scholarly journals Direct Numerical Simulation of Sediment Transport in Turbulent Open Channel Flow Using the Lattice Boltzmann Method

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 217
Author(s):  
Liangquan Hu ◽  
Zhiqiang Dong ◽  
Cheng Peng ◽  
Lian-Ping Wang
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Open Channel ◽  
Volume Fraction ◽  
Homogeneous Distribution ◽  
Wall Region ◽  
Particle Volume ◽  
Volume Fractions ◽  
Sediment Particles ◽  
Boltzmann Method

The lattice Boltzmann method is employed to conduct direct numerical simulations of turbulent open channel flows with the presence of finite-size spherical sediment particles. The uniform particles have a diameter of approximately 18 wall units and a density of ρp=2.65ρf, where ρp and ρf are the particle and fluid densities, respectively. Three low particle volume fractions ϕ=0.11%, 0.22%, and 0.44% are used to investigate the particle-turbulence interactions. Simulation results indicate that particles are found to result in a more isotropic distribution of fluid turbulent kinetic energy (TKE) among different velocity components, and a more homogeneous distribution of the fluid TKE in the wall-normal direction. Particles tend to accumulate in the near-wall region due to the settling effect and they preferentially reside in low-speed streaks. The vertical particle volume fraction profiles are self-similar when normalized by the total particle volume fractions. Moreover, several typical transport modes of the sediment particles, such as resuspension, saltation, and rolling, are captured by tracking the trajectories of particles. Finally, the vertical profiles of particle concentration are shown to be consistent with a kinetic model.

scholarly journals Heat transfer enhancement inside channel by using the Lattice Boltzmann Method

2020 ◽  
pp. 96-96
Author(s):  
Abchouyeh Asadi ◽  
Ganaoui El ◽  
Rasul Mohebbi ◽  
Mohammad Zarrabi ◽  
Omid Fard ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Flow Field ◽  
Lattice Boltzmann Method ◽  
Forced Convection ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Hybrid Nanofluid ◽  
Boltzmann Method

In this study, the Lattice Boltzmann Method (LBM) is employed in order to examine the fluid flow and forced convection heat transfer inside a two-dimensional horizontal channel with and without obstacles. In order to enhance the heat and thermal energy transfer within the channel, different obstacle arrangements are posed to the flow field and heat transfer with the purpose of studying their sensitivity to these changes. The results indicate that, when the value of the Reynolds number is maximum, the maximum average Nusselt numbers happens on the lower wall (Case 4). The paper extends the topic to the use of nanofluids to introduce a possibility to enhancement of the heat transfer in the channel with an array of the obstacles with forced convection. For this purpose, the AgMgO/water micropolar hybrid nanofluid is used, and the volume fraction of the nanoparticle (50% Ag and 50% MgO by volume) is set between 0 and 0.02. The results showed that, when the hybrid nanofluid is used instead of a typical nanofluid, the rate of the heat transfer inside the channel increases, especially for the high values of the Reynolds number, and the volume fraction of the nanoparticles. Increasing the volume fraction of the nanoparticles increase the local Nusselt number ( 1.17-fold). It is shown that the type of obstacle arrangement and the specific nanofluid can exerts significant effects on the characteristics of the flow field and heat transfer in the channel. This study provides a platform for using the LBM to examine fluid flow through discrete obstacles in offset positions.

3D investigation of natural convection of nanofluids in a curved boundary enclosure applying lattice Boltzmann method

2018 ◽  
Vol 28 (8) ◽  
pp. 1827-1844 ◽  
Author(s):  
Mehdi Hosseini Abadshapoori ◽  
Mohammad Hassan Saidi
Keyword(s):  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Design Methodology ◽  
Volume Fraction ◽  
Relaxation Times ◽  
Simple Algorithm ◽  
Curved Boundaries ◽  
Content Type ◽  
Boltzmann Method

Purpose The purpose of this paper is to investigate the natural convection behavior of nanofluids in an enclosure. The enclosure is a 3D capsule with curved boundaries filled with TiO2-water nanofluid. Design/methodology/approach In this paper, a multiple relaxation times lattice Boltzmann method (MRT-LBM) has been used. Two-component LBM has been conducted to consider the interaction forces between nanoparticles and the base fluid. Findings Results show that the enhanced Nusselt number (Nu*) increases with the increase in volume fraction of nanoparticles (ϕ) and Ra number and decrease of nanoparticle size (λ). Additionally, the findings indicate that increasing volume fraction beyond a certain value decreases Nu*. Originality/value This paper presents a MRT model of lattice Boltzmann in a 3D curved enclosure. A correlation is also presented based on the current results for Nu* depending on Ra number, volume fraction and size of nanoparticles. Furthermore, a comparison for the convergence rate and accuracy of this model and the SIMPLE algorithm is presented.

Numerical study of natural convection of nanofluid in a semi-circular cavity with lattice Boltzmann method

2019 ◽  
Vol 30 (5) ◽  
pp. 2625-2637 ◽  
Author(s):  
Hanieh Nazarafkan ◽  
Babak Mehmandoust ◽  
Davood Toghraie ◽  
Arash Karimipour
Keyword(s):  
Natural Convection ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Numerical Study ◽  
Solid Volume Fraction ◽  
Circular Cavity ◽  
Cu Nanoparticles ◽  
Content Type ◽  
Boltzmann Method

Purpose This study aims to apply the lattice Boltzmann method to investigate the natural convection flows utilizing nanofluids in a semicircular cavity. The fluid in the cavity is a water-based nanofluid containing Al2O3 or Cu nanoparticles. Design/methodology/approach The study has been carried out for the Rayleigh numbers from 104 to 106 and the solid volume fraction from 0 to 0.05. The effective thermal conductivity and viscosity of nanofluid are calculated by the models of Chon and Brinkman, respectively. The effects of solid volume fraction on hydrodynamic and thermal characteristics are investigated and discussed. The averaged and local Nusselt numbers, streamlines, temperature contours for different values of solid volume fraction and Rayleigh number are illustrated. Findings The results indicate that more solid volume fraction corresponds to more averaged Nusselt number for both types of nanofluids. It is also found that the effects of solid volume fraction of Cu are stronger than those of Al2O3. Originality/value Numerical study of natural convection of nanofluid in a semi-circular cavity with lattice Boltzmann method in the presence of water-based nanofluid containing Al2O3 or Cu nanoparticles.

Lattice Boltzmann Method Simulation of Turbulent Indoor Airflow Using Hybrid LES/RANS Model

2017 ◽  
Author(s):  
H. Sajjadi ◽  
M. Salmanzadeh ◽  
G. Ahmadi ◽  
S. Jafari
Keyword(s):  
Lattice Boltzmann Method ◽  
Hybrid Model ◽  
Turbulence Model ◽  
Lattice Boltzmann ◽  
Large Scale ◽  
Computational Time ◽  
Wall Region ◽  
Rans Model ◽  
Boltzmann Method ◽  
Near Wall

In this study the hybrid RANS/LES turbulence model within the framework of the Lattice Boltzmann method (LBM) was used to study turbulent indoor airflows. In this approach the near wall region was simulated by the RANS model, while the bulk of the domain was analyzed using the LES model with the LBM approach. In the near wall layer where RANS was used, the k-ε turbulence model was employed. For the k-ε turbulence model in conjunction with the LBM two population balance equations for k and ε were used. The present simulation results for the airflow showed good agreement with the experimental data and the earlier numerical results for the hybrid RANS/LES. The results showed that the hybrid model properly predicted the large scale turbulence fluctuation velocities in the bulk of the flow region. In addition, the computational time for the hybrid model is less than that of the LES method.

Analysis of drag and virtual mass forces in bubbly suspensions using an implicit formulation of the lattice Boltzmann method

2002 ◽  
Vol 452 ◽  
pp. 61-96 ◽  
Author(s):  
K. SANKARANARAYANAN ◽  
X. SHAN ◽  
I. G. KEVREKIDIS ◽  
S. SUNDARESAN
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Computational Cost ◽  
Computational Experiments ◽  
Mass Force ◽  
Virtual Mass ◽  
Time Step ◽  
Mass Coefficient ◽  
Boltzmann Method

We present closures for the drag and virtual mass force terms appearing in a two-fluid model for flow of a mixture consisting of uniformly sized gas bubbles dispersed in a liquid. These closures were deduced through computational experiments performed using an implicit formulation of the lattice Boltzmann method with a BGK collision model. Unlike the explicit schemes described in the literature, this implicit implementation requires iterative calculations, which, however, are local in nature. While the computational cost per time step is modestly increased, the implicit scheme dramatically expands the parameter space in multiphase flow calculations which can be simulated economically. The closure relations obtained in our study are limited to a regular array of uniformly sized bubbles and were obtained by simulating the rise behaviour of a single bubble in a periodic box. The effect of volume fraction on the rise characteristics was probed by changing the size of the box relative to that of the bubble. While spherical bubbles exhibited the expected hindered rise behaviour, highly distorted bubbles tended to rise cooperatively. The closure for the drag force, obtained in our study through computational experiments, captured both hindered and cooperative rise. A simple model for the virtual mass coefficient, applicable to both spherical and distorted bubbles, was also obtained by fitting simulation results. The virtual mass coefficient for isolated bubbles could be correlated with the aspect ratio of the bubbles.

scholarly journals Study of Cavitation Bubble Collapse near a Wall by the Modified Lattice Boltzmann Method

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1439 ◽  
Author(s):  
Yunfei Mao ◽  
Yong Peng ◽  
Jianmin Zhang
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Cavitation Bubble ◽  
Morphological Changes ◽  
Bubble Collapse ◽  
Wall Region ◽  
Wall Surface ◽  
Cavitation Bubbles ◽  
Boltzmann Method ◽  
Near Wall

In this paper, an improved lattice Boltzmann Shan‒Chen model coupled with Carnahan-Starling equation of state (C-S EOS) and the exact differential method (EDM) force scheme is used to simulate the cavitation bubble collapse in the near-wall region. First, the collapse of a single cavitation bubble in the near-wall region was simulated; the results were in good agreement with the physical experiment and the stability of the model was verified. Then the simulated model was used to simulate the collapse of two cavitation bubbles in the near-wall region. The main connection between the two cavitation bubble centre lines and the wall surface had a 45° angle and parallel and the evolution law of cavitation bubbles in the near-wall region is obtained. Finally, the effects of a single cavitation bubble and double cavitation bubble on the wall surface in the near-wall region are compared, which can be used to study the method to reduce the influence of cavitation on solid materials in practical engineering. The cavitation bubble collapse process under a two-dimensional pressure field is visualized, and the flow field is used to describe the morphological changes of cavitation bubble collapse in the near-wall region. The improved lattice Boltzmann Method (LBM) Shan‒Chen model has many advantages in simulating cavitation problems, and will provide a reference for further simulations.

Investigation of open channel flow with unsubmerged rigid vegetation by the lattice Boltzmann method

2019 ◽  
Vol 32 (4) ◽  
pp. 771-783
Author(s):  
He-fang Jing ◽  
Yin-juan Cai ◽  
Wei-hong Wang ◽  
Ya-kun Guo ◽  
Chun-guang Li ◽  
...  
Keyword(s):  
Lattice Boltzmann Method ◽  
Channel Flow ◽  
Lattice Boltzmann ◽  
Open Channel ◽  
Open Channel Flow ◽  
Rigid Vegetation ◽  
Boltzmann Method

Natural Convection Flow Simulation of Nanofluid in a Square Cavity Using an Incompressible Generalized Lattice Boltzmann Method

2012 ◽  
Vol 329 ◽  
pp. 69-79 ◽  
Author(s):  
Ahmad Reza Rahmati ◽  
Sina Niazi ◽  
Mehrdad Naderi Beni
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Flow Simulation ◽  
Hydrodynamic Characteristics ◽  
Convection Flow ◽  
Square Cavity ◽  
Boltzmann Method

In this Paper, the Heat Transfer Performance in an Enclosure Including Nanofluids Is Studied. the Velocity Field Is Solved by an Incompressible Generalized Lattice Boltzmann Method and Heat Transfer Is Simulated Using Single-Relaxation-Time Lattice Boltzmann Method. the Hydrodynamics and Thermal Fields Are then Coupled Together Using the Boussinesq Approximation. the Fluid in the Square Cavity Is a Cu-Water Nanofluid. the Effects of Grashof Number and Solid Volume Fraction on Thermal and Hydrodynamic Characteristics Are Investigated. the Results Obtained Clearly Show that Heat Transfer Enhancement Is Possible Using Nanofluids in Comparison to Conventional Fluids. Comparisons with Previously Published Works Are Performed and Found to Be in Excellent Agreement with Existing Data.

Simulation of turbulent duct flow by employing shear-improved Smagorinsky model accompanied by forced generalized lattice Boltzmann method

2013 ◽  
Vol 24 (1) ◽  
pp. 86-102 ◽  
Author(s):  
S. Jafari ◽  
M. Rahnama ◽  
E. Jahanshahi Javaran
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Secondary Flows ◽  
Published Data ◽  
Wall Region ◽  
Duct Flow ◽  
Smagorinsky Model ◽  
Content Type ◽  
Turbulent Duct Flow ◽  
Boltzmann Method

Purpose – The present work aims to deal with simulation of turbulent duct flow using generalized lattice Boltzmann equation (GLBE) in which large eddy simulation was employed. Design/methodology/approach – The sub-grid scale turbulence effects were simulated through a shear-improved Smagorinsky model (SISM) which is capable of predicting turbulent near wall region accurately without any wall function. Computations were done for fully developed turbulent square duct flow at Ret=300, based on duct width and average friction velocity. Findings – Results obtained for turbulent duct flow reveal that the GLBE in conjunction with SISM is able to correctly predict the existence of secondary flows and the computed detailed structure of first- and second-order statistics of main and secondary motions. The methodology is validated by comparing with previously published data. It is concluded that such framework is capable of predicting accurate results for turbulent duct flow. In addition, the operations in the present method are local; it can be easily programmed for parallel machines. Originality/value – The numerical method, including generalized lattice Boltzmann method with forcing term and implementation of SISM in GLBE, is used for the first time to simulate turbulent duct flow.

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