AN ELASTIC-COLLISION SCHEME FOR LATTICE BOLTZMANN METHODS

2001 ◽  
Vol 12 (03) ◽  
pp. 387-401 ◽  
Author(s):  
J. G. ZHOU
Keyword(s):  
Experimental Data ◽  
Lattice Boltzmann ◽  
Elastic Collision ◽  
Complex Geometries ◽  
Slip Boundary Conditions ◽  
Lattice Boltzmann Methods ◽  
Slip Boundary ◽  
Arbitrary Complex ◽  
Bounce Back ◽  
Good Agreement

An elastic-collision scheme is developed to achieve slip and semi-slip boundary conditions for lattice Boltzmann methods. Like the bounce-back scheme, the proposed scheme is efficient, robust and generally suitable for flows in arbitrary complex geometries. It involves an equivalent level of computation effort to the bounce-back scheme. The new scheme is verified by predicting wind-driven circulating flows in a dish-shaped basin and a flow in a strongly bent channel, showing good agreement with analytical solutions and experimental data. The capability of the scheme for simulating flows through multiple bodies has also been demonstrated.

scholarly journals Numerical Simulations of Flows in a Cerebral Aneurysm Using the Lattice Boltzmann Method with the Half-Way and Interpolated Bounce-Back Schemes

Fluids ◽  
2021 ◽  
Vol 6 (10) ◽  
pp. 338
Author(s):  
Susumu Osaki ◽  
Kosuke Hayashi ◽  
Hidehito Kimura ◽  
Takeshi Seta ◽  
Takashi Sasayama ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cerebral Aneurysm ◽  
Lattice Boltzmann ◽  
Flow Simulation ◽  
Slip Boundary Condition ◽  
Slip Boundary ◽  
Lattice Boltzmann Simulations ◽  
Complex Boundary ◽  
Boltzmann Method ◽  
Bounce Back

Lattice Boltzmann simulations and a velocity measurement of flows in a cerebral aneurysm reconstructed from MRA (magnetic resonance angiography) images of an actual aneurysm were carried out and the numerical results obtained using the bounce-back schemes were compared with the experimental data to discuss the effects of the numerical treatment of the no-slip boundary condition of the complex boundary shape of the aneurysm on the predictions. The conclusions obtained are as follows: (1) measured data of the velocity in the aneurysm model useful for validation of numerical methods were obtained, (2) the numerical stability of the quadratic interpolated bounce-back scheme (QBB) in the flow simulation of the cerebral aneurysm is lower than those of the half-way bounce-back (HBB) and the linearly interpolated bounce-back (LBB) schemes, (3) the flow structures predicted using HBB and LBB are comparable and agree well with the experimental data, and (4) the fluctuations of the wall shear stress (WSS), i.e., the oscillatory shear index (OSI), can be well predicted even with the jaggy wall representation of HBB, whereas the magnitude of WSS predicted with HBB tends to be smaller than that with LBB.

Examination of the Slip Boundary Condition by µ-PIV and Lattice Boltzmann Simulations

2002 ◽  
Author(s):  
Derek C. Tretheway ◽  
Luoding Zhu ◽  
Linda Petzold ◽  
Carl D. Meinhart
Keyword(s):  
Boundary Condition ◽  
Shear Rate ◽  
Channel Flow ◽  
Lattice Boltzmann ◽  
Slip Velocity ◽  
Slip Length ◽  
Slip Boundary Condition ◽  
Slip Boundary ◽  
Lattice Boltzmann Simulations ◽  
Bounce Back

This work examines the slip boundary condition by Lattice Boltzmann simulations, addresses the validity of the Navier’s hypothesis that the slip velocity is proportional to the shear rate and compares the Lattice Boltzmann simulations to the experimental results of Tretheway and Meinhart (Phys. of Fluids, 14, L9–L12). The numerical simulation models the boundary condition as the probability, P, of a particle to bounce-back relative to the probability of specular reflection, 1−P. For channel flow, the numerically calculated velocity profiles are consistent with the experimental profiles for both the no-slip and slip cases. No-slip is obtained for a probability of 100% bounce-back, while a probability of 0.03 is required to generate a slip length and slip velocity consistent with the experimental results of Tretheway and Meinhart for a hydrophobic surface. The simulations indicate that for microchannel flow the slip length is nearly constant along the channel walls, while the slip velocity varies with wall position as a results of variations in shear rate. Thus, the resulting velocity profile in a channel flow is more complex than a simple combination of the no-slip solution and slip velocity as is the case for flow between two infinite parallel plates.

Liquid Transport Properties in Sub-Micron Channel Flows

2001 ◽  
Author(s):  
K. Johan A. Westin ◽  
Kenneth S. Breuer ◽  
Chang-Hwan Choi ◽  
Peter Huang ◽  
Zhiqiang Cao ◽  
...  
Keyword(s):  
Flow Rate ◽  
Low Flow ◽  
Slip Boundary Conditions ◽  
Liquid Transport ◽  
Flow Rates ◽  
Slip Boundary ◽  
Laminar Channel Flow ◽  
Flow Through ◽  
Set Up ◽  
Good Agreement

Abstract An experimental set-up for pressure driven liquid flow through microchannels have been designed and tested. The flow rate is determined by tracking the free liquid surface in a precision bore hole using a laser distance meter. Measurements of the flow rate through silicon microchannels with a height of less than 0.9 μm show good results for Newtonian fluids (silicon oil, ethanol) at flow rates as low as 0.2 nl/s. The experimental results are also in very good agreement with predictions based on laminar channel flow using no-slip boundary conditions, indicating that standard macroscopic assumptions are still valid for these fluids under these conditions. However, experiments with aqueous solutions show anomalies in the form of unexpectedly low flow rates and time dependent variations. Possible explanations to these observations are discussed.

Effect of Wall Conduction on the Stability of a Fluid in a Rectangular Region Heated from Below

1972 ◽  
Vol 94 (4) ◽  
pp. 446-452 ◽  
Author(s):  
Ivan Catton
Keyword(s):  
Lateral Wall ◽  
Rectangular Region ◽  
Slip Boundary Conditions ◽  
Slip Boundary ◽  
Aspect Ratios ◽  
Usual Manner ◽  
Vertical Walls ◽  
The Stability ◽  
The Galerkin Method ◽  
Good Agreement

The initiation of natural convection in a fluid confined above and below by rigid, perfectly conducting surfaces and laterally by vertical walls of arbitrary thermal conductivity which form a rectangle is examined. The linearized perturbation equations are obtained in the usual manner and reduced to an eigenvalue problem. The Rayleigh number is the eigenvalue and is a function of the lateral-wall conductance and horizontal plan form (aspect ratios). The problem associated with satisfying the no-slip boundary conditions on all surfaces is surmounted by using the Galerkin method. Results are compared with experiments and shown to be in good agreement.

THE OPENLB PROJECT: AN OPEN SOURCE AND OBJECT ORIENTED IMPLEMENTATION OF LATTICE BOLTZMANN METHODS

2007 ◽  
Vol 18 (04) ◽  
pp. 627-634 ◽  
Author(s):  
VINCENT HEUVELINE ◽  
JONAS LATT
Keyword(s):  
Open Source ◽  
Data Structures ◽  
Lattice Boltzmann ◽  
Object Oriented ◽  
Parallel Program ◽  
Underlying Structure ◽  
Complex Geometries ◽  
Lattice Boltzmann Methods ◽  
Development Tool ◽  
Lattice Boltzmann Models

The OpenLB project aims at setting up an open source implementation of lattice Boltzmann methods in an object oriented framework. The code, which is written in C ++, is intended to be used both by application programmers and by developers who may add their own particular dynamics. It supports advanced data structures that take into account complex geometries and parallel program executions. The programming concepts rely strongly on dynamic genericity through the use of object oriented interfaces as well as static genericity by means of templates. This design allows a straightforward and intuitive implementation of lattice Boltzmann models with almost no loss of efficiency. The aim of this paper is to introduce the OpenLB project and to depict the underlying structure leading to a powerful development tool for lattice Boltzmann methods.

Numerical Investigation of an Extended Propeller Viscosimeter by Means of Lattice Boltzmann Methods

2013 ◽  
Author(s):  
Daniel Conrad ◽  
Andreas Schneider ◽  
Martin Böhle
Keyword(s):  
Lattice Boltzmann ◽  
Reference Frames ◽  
Computational Fluid Mechanics ◽  
Complex Geometries ◽  
Grid Refinement ◽  
Flow Properties ◽  
Lattice Boltzmann Methods ◽  
Alternative Approach ◽  
Newtonian Case ◽  
Different Levels

For the design of mixing and agitation facilities in process engineering it is of central importance to appraise the correct viscosity of fluids. This can be a challenging task when non-Newtonian and/or non-homogeneous fluids need to be processed. Since it is not always possible to analyze them in the classical ways, an propeller viscosimeter approach on the basis of the Rieger-Novak-Method is used. In recent years the Lattice Boltzmann Methods (LBM) are established as an alternative approach to classical computational fluid mechanics methods. The utilization of Cartesian grids avoids the need to discretize with boundary conform meshes. This makes the LBM suitable for complex geometries like a propeller in this case. Numerical simulations were carried out using a 3D in-house Lattice Boltzmann code called SAM-Lattice with our latest extension to non-Newtonian flow. We use a truncated form of the power-law approximation to accommodate the varying flow properties in non-Newtonian simulations, where the effective viscosity is a function of the shear rate. SAM-Lattice comprises the LBM solver and a highly automated grid generator for arbitrarily complex geometries. The code is capable of multi-domain grid refinement as well as multi reference frames and rotational boundaries. The post processing is done using an extension of the open source visualization tool Paraview. We compare results of experiments and LBM simulations for the Newtonian case (Glucose) to validate our Lattice Boltzmann solver. A study of the non-Newtonian, shear thinning case (Xanthan) is conducted to validate the generalized Newtonian model. The propeller viscosimeter is currently under development as a standalone solution for viscosity measurement. For calibration purposes the Metzner-Otto-constant of the propeller device has to be determined. While the constant is valid for the laminar region the numerical results for the agitator characteristics are presented. Different levels of grid refinement are tested to assure independence of the lattice resolutions.

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