers below 7.
JOURNAL OF HYDROLOGY
(2022)
Article
Mechanics
Lingxin Zhang, Kai Peng, Xueming Shao, Jian Deng
Summary: This study numerically investigates the dynamics of gas bubbles rising freely under buoyancy at low Reynolds numbers, focusing on clustering morphology and velocity fluctuations' probability density functions. The research reveals that the probability density functions for bubble velocity fluctuations exhibit distinct behavior at high gas fractions compared to high Reynolds number experiments, indicating that strong bubble-bubble interactions trigger turbulent flow efficiently.
Article
Computer Science, Interdisciplinary Applications
N. Roy, R. Duerr, A. Bueck, J. Kumar, S. Sundar
Summary: This paper rigorously investigates three numerical methods for solving the population balance equation coupled with hydrodynamics, analyzing their advantages and disadvantages in various test cases. It recommends the WFVS as a smart choice for computing number density and moments in the case of inhomogeneous PBE.
MATHEMATICS AND COMPUTERS IN SIMULATION
(2022)
Article
Computer Science, Interdisciplinary Applications
Jin Bao, Zhaoli Guo
Summary: At the equilibrium state of a two-phase fluid system, the chemical potential is constant and the velocity is zero. However, it is challenging to capture this equilibrium state accurately in numerical simulations, resulting in inconsistent thermodynamic interfacial properties and spurious velocities. Therefore, numerical schemes with well-balanced properties are preferred for simulating two-phase flows.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Brian C. Vermeire
Summary: This study presents a framework for implicit large eddy simulation (ILES) of incompressible flows by combining the entropically damped artificial compressibility (EDAC) method with the flux reconstruction (FR) approach. Experimental results demonstrate that the method is accurate and stable for low-order solutions, while higher-order solutions exhibit significantly higher accuracy and lower divergence error compared to reference direct numerical simulation.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Mijian Li, Rui Wang, Xinyu Guo, Xinyu Liu, Lianzhou Wang
Summary: In this study, the flow mechanisms around wall-mounted structures were investigated using Large Eddy Simulation (LES). The impact of inflow turbulence on the flow physics, dynamic response, and hydrodynamic performance was explored. The results revealed strong interference between velocity fluctuations and the wake past the cylinder, as well as significant convection effects in the far wake region.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Donatella Passiatore, Luca Sciacovelli, Paola Cinnella, Giuseppe Pascazio
Summary: A high-order shock-capturing central finite-difference scheme is evaluated for numerical simulations of hyper-sonic high-enthalpy flows out of thermochemical equilibrium. The scheme utilizes a tenth-order accurate central-difference approximation of inviscid fluxes, along with high-order artificial dissipation and shock-capturing terms. The proposed approach demonstrates accuracy and robustness for a variety of thermochemical non-equilibrium configurations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Philipp Bahavar, Claus Wagner
Summary: Condensation is an important aspect in flow applications, and simulating the gas phase and tracking the deposition rates of condensate droplets can capture the effects of surface droplets on the flow while reducing computational costs.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Andras Szabo, Gyorgy Paal
Summary: This paper introduces an efficient calculation method, the parabolized stability equations (PSE), for solving stability equations. By calculating LU factorization once in each marching step, the time spent on solving linear systems of equations can be significantly reduced. Numerical experiments demonstrate the effectiveness of this method in reducing the solution time for linear equations, and its applicability to similar problems.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
A. Khalifa, M. Breuer
Summary: This study evaluates a recently developed data-driven model for collision-induced agglomerate breakup in high mass loading flows. The model uses artificial neural networks to predict the post-collision behavior of agglomerates, reducing computational costs compared to coupled CFD-DEM simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Chunmei Du, Maojun Li
Summary: This paper considers the bilayer shallow water wave equations in one-dimensional space and presents an invariant domain preserving DG method to avoid Kelvin-Helmholtz instability.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jean-Michel Tucny, Mihir Durve, Andrea Montessori, Sauro Succi
Summary: The prediction of non-equilibrium transport phenomena in disordered media is a challenging problem for conventional numerical methods. Physics-informed neural networks (PINNs) show potential for solving this inverse problem. In this study, PINNs were used to successfully predict the velocity field of rarefied gas flow, and AdamW was found to be the best optimizer.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Min Gao, Pascal Mossier, Claus-Dieter Munz
Summary: In recent decades, the arbitrary Lagrangian-Eulerian (ALE) approach has gained popularity in dealing with fluid flows with moving boundaries. This paper presents a novel algorithm that combines the ALE finite volume (FV) and ALE discontinuous Galerkin (DG) methods into a stable and efficient hybrid approach. The main challenge of this mixed ALE FV and ALE DG method is reducing the inconsistency between the two discretizations. The proposed algorithm is implemented into a loosely-coupled fluid-structure interaction (FSI) framework and is demonstrated through various benchmark test cases and complex scenarios.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Dawid Strzelczyk, Maciej Matyka
Summary: In this study, the numerical convergence of the Meshless Lattice Boltzmann Method (MLBM) is investigated through three benchmark tests. The results are compared to the standard Lattice Boltzmann Method (LBM) and the analytical solution of the Navier-Stokes equation. It is found that MLBM outperforms LBM in terms of error value for the same number of nodes discretizing the domain.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Kanishka Bhattacharya, Tapan Jana, Amit Shaw, L. S. Ramachandra, Vishal Mehra
Summary: In this work, an adaptive algorithm is developed to address the issue of tensile instability in Smoothed Particle Hydrodynamics (SPH) by adjusting the shape of the kernel function to satisfy stability conditions. The effectiveness of the algorithm is demonstrated through dispersion analysis and fluid dynamics simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Luis Laguarda, Stefan Hickel
Summary: We propose several enhancements to improve the accuracy and performance of the digital filter turbulent inflow generation technique, such as introducing a more realistic correlation function and varying target length scales. Additionally, we suggest generating inflow data in parallel at a prescribed time interval to improve computational performance. Based on the results of large-eddy simulations, these enhancements have shown to be beneficial. Suppressing streamwise velocity fluctuations at the inflow leads to the fastest relaxation of pressure fluctuations. However, this approach increases the adaptation length, which can be shortened by artificially increasing the wall-normal Reynolds stresses.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Constantin Zenz, Michele Buttazzoni, Tobias Florian, Katherine Elizabeth Crespo Armijos, Rodrigo Gomez Vazquez, Gerhard Liedl, Andreas Otto
Summary: A new model for compressible multiphase flows involving sharp interfaces and phase change is presented, with a focus on the treatment of compressibility and phase change in the multiphase fluid flow model. The model's accuracy and suitability are demonstrated through comparisons with experimental observations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Joseph O'Connor, Sylvain Laizet, Andrew Wynn, Wouter Edeling, Peter V. Coveney
Summary: This article aims to apply uncertainty quantification and sensitivity analysis to the direct numerical simulation (DNS) of low Reynolds number wall-bounded turbulent channel flow. By using a highly scalable DNS framework and UQ techniques, the study evaluates the influence of different numerical parameters on the simulation results without explicitly modifying the code. The findings provide guidance for numerical simulations of wall-bounded turbulent flows.
COMPUTERS & FLUIDS
(2024)