Article
Computer Science, Interdisciplinary Applications
Dominik Wilde, Andreas Kraemer, Mario Bedrunka, Dirk Reith, Holger Foysi
Summary: This study demonstrates that using velocity sets derived from cubature rules can improve the accuracy and efficiency of weakly and fully compressible off-lattice Boltzmann simulations.
JOURNAL OF COMPUTATIONAL SCIENCE
(2021)
Article
Mechanics
Yangyang Shi, Xiaowen Shan
Summary: Research shows that by using a phenomenological collision model along with relaxation rates obtained from the collision term and molecular model, lattice Boltzmann method can produce accurate results in simulating fluid dynamics problems, with significant impacts of relaxation rates of higher moments as the Knudsen number increases. This suggests that properly tuned relaxation rates in the collision model could potentially mimic the behavior of arbitrary collision kernels.
Article
Mechanics
Dejia Zhang, Aiguo Xu, Yudong Zhang, Yanbiao Gan, Yingjun Li
Summary: This paper develops Discrete Boltzmann Models (DBMs) based on the ellipsoidal statistical Bhatnagar-Gross-Krook model to study non-equilibrium high-speed compressible flows that have various applications in engineering and science. Numerical tests demonstrate the model's ability to capture flow structures and TNE effects at different orders. The study is significant for understanding the behavior of complex fluid systems and choosing an appropriate fluid model to account for desired TNE effects.
Article
Engineering, Mechanical
Xiaoyong Wang, Qizhen Hong, Yuan Hu, Quanhua Sun
Summary: Due to the uncertainties in empirical assumptions, the widely-used two-temperature models for hypersonic nonequilibrium flow lack accuracy. To address this, the modified Macheret-Fridman model based on the correction method of the modified Marrone-Treanor model is developed. Several test cases are used to evaluate the accuracy of the modified and widely-used two-temperature models. The study shows that the correction method significantly improves the accuracy of the widely-used two-temperature models and highlights the importance of considering dissociation rates, vibration-dissociation coupling effect, and the non-Boltzmann effect in modeling highly nonequilibrium dissociating flows.
ACTA MECHANICA SINICA
(2023)
Article
Mechanics
Siqi Yao, Fei Fei, Peng Luan, Eunji Jun, Jun Zhang
Summary: The performances of simplified Bhatnagar-Gross-Krook (BGK) models in highly nonequilibrium flows are uncertain. The ellipsoidal statistical BGK (ES-BGK) model outperforms the Shakhov BGK (S-BGK) model in Fourier flow, while the S-BGK model performs better in Couette flow and shock wave. However, both ES-BGK and S-BGK models deviate from the Boltzmann solutions as the Knudsen number or Mach number increases. To improve the performance, the S-BGK model is extended by adding more high-order moments, resulting in the S-BGK+ model with better performance across various flow regimes.
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
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, Multidisciplinary
Junjie Ren, Shengzhen Wang, Xiaoxue Liu
Summary: In this study, an axisymmetric lattice Boltzmann model was developed to simulate microcylindrical Couette gas flows in the slip regime and transition regime. By introducing local effective Knudsen numbers, the effect of Knudsen layers for transition flows was successfully considered.
Article
Computer Science, Interdisciplinary Applications
Maciej Matyka, Michal Dzikowski
Summary: The study simplified the Lattice Boltzmann Method algorithm by assuming constant numerical viscosity and conducted simulations to test it. The results showed that the new method is simpler and less error-prone in implementation, requiring less working memory in low Reynolds number flows but less efficient in multiphase flows. Therefore, further extension and the moments-only formulation were proposed to address this issue.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Computer Science, Interdisciplinary Applications
Alessia Abbati, Ya Zhang, William Dempster, Yonghao Zhang
Summary: Diffuse-interface immersed boundary methods have been widely used in complex fluid-structure interaction problems. However, the diffusive effects of the diffuse interface can reduce simulation accuracy, especially in confined geometries. A boundary retraction scheme is proposed to alleviate interface diffusion errors and enhance accuracy.
COMPUTERS & FLUIDS
(2022)
Article
Physics, Fluids & Plasmas
Guanglan Sun, Yanbiao Gan, Aiguo Xu, Yudong Zhang, Qingfan Shi
Summary: The thermodynamic nonequilibrium effects in the coalescence process of two static bubbles under thermal conditions were investigated using a discrete Boltzmann model. The spatial distributions of nonorganized momentum fluxes (NOMFs) during the evolution were analyzed, and it was found that the NOMFs exhibited specific symmetries and changed throughout the process. The study also revealed a high degree of correlation between different physical quantities and provided insights into the kinetics of bubble coalescence.
Article
Computer Science, Software Engineering
Wei Li, Yihui Ma, Xiaopei Liu, Mathieu Desbrun
Summary: This paper proposes a new solver for coupling the incompressible Navier-Stokes equations with a conservative phase-field equation to simulate multiphase flows. The resulting solver shows efficiency, versatility, and reliability in dealing with large density ratios, high Reynolds numbers, and complex solid boundaries.
ACM TRANSACTIONS ON GRAPHICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Simon Gsell, Umberto D'Ortona, Julien Favier
Summary: The accuracy of lattice-Boltzmann method is related to the relaxation time controlling flow viscosity. The two-relaxation-time model can recover the steady Navier-Stokes equations without restrictions on fluid viscosity. In order to simulate incompressible flows, the viscous incompressibility condition needs to be satisfied, and a local incompressibility factor can be defined to control the accuracy of flows involving varying viscosities.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Computer Science, Interdisciplinary Applications
M. Ho, S. Ammar, S. Leclaire, M. Reggio, J-Y Trepanier
Summary: Two lattice Boltzmann method (LBM) models for binary mixture flows were compared numerically, and the results showed that the performance of the two models differs under the incompressible limit and has different influences on the flow behavior under different flow regimes.
INTERNATIONAL JOURNAL OF MODERN PHYSICS C
(2022)
Article
Mathematics, Applied
Xiang Zhao, Liming Yang, Chang Shu
Summary: This paper proposes a novel implicit lattice Boltzmann flux solver for simulating flows around complex geometries. The solver combines dual time-stepping technique and sub-iteration to efficiently simulate unsteady flows. Various simulations were conducted to demonstrate the accuracy and efficiency of the proposed solver, and it was also used to simulate the flow over complex aircraft models in practical engineering applications.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2022)
Article
Engineering, Multidisciplinary
Wei Su, Yonghao Zhang, Lei Wu
Summary: This paper introduces a general synthetic iterative scheme (GSIS) to efficiently solve multiscale gas dynamics problems and accurately find steady-state solutions for molecular gas flows. Fourier stability analysis and asymptotic analysis demonstrate that GSIS can rapidly converge to steady-state solutions throughout the flow regime, and recover the Navier-Stokes equations when the Knudsen number is small.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Computer Science, Interdisciplinary Applications
Lianhua Zhu, Xingcai Pi, Wei Su, Zhi-Hui Li, Yonghao Zhang, Lei Wu
Summary: The general synthetic iterative scheme (GSIS) has been extended to find the steady-state solution of the nonlinear gas kinetic equation, addressing the issues of slow convergence and requirement of ultra-fine grids in near-continuum flows. The tight coupling of gas kinetic and macroscopic synthetic equations, along with the simplification in constructing higher-order constitutive relations, allows for faster convergence and reduced deviation in the solution. Additionally, the GSIS can be applied to a wide range of engineering applications due to its independence on the specific form of Boltzmann collision operator and compatibility with computational fluid dynamics techniques.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Computer Science, Interdisciplinary Applications
Ya Zhang, Sina Haeri, Guang Pan, Yonghao Zhang
Summary: This study introduces a strong coupling method between the peridynamic model, lattice Boltzmann method, and immersed boundary method to accurately simulate structural deformation and fracture. The coupling is achieved by calculating velocity corrections through solving linear equations, eliminating the need for iterative solutions at each time step.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Computer Science, Interdisciplinary Applications
Qingqing Gu, Minh-Tuan Ho, Yonghao Zhang
Summary: This study evaluated four numerical methods for pore-scale rarefied gas flows, compared their predicted results and computational efficiency, and found that the FD solver is the most efficient.
COMPUTERS & FLUIDS
(2021)
Editorial Material
Mechanics
Ehsan Roohi, Yonghao Zhang
Article
Engineering, Chemical
Nathan Berry, Yonghao Zhang, Sina Haeri
Summary: This study proposes a consistent implementation of Lees-Edwards boundary conditions for the Multi-Sphere Discrete Element Method to mitigate unphysical effects and errors. By comparing with reliable benchmark data and pointing out numerical artefacts of the Naive approach, the proposed consistent implementation is shown to produce data in excellent agreement with benchmark results and literature.
Article
Engineering, Chemical
Ferdin Don Bosco, Yonghao Zhang
Summary: The study explores the rarefied gas flow in ultra-tight porous media, such as shale and high-performance insulation materials, and proposes a novel particle-based solution using the variance-reduced Boltzmann-BGK equation. By developing a parallel solver based on the low variance deviational simulation Monte Carlo method for 3D flows, the research enables pore-scale simulations and provides additional insights into the multi-scale nature of the flow and surface/gas interactions. The computational efficiency and accuracy of the new solver make it a powerful simulation tool for quantifying flow properties of ultra-tight porous media.
TRANSPORT IN POROUS MEDIA
(2021)
Article
Computer Science, Interdisciplinary Applications
Jun Li, Minh Tuan Ho, Matthew K. Borg, Chunpei Cai, Zhi-Hui Li, Yonghao Zhang
Summary: This study compares the computational performance of two methods (DSBGK and DVM) for simulating 3D gas flows in shale rock, finding that DSBGK simulation converges faster, is significantly cheaper, and performs better, making it a practical tool for simulations.
COMPUTERS & FLUIDS
(2021)
Article
Mechanics
Carlos Corral-Casas, Livio Gibelli, Matthew K. Borg, Jun Li, Saad F. K. Al-Afnan, Yonghao Zhang
Summary: This study investigates self-diffusion mechanisms in confined dense fluids under high pressure and nanoscale constraints, finding that the Bosanquet formula can provide a good description of self-diffusion in these conditions. Additionally, it shows that the Einstein self-diffusivity can still be used within Fick's law in certain circumstances.
Article
Mechanics
Baochao Shan, Peng Wang, Runxi Wang, Yonghao Zhang, Zhaoli Guo
Summary: One major challenge in describing nanoscale confined fluid flows is the lack of a boundary condition that can capture molecular-scale slip behaviors. In this study, a molecular-kinetic boundary condition is proposed to model the fluid-surface and fluid-fluid molecular interactions, and is applied to investigate nanoscale Couette and Poiseuille flows. The simulation results reveal unexpected slip behaviors, including the epitaxial layering structure of fluids and the minimum slip length. A new scaling law is proposed for the slip length to account for various physical mechanisms.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Wei Su, Qi Li, Yonghao Zhang, Lei Wu
Summary: The temperature jump problem in rarefied molecular gases is investigated using a one-dimensional heat conduction problem. Analytical formulations for the temperature jump coefficient are derived, and numerical calculations reveal that the temperature jump depends on the thermal relaxation processes. A new formulation is proposed based on the numerical results.
Article
Engineering, Chemical
Chrysovalantis Tsigginos, Jianping Meng, Xiao-Jun Gu, David R. Emerson
Summary: In this study, we investigate the theoretical and computational aspects of coupled lattice Boltzmann-discrete element simulations and propose some improvements to address numerical instabilities. The effect of the timesteps of the discrete element and lattice Boltzmann method on the accuracy of the simulations is also explored.
Article
Computer Science, Interdisciplinary Applications
Alessia Abbati, Ya Zhang, William Dempster, Yonghao Zhang
Summary: Diffuse-interface immersed boundary methods have been widely used in complex fluid-structure interaction problems. However, the diffusive effects of the diffuse interface can reduce simulation accuracy, especially in confined geometries. A boundary retraction scheme is proposed to alleviate interface diffusion errors and enhance accuracy.
COMPUTERS & FLUIDS
(2022)
Article
Engineering, Chemical
Nathan Berry, Yonghao Zhang, Sina Haeri
Summary: Five sources of critical error are identified for binary interactions of particles using the Multi-Sphere Discrete Element Method (MS-DEM), including under-damping, two forms of over-damping error, over-stiffness effects, and force response inconsistencies due to erroneous contact area calculations. Algorithmic issues are found to be the source of over-stiffness effects, one form of over-damping, and the erroneous contact area calculations. The remaining over-damping and under-damping errors are physical in nature. Solutions are proposed which can successfully mitigate all of the identified errors.
Article
Physics, Fluids & Plasmas
Wei Su, Livio Gibelli, Jun Li, Matthew K. Borg, Yonghao Zhang
Summary: A kinetic model is proposed for the nonequilibrium flow of dense gases and is validated through extensive benchmark tests. The model accurately describes the physical properties and transport coefficients of high-density gas systems, as well as the inhomogeneous density distribution near solid boundaries. The model's collision operator includes a relaxation part and an excess part to account for finite-size effects. The model demonstrates its applicability in simulating forced wave propagation in dense gases.
PHYSICAL REVIEW FLUIDS
(2023)