scholarly journals Transverse harmonic oscillations of laminae in viscous fluids: a lattice Boltzmann study

2011 ◽  
Vol 369 (1945) ◽  
pp. 2456-2466 ◽  
Author(s):  
Giacomo Falcucci ◽  
Matteo Aureli ◽  
Stefano Ubertini ◽  
Maurizio Porfiri
Keyword(s):  
Lattice Boltzmann ◽  
Small Amplitude ◽  
Collision Operator ◽  
Added Mass ◽  
Viscous Fluids ◽  
Harmonic Oscillations ◽  
Hydrodynamic Damping ◽  
Theoretical Predictions ◽  
Boltzmann Method ◽  
Hydrodynamic Function

In this paper, we use the lattice Boltzmann method with the Bhatnagar–Gross–Krook linear collision operator to study the flow physics induced by a rigid lamina undergoing moderately large harmonic oscillations in a viscous fluid. We propose a refill procedure for the hydrodynamic quantities in the lattice sites that are in the vicinity of the oscillating lamina. The numerically estimated flow field is used to compute the complex hydrodynamic function that describes the added mass and hydrodynamic damping experienced by the lamina. Results of the numerical simulations are validated against theoretical predictions for small amplitude vibrations and experimental and numerical findings for moderately large oscillations.

SIMULATION OF AN AXISYMMETRIC RISING BUBBLE BY A MULTIPLE RELAXATION TIME LATTICE BOLTZMANN METHOD

2009 ◽  
Vol 23 (24) ◽  
pp. 4907-4932 ◽  
Author(s):  
ABBAS FAKHARI ◽  
MOHAMMAD HASSAN RAHIMIAN
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Rise Velocity ◽  
Rising Bubble ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Multiple Relaxation Time ◽  
Bubble Rising ◽  
Boltzmann Method

In this paper, the lattice Boltzmann method is employed to simulate buoyancy-driven motion of a single bubble. First, an axisymmetric bubble motion under buoyancy force in an enclosed duct is investigated for some range of Eötvös number and a wide range of Archimedes and Morton numbers. Numerical results are compared with experimental data and theoretical predictions, and satisfactory agreement is shown. It is seen that increase of Eötvös or Archimedes number increases the rate of deformation of the bubble. At a high enough Archimedes value and low Morton numbers breakup of the bubble is observed. Then, a bubble rising and finally bursting at a free surface is simulated. It is seen that at higher Archimedes numbers the rise velocity of the bubble is greater and the center of the free interface rises further. On the other hand, at high Eötvös values the bubble deforms more and becomes more stretched in the radial direction, which in turn results in lower rise velocity and, hence, lower elevations for the center of the free surface.

scholarly journals A unified lattice Boltzmann model and application to multiphase flows

2021 ◽  
Vol 379 (2208) ◽  
pp. 20200397 ◽  
Author(s):  
Kai H. Luo ◽  
Linlin Fei ◽  
Geng Wang
Keyword(s):  
Lattice Boltzmann ◽  
Model Comparison ◽  
Collision Operator ◽  
Central Moment ◽  
Lattice Boltzmann Model ◽  
Dynamics Simulation ◽  
Flow Problems ◽  
Multiple Relaxation Time ◽  
Boltzmann Method ◽  
Boltzmann Model

In this work, we develop a unified lattice Boltzmann model (ULBM) framework that can seamlessly integrate the widely used lattice Boltzmann collision operators, including the Bhatnagar–Gross–Krook or single-relation-time, multiple-relaxation-time, central-moment or cascaded lattice Boltzmann method and multiple entropic operators (KBC). Such a framework clarifies the relations among the existing collision operators and greatly facilitates model comparison and development as well as coding. Importantly, any LB model or treatment constructed for a specific collision operator could be easily adopted by other operators. We demonstrate the flexibility and power of the ULBM framework through three multiphase flow problems: the rheology of an emulsion, splashing of a droplet on a liquid film and dynamics of pool boiling. Further exploration of ULBM for a wide variety of phenomena would be both realistic and beneficial, making the LBM more accessible to non-specialists. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

scholarly journals Lattice Boltzmann Method for Two-Dimensional Unsteady Incompressible Flow

2016 ◽  
Vol 12 (2) ◽  
pp. 122-127
Author(s):  
Juraj Mužík
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Collision Operator ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equation ◽  
Driven Cavity ◽  
Boltzmann Method ◽  
Incompressible Navier Stokes Equation

Abstract A Lattice Boltzmann method is used to analyse incompressible fluid flow in a two-dimensional cavity and flow in the channel past cylindrical obstacle. The method solves the Boltzmann’s transport equation using simple computational grid - lattice. With the proper choice of the collision operator, the Boltzmann’s equation can be converted into incompressible Navier-Stokes equation. Lid-driven cavity benchmark case for various Reynolds numbers and flow past cylinder is presented in the article. The method produces stable solutions with results comparable to those in literature and is very easy to implement.

Lattice Boltzmann Simulation of Nucleation

2003 ◽  
Author(s):  
Takeshi Seta ◽  
Kenichi Okui ◽  
Eisyun Takegoshi
Keyword(s):  
Lattice Boltzmann ◽  
Lattice Boltzmann Model ◽  
Two Phase Flows ◽  
Two Phase ◽  
Lattice Boltzmann Simulation ◽  
Expansion Procedure ◽  
Theoretical Predictions ◽  
Boltzmann Method ◽  
Boltzmann Model ◽  
Pseudo Potential

We propose a lattice Boltzmann model capable of simulating nucleation. This LBM modifies a pseudo-potential so that it recovers a full set of hydrodynamic equations for two-phase flows based on the van der Waals-Cahn-Hilliard free energy theory through the Chapman-Enskog expansion procedure. Numerical measurements of thermal conductivity and of surface tension agree well with theoretical predictions. Simulations of phase transition, nucleation, pool boiling are carried out. They demonstrate that the model is applicable to two-phase flows with thermal effects. Using finite difference Lattice Boltzmann method ensures numerical stability of the scheme.

Numerical Simulations of Flows in Cerebral Aneurysms Using the Lattice Boltzmann Method

2020 ◽  
Author(s):  
Susumu Osaki ◽  
Kosuke Hayashi ◽  
Hidehito Kimura ◽  
Eiji Kohmura ◽  
Akio Tomiyama
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Flow Characteristics ◽  
Cerebral Aneurysms ◽  
Collision Operator ◽  
Velocity Model ◽  
Outflow Boundary Condition ◽  
Aneurysm Wall ◽  
Outflow Boundary ◽  
Boltzmann Method

Abstract The lattice Boltzmann method (LBM) is used to simulate blood flows in cerebral aneurysms and the effects of the outflow boundary condition on predictions are studied. The LBM utilizes the D3Q19 discrete velocity model, the multiple-relaxation time collision operator (MRT), and the interpolated bounce-back rule to treat complex aneurysm shapes. Flow characteristics in regions of a large fluctuation in the wall shear stress (WSS) were then investigated using the LBM to understand the relation between the flow structure and the aneurysm wall remodeling. As a result the following conclusions were obtained under the present range of the numerical condition: (1) even with significant changes in the flow rate distributions at outflow boundaries, the WSS in an aneurysm is not much affected if the boundaries are far from the aneurysm, and (2) the geometry of an aneurysm and the main artery largely affects the formation of large WSS fluctuation regions, which may thickens the aneurysm wall due to inflammation-induced wall remodeling.

LATTICE BOLTZMANN METHOD FOR TWO-PHASE FLOWS

2003 ◽  
Vol 17 (01n02) ◽  
pp. 169-172 ◽  
Author(s):  
TAKESHI SETA ◽  
KOJI KONO ◽  
SHIYI CHEN
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Fluid Flows ◽  
Numerical Verification ◽  
Two Phase ◽  
Fundamental Properties ◽  
Thermal Fluids ◽  
Theoretical Predictions ◽  
Bubble Rising ◽  
Boltzmann Method

A lattice Boltzmann method (LBM) for two-phase nonideal fluid flows is proposed based on a particle velocity-dependent forcing scheme. The resulting macroscopic dynamics via the Chapman-Enskog expansion recover the full set of thermohydrodynamic equations for nonideal fluids. Numerical verification of fundamental properties of thermal fluids, including thermal conductivity and surface tension, agrees well with theoretical predictions. Direct numerical simulations of two-phase phenomena, including phase-transition, bubble deformation and droplet falling and bubble rising under gravity are carried out, demonstrating the applicability of the model.

Analysis of the Fluid Motion Induced by a Vibrating Lamina Through Free Surface-Lattice Boltzmann Coupled Method

2018 ◽  
Author(s):  
Daniele Chiappini ◽  
Giovanni Di Ilio ◽  
Gino Bella
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann ◽  
Parametric Analysis ◽  
Numerical Study ◽  
Fluid Motion ◽  
Added Mass ◽  
Finite Amplitude ◽  
Viscous Damping ◽  
Integrated Method ◽  
Hydrodynamic Function

In this work, we perform a numerical study on the flow induced by the motion of a rigid cantilever beam undergoing finite amplitude oscillations, in a viscous fluid, under a free surface. To this aim, we use a lattice Boltzmann volume of fluid (LB-VOF) integrated method, which includes the tracking of the fluid surface. The adopted approach couples the simplicity of the LB method with the possibility to track the free surface by means of a VOF strategy. Through a parametric analysis, we study the effects related to the depth of submergence, for several values of the oscillation frequency and amplitude. Results are provided in terms of a complex hydrodynamic function, whose real and imaginary parts are the added mass and the viscous damping, respectively, acting on the lamina. Validation of the results is carried out by comparing the solution, for the limit case of lamina submerged in an infinite fluid, with those from available literature studies. We find that the presence of the free surface strongly influences the flow physics around the lamina, especially at low values of the depth of submergence. In facts, when the lamina approaches to the free surface, the fluid waves, generated by the motion of the lamina, interact with the oscillating body itself, giving rise to additional effects, which we quantify in terms of added mass and viscous damping.

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