Lattice Boltzmann Simulation of Drops in a Shear Flow

2003 ◽  
Author(s):  
Naoki Takada ◽  
Akio Tomiyama ◽  
Shigeo Hosokawa
Keyword(s):  
Shear Flow ◽  
Lattice Boltzmann ◽  
Fluid Model ◽  
Phase Interface ◽  
Vof Method ◽  
Numerical Results ◽  
Repulsive Interaction ◽  
Parallel Plates ◽  
Number Density ◽  
Two Phase

In this paper, we present simulation results of two- and three-dimensional motions of drops in a shear flow based on the lattice Boltzmann method (LBM), where a macroscopic fluid flow results from averaging collisions and propagations of mesoscopic particles. The binary fluid model in LBM used here can reproduce two-phase interface in a self-organizing way by repulsive interaction between particles consistent with the van der Waals-Cahn-Hilliard free energy theory. A finite difference scheme is applied to the lattice-Boltzmann equations governing time evolution of velocity distributions of particle number density. When a drop is suspended in an immiscible second liquid with the same mass and viscosity between moving parallel plates, the numerical results of deformation of drop agree with theoretical solutions and previous numerical results obtained by the volume-of-fluid (VOF) method. Breakup motions of drops in LBM are also reasonable in comparison with the critical Reynolds and capillary numbers predicted by the VOF method. In the simulations of two-drop interaction, it is shown that the breakup motion depends on not only number density of drops but also initial positioning of their volumetric center away from a halfway cross section between the plates.

Simulation of Interface Deformation in Shear Flow Using Binary Fluid Lattice Boltzmann Model

2002 ◽  
Author(s):  
Naoki Takada ◽  
Akio Tomiyama ◽  
Shigeo Hosokawa
Keyword(s):  
Shear Flow ◽  
Lattice Boltzmann ◽  
Fluid Model ◽  
Kinetic Equations ◽  
Three Dimensional ◽  
Lattice Boltzmann Model ◽  
Repulsive Interaction ◽  
Binary Fluid ◽  
Two Phases ◽  
Boltzmann Method

In this paper, we describes the simulations of two- and three-dimensional interfacial motions in shear flow based on the lattice Boltzmann method (LBM), in which a macroscopic fluid flow results from averaging collision and translation of mesoscopic particles and an interface can be reproduced in a self-organizing way by repulsive interaction between particles. A new scheme in the binary fluid model is proposed to simulate motions of immiscible two phases with different mass densities, and examined in numerical analysis of bubble motions under gravity in a circular tube and deformation of bubble under shear stress. For higher Reynolds numbers, a finite difference-based lattice Boltzmann scheme is applied to the kinetic equations of particle to improve numerical stability, which can capture break-up motions of bubble. Parallel computing in LBM is also discussed briefly for efficient speeding up.

Numerical Analysis of Two-Phase Pipe Flow of Liquid Helium Using Multi-Fluid Model

2001 ◽  
Vol 123 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Jun Ishimoto ◽  
Mamoru Oike ◽  
Kenjiro Kamijo
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
Liquid Helium ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Numerical Results ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Normal Fluid

The two-dimensional characteristics of the vapor-liquid two-phase flow of liquid helium in a pipe are numerically investigated to realize the further development and high performance of new cryogenic engineering applications. First, the governing equations of the two-phase flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model are presented and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the two-phase flow of liquid helium is shown in detail, and it is also found that the phase transition of the normal fluid to the superfluid and the generation of superfluid counterflow against normal fluid flow are conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase. According to these theoretical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained should contribute to the realization of advanced cryogenic industrial applications.

LATTICE BOLTZMANN SIMULATIONS OF DROP–DROP INTERACTIONS IN TWO-PHASE FLOWS

2005 ◽  
Vol 16 (01) ◽  
pp. 25-44 ◽  
Author(s):  
KANNAN N. PREMNATH ◽  
JOHN ABRAHAM
Keyword(s):  
Shear Flow ◽  
Lattice Boltzmann ◽  
Flow Model ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Drop Deformation ◽  
Simple Shear Flow ◽  
Two Phase ◽  
Lattice Boltzmann Simulations ◽  
Boltzmann Method

In this paper, three-dimensional computations of drop–drop interactions using the lattice Boltzmann method (LBM) are reported. The LBM multiphase flow model employed is evaluated for single drop problems and binary drop interactions. These include the verification of Laplace–Young relation for static drops, drop oscillations, and drop deformation and breakup in simple shear flow. The results are compared with experimental data, analytical solutions and numerical solutions based on other computational methods, as applicable. Satisfactory agreement is shown. Initial studies of drop–drop interactions involving the head-on collisions of drops in quiescent medium and off-center collision of drops in the presence of ambient shear flow are considered. As expected, coalescence outcome is observed for the range of parameters studied.

AMADEUS Project and Microscopic Simulation of Boiling Two-Phase Flow by the Lattice-Boltzmann Method

1997 ◽  
Vol 08 (04) ◽  
pp. 843-858 ◽  
Author(s):  
Yasuyoshi Kato ◽  
Koji Kono ◽  
Takeshi Seta ◽  
Daniel Martínez ◽  
Shiyi Chen
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
Lattice Boltzmann ◽  
Bubble Dynamics ◽  
Two Phase Flow ◽  
Phase Interface ◽  
Lattice Boltzmann Model ◽  
Phase Flow ◽  
Two Phase ◽  
Boltzmann Model

A two-dimensional lattice-Boltzmann model with a hexagonal lattice is developed to simulate a boiling two-phase flow microscopically. Liquid-gas phase transition and bubble dynamics, including bubble formation, growth and deformation, are modeled by using an interparticle potential based on the van der Waals equation of state. Thermohydrodynamics is incorporated into the model by adding extra velocities to define temperature. The lattice-Boltzmann model is solved by a finite difference scheme so that numerical stability can be ensured at large discontinuity across the liquid-gas phase boundary and the narrow phase interface thickness can be attained. It is shown from numerical simulations that the model has the ability to reproduce phase transition, bubble dynamics and thermohydrodynamics while assuring numerical instability and narrow phase interface.

Application of Number Density Transport Equation for the Recovery of Consistency in Multi-Field Model

2003 ◽  
Author(s):  
Akio Tomiyama ◽  
Naoki Shimada ◽  
Hiroyuki Asano
Keyword(s):  
Numerical Experiment ◽  
Transport Equation ◽  
Shape Factor ◽  
Field Model ◽  
Fluid Model ◽  
Fluid Models ◽  
Number Density ◽  
Two Phase ◽  
Closure Relations ◽  
Dispersed Flows

It is demonstrated through a thought numerical experiment that a conventional two- or multi-fluid model suffers from an inconsistency problem, by which it would fail in accurately predicting two-phase dispersed flows even with reliable closure relations for interfacial transfer terms. To overcome the inconsistency, a numerical method based on a number density transport equation and a shape factor for a fluid or solid particle is proposed. The (N+2)-field model (NP2 model) proposed in our previous studies [1]–[3] is adopted as the basis of the proposed method. It is confirmed that the method gives better predictions than conventional multi-fluid models and recovers the consistency.

Numerical analysis of blockage effects on the flow between parallel plates by using Lattice Boltzmann method

2020 ◽  
Author(s):  
S.U. Islam ◽  
Naqib Ullah ◽  
Chao Ying Zhou
Keyword(s):  
Numerical Analysis ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Numerical Results ◽  
Computational Domain ◽  
Blockage Ratio ◽  
Two Dimensional ◽  
Parallel Plates ◽  
Single Cylinder ◽  
Boltzmann Method

In this study the two-dimensional flow over a square cylinder placed in a parallel plates is simulated numerically by using lattice Boltzmann method (LBM) at low Reynolds numbers. Both the plates are obstructed by solid rectangular blocks of variable length. The fluid was allowed to flow in a parallel plates for Reynolds number (Re) from 75 to 150, and blockage ratio (g*) ranges from 1 to 3. The numerical investigation does not simply yield the predictable primary region of recirculating flow connected to the obstructions, it also shows supplementary regions of the flow downstream of the single cylinder placed in a computational domain. These supplementary separation zones were not already described in the research. The numerical analysis shows that the downstream flow of obstructions and single cylinder remained two dimensional for Re varied from75 to 150. Results available in previous research, are reported and compared with both of the available experimental and numerical results for code validation with single cylinder. Furthermore the effects of various Re and blockage ratio on the lift forces and drag coefficient is analyzed. Under these circumstances, good agreement between experimental and numerical results are obtained. The hydrodynamic forces of the cylinder are strongly influenced by the spacing ratios.

A Novel Approach to Model Thermo-Fluids of Gearbox Systems

2013 ◽  
Author(s):  
Miad Yazdani ◽  
Marios Soteriou ◽  
Barbara Botros ◽  
Hailing Wu ◽  
Joe Liou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Mechanics ◽  
Automobile Industry ◽  
Driving Forces ◽  
Fluid Model ◽  
Phase Interface ◽  
Computational Cost ◽  
Operating Conditions ◽  
Two Phase ◽  
Ansys Fluent

Gearboxes are integral machine components that determine the capability and reliability of many aerospace and automobile industry systems. Continuous demand for higher efficiency and reliability, increased load-carrying capacity and endurance life, smaller size, lower weight, lower noise and vibrations, prolonged service intervals and low costs are the main driving forces in the development of gear drives in the future. For many gearboxes, the thermo-fluids of the gas/oil/solid system determine the gearbox performance and its durability and life. However, there is a very limited predictive capability of the thermo-fluid characteristics of gearbox due, in large part, to its excessive complexity. In this paper, we present a coupled thermo-fluid model for the simulation of the two-phase flow along with the heat transfer within gearbox systems in a conjugate fashion. The primary challenge is the enormous separation of fluid-mechanics and heat-transfer time-scales which makes the conventional way of solving the coupled thermo-fluid system of equations computationally prohibitive. In contrast, the approximate approach developed in this study exploits this separation of scales to provide an accurate representation of the long-term, time dependent thermo-fluid state of the gearbox at a modest computational cost. The commercial package ANSYS FLUENT is used to solve URANS equations for fluid mechanics and VOF for the two-phase interface capturing, while the energy equation is modified through user-defined functions to solve for the temperature field inside the fluid and solid components. In addition, the heat generation raised by the meshing of the gears is provided by a separate model based on gear geometry and operating conditions. The approach is verified against a full-fidelity simulation for a simplified and accelerated gear system and is validated against experiments.

Lattice Boltzmann Simulation of Two-Phase Flow and Heat Transfer in a Rectangular Channel

2004 ◽  
Author(s):  
Peng Yuan ◽  
Laura Schaefer
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Phase Interface ◽  
Lattice Boltzmann Model ◽  
Phase Flow ◽  
Two Phase ◽  
Flow And Heat Transfer ◽  
Advection Diffusion Equation

The lattice Boltzmann method (LBM) is a kinetic approach, which assumes that a fluid consists of mesoscopic fluid particles with repeating collision and streaming patterns and is used to solve for the hydrodynamic phenomena of various systems In this work, we employ the LBM to investigate two-phase flow and heat transfer problems in a rectangular channel. First, the validity of the LBM is shown through some benchmark tests. Next, we use a single component multi-phase lattice Boltzmann model proposed by Shan and Chen to simulate two-phase flow in the channel. The two-phase interface is reproduced by interaction between different kinds of particles. The temperature field is simulated using the passive scalar approach, i.e. modeling the density field of an extra component, which evolves according to the advection-diffusion equation. Fluid-solid interaction, gravity, and the pressure gradient are also incorporated into the model. The dynamic behavior of the bubble under different conditions is investigated.

scholarly journals Lattice boltzmann simulation of boiling heat transfer in a shear flow

2020 ◽  
Vol 24 (Suppl. 1) ◽  
pp. 277-284
Author(s):  
Xiaopeng Shan ◽  
Geng Guan ◽  
Deming Nie
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Shear Flow ◽  
Lattice Boltzmann ◽  
Abnormal Behavior ◽  
Heated Plate ◽  
Two Phase ◽  
Average Heat ◽  
Lattice Boltzmann Simulation ◽  
Flow Features

In this work a two-phase lattice Boltzmann method was used to numerically study the behavior of liquid-vapor phase change induced by a heated plate under the action of shearing. The effects of the action of shearing on the bubble growth and departure were investigated in terms of the flow features, the average heat flux and the bubble releasing period. It is shown that the shear flow significantly enhances the heat transfer of the system in two respects: increasing the average heat flux and decreasing the bubble releasing period. The effects of the intensity of the shear flow and the gravity force on the bubble releasing period were examined as well. The most striking finding is that there exists a sudden jump in the period at a critical shear intensity of the flow. The reason behind this abnormal behavior is that the residual part of bubble is nearly condensed after the bulk of bubble departs from the heated plate.

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