scholarly journals Lattice-Boltzmann Simulation and Experimental Validation of a Microfluidic T-Junction for Slug Flow Generation

2019 ◽  
Vol 3 (2) ◽  
pp. 48
Author(s):  
Volker Paul Schulz ◽  
Nima Abbaspour ◽  
Tobias Baumeister ◽  
Thorsten Röder
Keyword(s):  
Lattice Boltzmann ◽  
Immiscible Fluids ◽  
Microfluidic Channels ◽  
Lattice Boltzmann Simulation ◽  
Flow Generation ◽  
Static Contact ◽  
Bubble Test ◽  
Layered Flow ◽  
Boltzmann Method ◽  
First Time

We investigate the interaction of two immiscible fluids in a head-on device geometry, where both fluids are streaming opposite to each other. The simulations are based on the two-dimensional (2D) lattice Boltzmann method (LBM) using the Rothman and Keller (RK) model. We validate the LBM code with several benchmarks such as the bubble test, static contact angle, and layered flow. For the first time, we simulate a head-on device by forcing periodicity and a volume force to induce the flow. From low to high flow rates, three main flow patterns are observed in the head-on device, which are dripping-squeezing, jetting-shearing, and threading. In the squeezing regime, the flow is steady and the droplets are equal. The jetting-shearing flow is not as stable as dripping-squeezing. Moreover, the formation of droplets is shifted downstream into the main channel. The last flow form is threading, in which the immiscible fluids flow parallel downstream to the outlet. In contrast to other studies, we select larger microfluidic channels with 1-mm channel width to achieve relatively high volumetric fluxes as used in chemical synthesis reactors. Consequently, the capillary number of the flow regimes is smaller than 10−5. In conclusion, the simulation compares well to experimental data.

scholarly journals Lattice Boltzmann Simulation of Natural Convection in an Annulus between a Hexagonal Cylinder and a Square Enclosure

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
L. El Moutaouakil ◽  
Z. Zrikem ◽  
A. Abdelbaki
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Cross Section ◽  
Lattice Boltzmann ◽  
Square Enclosure ◽  
Lattice Boltzmann Simulation ◽  
Laminar Natural Convection ◽  
Heat Transfers ◽  
Boltzmann Method ◽  
Vertical Case

Laminar natural convection in a water filled square enclosure containing at its center a horizontal hexagonal cylinder is studied by the lattice Boltzmann method. The hexagonal cylinder is heated while the walls of the cavity are maintained at the same cold temperature. Two orientations are treated, corresponding to two opposite sides of the hexagonal cross-section which are horizontal (case I) or vertical (case II). For each case, the results are presented in terms of streamlines, isotherms, local and average convective heat transfers as a function of the dimensionless size of the hexagonal cylinder cross-section (0.1≤B≤0.4), and the Rayleigh number (103≤Ra≤106).

scholarly journals Lattice Boltzmann simulation of two-sided lid-driven flow in deep cavities

2015 ◽  
pp. 157-168
Author(s):  
Natasa Lukic ◽  
Predrag Tekic ◽  
Jelena Radjenovic ◽  
Ivana Sijacki
Keyword(s):  
Aspect Ratio ◽  
Flow Pattern ◽  
Lattice Boltzmann ◽  
Reynolds Numbers ◽  
Critical Aspect ◽  
Symmetric Flow ◽  
Primary Vortex ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
Deep Cavities

The present study is concerned with two-sided lid-driven incompressible flow in rectangular, deep cavities applying lattice Boltzmann method. After validating the code for the square cavity, solutions for cavities with an aspect ratio 1.5 and 4 were obtained for the Reynolds numbers of 100, 400, 1000 and 3200. The influence of the Reynolds number and aspect ratio on the flow pattern and on the characteristics of vortices inside the cavity was studied. Symmetric flow pattern was obtained for all investigated cases. The middle of the cavity is mostly influenced by the increase in the aspect ratio. Critical aspect ratio, at which the birth of a primary vortex in the middle of the cavity takes place, was determined to be between 2.7 and 2.725.

scholarly journals Lattice Boltzmann simulation of liquid falling on horizontal rectangular pillar arrays

2021 ◽  
Vol 321 ◽  
pp. 01014
Author(s):  
Makoto Sugimoto ◽  
Tatsuya Miyazaki ◽  
Zelin Li ◽  
Masayuki Kaneda ◽  
Kazuhiko Suga
Keyword(s):  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Phase Field Model ◽  
Flow Simulation ◽  
High Viscosity ◽  
Two Phase ◽  
Lattice Boltzmann Simulation ◽  
Pillar Arrays ◽  
Boltzmann Method ◽  
Behavior Characteristic

Stator coils of automobiles in operation generate heat and are cooled by a coolant poured from above. Since the behavior characteristic of the coolant poured on the coils is not clarified yet due to its complexity, the three-dimensional two-phase flow simulation is conducted. In this study, as a steppingstone to the simulation of the liquid falling on the actual coils, the coils are modelled with horizontal rectangular pillar arrays whose governing parameters can be easily changed. The two-phase flows are simulated using the lattice Boltzmann method and the phase-field model, and the effects of the governing parameters, such as the physical properties of the cooling liquid, the wettability, and the gap between the pillars, on the wetting area are investigated. The results show that the oil tends to spread across the pillars because of its high viscosity. Moreover, the liquid spreads quickly when the contact angle is small. In the case that the pillars are stacked, the wetting area of the inner pillars is larger than that of the exposed pillars.

Modeling of collapsing cavitation bubble near solid wall by 3D pseudopotential multi-relaxation-time lattice Boltzmann method

2017 ◽  
Vol 232 (3) ◽  
pp. 445-456 ◽  
Author(s):  
Minglei Shan ◽  
Yu Yang ◽  
Hao Peng ◽  
Qingbang Han ◽  
Changping Zhu
Keyword(s):  
Relaxation Time ◽  
Lattice Boltzmann ◽  
Cavitation Bubble ◽  
Solid Wall ◽  
Three Dimensional ◽  
Lattice Boltzmann Model ◽  
Bubble Collapse ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
Boltzmann Model

Understanding the dynamic characteristic of the cavitation bubble near a solid wall is a fundamental issue for the bubble collapse application and prevention. In the present work, an improved three-dimensional multi-relaxation-time pseudopotential lattice Boltzmann model is adopted to investigate the cavitation bubble collapse near the solid wall. With respect to thermodynamic consistency, Laplace law verification, the three-dimensional pseudopotential multi-relaxation-time lattice Boltzmann model is investigated. By the theoretical analysis, it is proved that the model can be regarded as a solver of the Rayleigh–Plesset equation, and confirmed by comparing the results of the lattice Boltzmann simulation and the Rayleigh–Plesset equation calculation for the case of cavitation bubble collapse in the infinite medium field. The bubble collapse near the solid wall is modeled using the improved pseudopotential multi-relaxation-time lattice Boltzmann model. We find the lattice Boltzmann simulation and the experimental results have the same dynamic process by comparing the bubble profiles evolution. Form the pressure field and the velocity field evolution it is found that the tapered higher pressure region formed near the top of the bubble is a crucial driving force inducing the bubble collapse. This exploratory research demonstrates that the lattice Boltzmann method is an alternative tool for the study of the interaction between collapsing cavitation bubble and matter.

Simulation of Heat Transfer With LBM and Lagrangian Methods for Microfluidic Applications

2005 ◽  
Author(s):  
Nishitha Thummala ◽  
Dimitrios V. Papavassiliou
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Lattice Boltzmann ◽  
Constant Heat Flux ◽  
Fully Developed Flow ◽  
Thermal Boundary Conditions ◽  
Lattice Boltzmann Simulation ◽  
Lagrangian Tracking ◽  
Boltzmann Method ◽  
Single Flow

This work presents a Lagrangian approach to simulate convective heat transfer in small scales. The fully developed flow field, simulated by a Lattice Boltzmann Method, is combined with Lagrangian tracking of thermal markers to determine the behavior of an instantaneous scalar line source located at the wall of a channel. The resulting probability density functions are used to calculate the behavior of continuous line sources of heat at the wall of the channel, as well as the temperature for the case of constant temperature or constant heat flux from the wall. This method is resourceful in terms of computational efficiency, in that it can be used to simulate various thermal boundary conditions and Prandtl number fluids with a single flow field resulting from a Lattice Boltzmann simulation.

Lattice Boltzmann Simulation of Flow and Heat Transfer Characteristics in a Symmetrically Bifurcated Microchannel

2004 ◽  
Author(s):  
Keqiang Xing ◽  
Yong Tao
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Constant Heat Flux ◽  
Lattice Boltzmann Model ◽  
Straight Tube ◽  
Lattice Boltzmann Simulation ◽  
Flux Boundary Conditions ◽  
Boltzmann Method ◽  
Thermal Lattice Boltzmann ◽  
Transfer Problems

The lattice Boltzmann method (LBM) as a relatively new numerical scheme has recently achieved considerable success in simulating fluid flows and associated transport phenomena. However, application of this method to heat transfer problems has been at a stage of infancy. In this work, a thermal lattice Boltzmann model is employed to simulate a two-dimensional, steady flow in a symmetric bifurcation under constant temperature and constant heat flux boundary conditions. The bifurcation effects on the heat transfer and fluid flow are investigated and comparisons are made with the straight tube. Also, different bifurcation angles are simulated and the results are compared with the work of the other researchers.

scholarly journals A lattice Boltzmann simulation of oblique impact of a single rain droplet on super-hydrophobic surface with randomly distributed rough structures

2020 ◽  
Vol 15 (3) ◽  
pp. 443-449
Author(s):  
Zhang Shusheng ◽  
Lu Hao ◽  
Zhang Li-Zhi ◽  
Riffat Saffa ◽  
Ure Zafer ◽  
...  
Keyword(s):  
Lattice Boltzmann ◽  
Contact Time ◽  
Hydrophobic Surface ◽  
Impact Angle ◽  
Oblique Impact ◽  
Building Structures ◽  
Pinning Effect ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
The Impact

Abstract In this paper, oblique impact of a single rain droplet on super-hydrophobic surface with randomly distributed rough structures was investigated by lattice Boltzmann method. The effects of the impact angle of the droplet as well as the skewness and kurtosis of rough surface on the bouncing ability of the droplet were in this paper. It was found that the oblique impact can effectively reduce the contact time in the process of droplet bouncing off, because the energy consumption caused by the pinning effect is reduced. Moreover, the contact time most possibly reaches the shortest when the impact angle is 45°. Decreasing the skewness and keeping the kurtosis around 4.0 can enhance the bouncing ability during the droplet oblique impact on randomly distributed rough surfaces. The results are useful for the design of building structures.

Lattice Boltzmann Simulation of Particle Motion in Binary Immiscible Fluids

2015 ◽  
Vol 18 (3) ◽  
pp. 757-786 ◽  
Author(s):  
Yu Chen ◽  
Qinjun Kang ◽  
Qingdong Cai ◽  
Moran Wang ◽  
Dongxiao Zhang
Keyword(s):  
Lattice Boltzmann ◽  
Particle Motion ◽  
Mass Conservation ◽  
Immiscible Fluids ◽  
Lattice Boltzmann Model ◽  
Lattice Boltzmann Simulation ◽  
Suspension Model ◽  
Wetting Model ◽  
Boltzmann Model ◽  
The Impact

AbstractWe combine the Shan-Chen multicomponent lattice Boltzmann model and the link-based bounce-back particle suspension model to simulate particle motion in binary immiscible fluids. The impact of the slightly mixing nature of the Shan-Chen model and the fluid density variations near the solid surface caused by the fluid-solid interaction, on the particle motion in binary fluids is comprehensively studied. Our simulations show that existing models suffer significant fluid mass drift as the particle moves across nodes, and the obtained particle trajectories deviate away from the correct ones. A modified wetting model is then proposed to reduce the non-physical effects, and its effectiveness is validated by comparison with existing wetting models. Furthermore, the first-order refill method for the newly created lattice node combined with the new wetting model significantly improves mass conservation and accuracy.

Lattice Boltzmann Simulation of Miscible Fluids Displacement in the Pore Space

2012 ◽  
Author(s):  
Yiqiang Liang ◽  
Yongchen Song ◽  
Weizhong Li
Keyword(s):  
Lattice Boltzmann ◽  
Pore Space ◽  
Transitional Period ◽  
Miscible Fluids ◽  
Physical Mechanisms ◽  
Whole Process ◽  
Promising Tool ◽  
Lattice Boltzmann Simulation ◽  
Boltzmann Method ◽  
Stable Stage

In this work, we simulate natural miscible process and miscible fluids displacement in pore space by using lattice-Boltzmann method. In the natural miscible case, the results including concentration profile and thickness of miscible zone agree well with analytical solutions, which verifies the model’s reliability and veracity. The viscosity ratio is also taken into account to study its influence on the miscible process. Furthermore, we apply pressure boundary at inlet and outlet of the channel to study the displacement of miscible fluids. The whole process, in general, is divided into three phases: fluid flow rate increasing driven by pressure gradient, transitional period, and relatively stable stage. And we carefully give each phase explanations of physical mechanisms. The numerical results provide a good understanding of the mechanisms of miscible fluids displacement and confirm that the LBM can be a promising tool for investigating miscible fluids behavior.

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