SIMULATION OF STENOSIS GROWTH IN THE CAROTID ARTERY BY LATTICE BOLTZMANN METHOD

2014 ◽  
Vol 14 (02) ◽  
pp. 1450016 ◽  
Author(s):  
H. KARIMPOUR ◽  
E. JAVDAN
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Systemic Disease ◽  
Shear Stresses ◽  
Computational Domain ◽  
Lattice Method ◽  
Highly Oscillatory ◽  
Wall Shear ◽  
Boltzmann Method

Atherosclerosis, as the leading cause of mortality, is usually regarded as a systemic disease and several well-identified risk factors have been implicated in its pathogenesis. Low or highly oscillatory wall shear stress has mainly been linked to the development of atherosclerosis. Conditions under which human blood can be considered Newtonian for the purpose of arterial flow modeling are investigated with emphasis on near wall shear stresses. The Lattice Boltzmann method is implemented in parallel for both Newtonian and non-Newtonian models of blood and then examined in the context of steady and oscillatory flows. As the lattice method permits to adjust the morphology of the computational domain during the solving process, the artery walls are reshaped in a recursive manner by the progressive accumulation of deposits according to the conventional OSI criterion. Regions subjected to partial obstructions identified qualitatively well with those susceptible to atherosclerosis in the in vivo sample, thereby approving this criterion by verifying its accumulative effect. The present work demonstrates the suitability of LB method for studying flows across geometries that transform due to atherosclerotic progression and permits to explain the trend of deposit distribution across time.

A Meshfree-Based Lattice Boltzmann Approach for Simulation of Fluid Flows Within Complex Geometries

2018 ◽  
pp. 188-222 ◽  
Author(s):  
Sonam Tanwar
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Moving Boundary ◽  
Fluid Flows ◽  
Computational Domain ◽  
Time Step ◽  
Boundary Problems ◽  
Complex Process ◽  
Element Free ◽  
Boltzmann Method

This chapter develops a meshless formulation of lattice Boltzmann method for simulation of fluid flows within complex and irregular geometries. The meshless feature of proposed technique will improve the accuracy of standard lattice Boltzmann method within complicated fluid domains. Discretization of such domains itself may introduce significant numerical errors into the solution. Specifically, in phase transition or moving boundary problems, discretization of the domain is a time-consuming and complex process. In these problems, at each time step, the computational domain may change its shape and need to be re-meshed accordingly for the purpose of accuracy and stability of the solution. The author proposes to combine lattice Boltzmann method with a Galerkin meshfree technique popularly known as element-free Galerkin method in this chapter to remove the difficulties associated with traditional grid-based methods.

Direct Numerical Simulation of an Open-Cell Metallic Foam through Lattice Boltzmann Method

2015 ◽  
Vol 18 (3) ◽  
pp. 707-722 ◽  
Author(s):  
Daniele Chiappini ◽  
Gino Bella ◽  
Alessio Festuccia ◽  
Alessandro Simoncini
Keyword(s):  
Numerical Simulation ◽  
Porous Media ◽  
Direct Numerical Simulation ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Media Analysis ◽  
Metallic Foam ◽  
Computational Domain ◽  
Open Cell ◽  
Boltzmann Method

AbstractIn this paper Lattice Boltzmann Method (LBM) has been used in order to perform Direct Numerical Simulation (DNS) for porous media analysis. Among the different configurations of porous media, open cell metallic foams are gaining a key role for a large number of applications, like heat exchangers for high performance cars or aeronautic components as well. Their structure allows improving heat transfer process with fruitful advantages for packaging issues and size reduction. In order to better understand metallic foam capabilities, a random sphere generation code has been implemented and fluid-dynamic simulations have been carried out by means of a kinetic approach. After having defined a computational domain the Reynolds number influence has been studied with the aim of characterizing both pressure drop and friction factor throughout a finite foam volume. In order to validate the proposed model, a comparison analysis with experimental data has been carried out too.

Modeling groundwater flow by lattice Boltzmann method in curvilinear coordinates

2015 ◽  
Vol 26 (02) ◽  
pp. 1550013 ◽  
Author(s):  
Ljubomir Budinski ◽  
Julius Fabian ◽  
Matija Stipic
Keyword(s):  
Groundwater Flow ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Complex Geometry ◽  
Poisson’S Equation ◽  
Curvilinear Coordinates ◽  
Computational Domain ◽  
Poisson's Equation ◽  
Equilibrium Function ◽  
Boltzmann Method

In order to promote the use of the lattice Boltzmann method (LBM) for the simulation of isotropic groundwater flow in a confined aquifer with arbitrary geometry, Poisson's equation was transformed into a curvilinear coordinate system. With the metric function between the physical and the computational domain established, Poisson's equation written in Cartesian coordinates was transformed in curvilinear coordinates. Following, the appropriate equilibrium function for the D2Q9 square lattice has been defined. The resulting curvilinear formulation of the LBM for groundwater flow is capable of modeling flow in domains of complex geometry with the opportunity of local refining/coarsening of the computational mesh corresponding to the complexity of the flow pattern and the required accuracy. Since the proposed form of the LBM uses the transformed equation of flow implemented in the equilibrium function, finding a solution does not require supplementary procedures along the curvilinear boundaries, nor in the zones requiring mesh density adjustments. Thus, the basic concept of the LBM is completely maintained. The improvement of the proposed LBM over the previously published classical methods is completely verified by three examples with analytical solutions. The results demonstrate the advantages of the proposed curvilinear LBM in modeling groundwater flow in complex flow domains.

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.

IMMERSED BOUNDARY METHOD BASED LATTICE BOLTZMANN METHOD TO SIMULATE 2D AND 3D COMPLEX GEOMETRY FLOWS

2007 ◽  
Vol 18 (04) ◽  
pp. 585-594 ◽  
Author(s):  
DI-JIA CHEN ◽  
KUN-HAO LIN ◽  
CHAO-AN LIN
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Complex Geometry ◽  
Delta Function ◽  
Immersed Boundary ◽  
Computational Domain ◽  
Boltzmann Method ◽  
2D And 3D ◽  
Benchmark Solutions ◽  
Eulerian Grid

In this paper, the lattice Boltzmann method is combined with the immersed boundary technique to simulate complex geometry flows. The complex geometry is represented by Lagrangian markers and forces are exerted at the Lagrangian markers in order to satisfy the prescribed velocity of the boundary. This force at the Lagrangian markers is then distributed to the Eulerian grid by a well-chosen discretized delta function. With the known force field in the Eulerian grid to mimic the boundary, the lattice Boltzmann method is used to compute the flow field where the complex geometry is immersed inside the Cartesian computational domain. Numerical experiments show that the second-order accuracy of the adopted numerical scheme is degraded to 1.8 order. The proposed method is examined by computing decaying vortex, lid driven cavity flow and 2D and 3D flows over asymmetrically placed cylinder. All the numerical results are compatible with the benchmark solutions.

Aeroacoustic Simulations Using Compressible Lattice Boltzmann Method

2016 ◽  
Vol 8 (5) ◽  
pp. 795-809 ◽  
Author(s):  
Kai Li ◽  
Chengwen Zhong
Keyword(s):  
Numerical Simulation ◽  
Lattice Boltzmann Method ◽  
Vortex Shedding ◽  
Lattice Boltzmann ◽  
Buffer Zone ◽  
Computational Domain ◽  
Absorbing Boundary ◽  
Naca0012 Airfoil ◽  
Characteristic Features ◽  
Boltzmann Method

AbstractThis paper presents a lattice Boltzmann (LB) method based study aimed at numerical simulation of aeroacoustic phenomenon in flows around a symmetric obstacle. To simulate the compressible flow accurately, a potential energy double-distribution-function (DDF) lattice Boltzmann method is used over the entire computational domain from the near to far fields. The buffer zone and absorbing boundary condition is employed to eliminate the non-physical reflecting. Through the direct numerical simulation, the flow around a circular cylinder atRe=150,M=0.2 and the flow around a NACA0012 airfoil atRe=10000,M=0.8,α=0° are investigated. The generation and propagation of the sound produced by the vortex shedding are reappeared clearly. The obtained results increase our understanding of the characteristic features of the aeroacoustic sound.

Two Phase Flow Simulation With Lattice Boltzmann Method: Application to Wave Breaking

2013 ◽  
Author(s):  
Amir Banari ◽  
Stephan T. Grilli ◽  
Christian F. Janssen
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Wave Breaking ◽  
Fluid Pressure ◽  
High Density ◽  
Three Dimensions ◽  
Breaking Wave ◽  
Computational Domain ◽  
Density Ratios ◽  
Boltzmann Method

A new Lattice Boltzmann method (LBM) is developed to efficiently simulate multiphase flows with high density ratios, in order to study complex air-sea interaction problems, such as wind wave breaking and related sea-spray generation. In this method, which builds and improves on the method proposed earlier by [1], the motion of (diffusive) interfaces between fluids is modeled by solving the convective Cahn-Hilliard equation with the LBM. As in the latter work, we eliminate instabilities resulting from high density ratios by solving an additional Poisson equation for the fluid pressure. The resulting numerical scheme is computationally demanding since this equation must be solved over the entire computational domain, which motivates implementing the method on the massively parallel environment offered by General Purpose Graphical Processing Units (GPGPU), via the nVIDIA CUDA framework. In this paper, we present the equations and numerical methods for the method and the initial validation of the resulting multiphase-LBM for standard benchmark problems such as Poiseuille flow, a rising bubble, and Rayleigh-Taylor instability for two-fluid systems. A good agreement with the reference solutions is achieved in all cases. Finally, the method is applied to simulating an ocean breaking wave in a space periodic domain. In all the presented applications, it is observed that the GPGPU implementation leads to speed-ups of about two orders of magnitude in comparison to a single-core CPU implementation. Although the method is only currently implemented in a two-dimensional (2D) framework, its extension to three-dimensions (3D) should be straightforward, but the need for the efficient GPGPU implementation will become even more drastic in 3D.

Modelling wall shear stress in small arteries using the Lattice Boltzmann method: influence of the endothelial wall profile

2011 ◽  
Vol 33 (7) ◽  
pp. 832-839 ◽  
Author(s):  
Giuseppe Pontrelli ◽  
Carola S. König ◽  
Ian Halliday ◽  
Timothy J. Spencer ◽  
Michael W. Collins ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Small Arteries ◽  
Wall Shear ◽  
Wall Profile ◽  
Boltzmann Method
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