Article
Mathematics
Oleg Ilyin
Summary: In the entropic lattice Boltzmann approach, the parameter alpha governs the stability properties and viscosity of a flow. This study addresses the problem of evaluating alpha to secure the fulfillment of the discrete H-theorem with an average value close to alpha = 2. The proposed method approximates the H-function by a quadratic function and derives an analytical expression for alpha based on the entropy balance requirement. Simulation results validate the formula by demonstrating very small excessive dissipation.
Article
Chemistry, Physical
Ivan Pribec, Anze Hubman, Tomaz Urbic, Igor Plazl
Summary: The lattice Boltzmann method (LBM) is a computational method used for a wide range of fluid flow and multiphysics phenomena, where reactions can be incorporated through reactive source terms or particle distribution functions in order to simulate velocity-dependent reactive collisions of particles.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Multidisciplinary
Jia Xu, TieZhu Qiao, Qing Li, GuoWei Zhang, GuiRong Hao
Summary: This study proposes an optimization method of crystal rotation to improve the quality of crystal seeding under complex convection. By calculating and analyzing the unsteady melt flow rate, internal temperature of the melt, and crystal rotation speed, the results show that this method can effectively restrain melt convection and improve the temperature distribution on the surface of the melt.
Article
Mathematics, Applied
Xiang An, Bo Dong, Weizhong Li, Xun Zhou, Tao Sun
Summary: In this paper, a new lattice Boltzmann model is proposed to investigate binary droplet collisions. Through simulating collision features at different collision angles, it is found that the percentage of satellite droplet is highest at 60 degrees, while lower at 90 degrees, 120 degrees, and 150 degrees.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2021)
Article
Mechanics
Geng Wang, Linlin Fei, Kai H. Luo
Summary: The study uses a lattice Boltzmann model to simulate the dynamics of water droplets penetrating a micropillar array in a microchannel, validating the model through experiments and conducting a parametric study. It finds that the fingering dynamics of the droplet in the longitudinal direction is governed by the competition between dynamic and capillary pressures, while permeation in the lateral and vertical directions is dominated by the capillary effect. Changing the droplet initial velocity and configuration setup significantly influences the droplet penetration velocity, maximum wetted surface area, and penetration rate.
Article
Mechanics
Qiao-Zhong Li, Zhi-Liang Lu, Di Zhou, Xiao-Dong Niu, Tong-Qing Guo, Bing-Chen Du, You Li
Summary: This work presents a comprehensive numerical study of the magnetic field-induced dynamic self-assembly process of multiple bubbles inside a ferrofluid. Factors such as magnetic field strength, surface tension coefficient, and initial position play important roles in influencing the efficiency of the self-assembly process.
Article
Chemistry, Multidisciplinary
Bifeng Yin, Sheng Xu, Shuangyu Yang, Fei Dong
Summary: The study found that the microhole surface can achieve a superhydrophobic state, with the contact angle rapidly decreasing when the diameter is too large. As the microhole diameter increases, the relative radii of the x- and y-directions show an increasing trend, while an increasing spacing leads to a decreasing trend in the relative radii of x- and y-directions.
Article
Physics, Fluids & Plasmas
Hong Liang, Runlong Wang, Yikun Wei, Jiangrong Xu
Summary: In this paper, an accurate interface-capturing lattice Boltzmann method is proposed based on the modified Allen-Cahn equation for modeling an immiscible multiphase flow system. The proposed method is built on the relation between the signed-distance function and the order parameter, maintaining the mass-conserved characteristic. By carefully incorporating a suitable forcing term, the target equation can be correctly recovered. Simulation results for various interface-tracking problems demonstrate that the proposed model is more numerically accurate, particularly at a small interface-thickness scale, compared to existing lattice Boltzmann models for the conservative Allen-Cahn equation.
Article
Mechanics
Yi Zhou, Zhengdao Wang, Yuehong Qian, Hui Yang, Yikun Wei
Summary: This study presents a numerical investigation on flow around two square cylinders in different arrangements, revealing various flow patterns that can be categorized into three types depending on the spacing between the cylinders. The dependence of flow parameters on spacing is demonstrated, and the relationship between flow pattern and lift and drag coefficients is explored.
Article
Physics, Fluids & Plasmas
Ruofan Qiu, Tao Zhou, Yue Bao, Kang Zhou, Huanhuan Che, Yancheng You
Summary: This paper presents a mesoscopic kinetic approach based on molecular velocity distribution to better understand nonequilibrium hydrodynamic and thermodynamic effects in shock waves, contact discontinuities, and rarefaction waves. The study focuses on the one-dimensional unsteady shock tube problem to probe the mechanism of nonequilibrium effect in discontinuous flows, using lattice Boltzmann method to solve the flow field and describing nonequilibrium effects through kinetic moments of molecular velocity distribution functions.
Article
Thermodynamics
Sirui Lu, Hao Lu, Lina Hu, Xiaojian Wang
Summary: This study investigated the bouncing process of droplets on superhydrophobic surfaces using the lattice Boltzmann method. Different micro-structures of superhydrophobic surfaces were compared and summarized in terms of the droplet bouncing characteristics. The study revealed that the maximum spreading length of the droplet decreases with increasing surface irregularities, and the contact time and post-bounce morphology were analyzed. The study also presented a new law of droplet bouncing from progressively more complex surface microstructures.
CASE STUDIES IN THERMAL ENGINEERING
(2023)
Article
Mechanics
Qin Xu, Zijian Zhuang, Yongcai Pan, Binghai Wen
Summary: In this paper, a super-resolution transformer is proposed to reconstruct turbulent flow fields with high quality. Through experiments on forced isotropic turbulence and turbulent channel flow datasets, the results show that the proposed method can recover the turbulent flow fields with high spatial resolution and capture small-scale details. It can also handle both isotropic and anisotropic turbulent properties even in complex flow configurations.
Article
Mechanics
Zeren Yang, Sha Liu, Congshan Zhuo, Chengwen Zhong
Summary: The novel MDUGKS is proposed for modeling multiphase flows with large density ratios, overcoming stability issues encountered by standard DUGKS on multilevel meshes. Numerical solutions are in good agreement with theoretical predictions, demonstrating high efficiency and accuracy in steady and unsteady cases.
Article
Mechanics
Zhenyu Ouyang, Jianzhong Lin
Summary: The hydrodynamic behavior of a two-dimensional elongated micro-swimmer in a bulk fluid was studied using numerical methods. The study found that the swimming speed and power expenditure of different types of swimmers varied depending on their structures and the flow conditions.
Article
Mechanics
Rongzong Huang
Summary: We present a macroscopic dynamic van der Waals theory for liquid-vapor phase transition from mesoscopic perspectives offered by the kinetic model for multiphase fluids. The present dynamic equations are identical to the macroscopic equations recovered by the kinetic model, revealing the excess effects caused by unbalanced long-range molecular interaction in the inhomogeneous region.
Article
Physics, Multidisciplinary
Nicolo Frapolli, Shyam Chikatamarla, Ilya Karlin
Article
Mechanics
N. Sawant, B. Dorschner, I. V. Karlin
Summary: A new lattice Boltzmann model for multicomponent ideal gas mixtures is proposed, which consists of two parts for modeling the dynamics and energy of the mixture. The model eliminates passive scalar advection-diffusion coupling and extends the lattice Boltzmann equation to the compressible flow regime on the standard three-dimensional lattice.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Physics, Multidisciplinary
Mohammad Hossein Saadat, Benedikt Dorschner, Ilya Karlin
Summary: The translation describes a method of modifying conventional lattice Boltzmann models to remain effective at higher flow velocities and temperatures, and validates this approach through simulations of benchmark problems in two and three dimensions.
Article
Mechanics
M. H. Saadat, S. A. Hosseini, B. Dorschner, I. V. Karlin
Summary: The two-population lattice Boltzmann model proposed in this study accurately simulates compressible flows, demonstrating good performance even in the presence of turbulence and shock waves.
Article
Multidisciplinary Sciences
N. Sawant, B. Dorschner, I. Karlin
Summary: A new lattice Boltzmann model for reactive ideal gas mixtures is proposed, which improves the kinetic model for Stefan-Maxwell diffusion and enhances thermodynamic consistency by incorporating the heat of formation to accurately describe the energy and temperature changes due to chemical reactions. The model is validated with benchmarks including laminar burning speed in hydrogen-air mixture and circular expanding premixed flame, demonstrating its effectiveness for reactive flows.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2021)
Article
Mechanics
Abhimanyu Bhadauria, Benedikt Dorschner, Ilya Karlin
Summary: This paper introduces a two-way coupled fluid-structure interaction scheme for rigid bodies using a two-population lattice Boltzmann formulation for compressible flows. The model, validated with several test cases, accurately captures dynamic behavior of systems, especially in the compressible flow regime. It demonstrates the ability to accurately describe complex phenomena, such as transonic flutter over an airfoil.
Article
Mechanics
N. Sawant, B. Dorschner, I. Karlin
Summary: A new lattice Boltzmann model (LBM) is proposed for chemically reactive mixtures, which extends the non-reactive LBM to include diffusion and flow modeling for chemical species and compressible flow. The model is validated against direct numerical simulation and shows excellent accuracy and applicability for complex reactive flows.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
S. A. Hosseini, B. Dorschner, I. V. Karlin
Summary: This paper revisits the construction of discrete kinetic models for single-component isothermal two-phase flows. The authors show the correspondence between the kinetic model for a non-ideal fluid and the Navier-Stokes equations with a non-ideal equation of state. They also introduce a scaling based on velocity increments to recover the full Navier-Stokes-Korteweg equations. The proposed model is validated on various benchmarks and exhibits thermodynamic and hydrodynamic consistency.
JOURNAL OF FLUID MECHANICS
(2022)
Review
Computer Science, Interdisciplinary Applications
S. A. Hosseini, M. Atif, S. Ansumali, I. V. Karlin
Summary: In the late 90's and early 2000's, the concept of using a discrete H theorem and Lyapunov functionals as a way to ensure stability of lattice Boltzmann solvers brought about a paradigm shift in their construction and opened up new discussions and perspectives. The entropic construction, which introduced a discrete entropy functional and enforced an H-theorem, proved to be effective in stabilizing lattice Boltzmann solvers in various applications including weakly compressible, fully compressible, and multi-phase flows. In this review, we discuss the basic building blocks of the entropic lattice Boltzmann method and its extension to multiphase and compressible flows.
COMPUTERS & FLUIDS
(2023)
Article
Computer Science, Interdisciplinary Applications
Ehsan Reyhanian, Benedikt Dorschner, Ilya Karlin
Summary: In this exploratory study, shock-capturing schemes are applied to simulate compressible flows with shock waves and discontinuities. The model is based on the semi-Lagrangian method and employs concepts like total variation diminishing and weighted essentially non-oscillatory schemes to capture the discontinuities and shock waves. The results show that the reconstruction schemes effectively remove oscillations at the shock wave location, allowing for stable simulations of compressible benchmarks. The numerical properties of the reconstruction schemes, such as spectral analysis and order of accuracy, are also discussed.
COMPUTERS & FLUIDS
(2023)
Article
Physics, Fluids & Plasmas
N. G. Kallikounis, B. Dorschner, I. V. Karlin
Summary: The study utilizes the particles-on-demand method to simulate compressible flows with strong discontinuities in density, pressure, and velocity. The method is modified through regularization by Grad's projection and reference frame transformations, as well as the implementation of a finite-volume scheme to improve stability, accuracy, and conservation of mass, momentum, and energy. The proposed model demonstrates excellent performance in various benchmarks, surpassing the limitations of other lattice Boltzmann-like approaches to compressible flows.
Article
Physics, Fluids & Plasmas
N. G. Kallikounis, B. Dorschner, I. Karlin
Summary: A multi-scale lattice Boltzmann scheme is proposed to adaptively refine particles' velocity space, efficiently coupling different velocity sets of lower and higher order. The scheme shows flexibility in model selection and reduction in computational requirements, validated in various flow setups.
Article
Mathematics, Interdisciplinary Applications
Ehsan Reyhanian, Benedikt Dorschner, Ilya Karlin
Summary: The study presents a kinetic model for compressible non-ideal fluids that imposes local thermodynamic pressure through rescaling particle velocities for full thermodynamic consistency. The model, which is Galilean invariant, treats mass, momentum, and energy as local conservation laws. Benchmark simulations demonstrate accurate and robust performance across different scenarios, showing excellent agreement with theoretical analysis and experimental correlations. The model is capable of operating in the entire phase diagram, including super- and sub-critical regimes, and inherently captures phase-change phenomena.
Article
Physics, Fluids & Plasmas
E. Reyhanian, B. Dorschner, I. Karlin
Article
Physics, Fluids & Plasmas
M. H. Saadat, F. Boesch, I. Karlin