scholarly journals Large-scaled simulation on the coherent vortex evolution of a jet in a cross-flow based on lattice Boltzmann method

2015 ◽  
Vol 19 (3) ◽  
pp. 977-988 ◽  
Author(s):  
Yanqin Shangguan ◽  
Xian Wang ◽  
Yueming Li
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Hairpin Vortex ◽  
Graphic Processing Units ◽  
Computational Performance ◽  
Good Ability ◽  
Secondary Vortices ◽  
Boltzmann Method

Large eddy simulation (LES) is performed on a jet issued normally into a cross-flow using lattice Boltzmann method (LBM) and multiple graphic processing units (multi-GPUs) to study the flow characteristics of jets in cross-flow (JICF). The simulation with 8 1.50?10 grids is fulfilled with 6 K20M GPUs. With large-scaled simulation, the secondary and tertiary vortices are captured. The features of the secondary vortices and the tertiary vortices reveal that they have a great impact on the mixing between jet flow and cross-flow. The qualitative and quantitative results also indicate that the evolution mechanism of vortices is not constant, but varies with different situations. The hairpin vortex under attached jet regime originates from the boundary layer vortex of cross-flow. While, the origin of hairpin vortex in detached jet is the jet shear-layer vortex. The mean velocities imply the good ability of LBM to simulate JICF and the large loss of jet momentum in detached jet caused by the strong penetration. Besides, in our computation, a high computational performance of 1083.5 MLUPS is achieved.

Numerical Simulation for Flow over Two Circular Cylinders in Micro Channel with Lattice Boltzmann Method

2014 ◽  
Vol 670-671 ◽  
pp. 747-750
Author(s):  
Zhi Jun Gong ◽  
Jiao Yang ◽  
Wen Fei Wu
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Recirculation Zone ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Micro Channel ◽  
Zone Length ◽  
Spacing Ratio ◽  
Boltzmann Method

For indepth study on flow characteristics for fluid bypass obstacles in micro-channel, the Lattice Boltzmann Method (LBM) was used to simulate fluid flow over two circular cylinders in side-by-side arrangement of a micro-channel. The velocity distribution and recirculation zone length under different Reynolds numbers (Re = 0~100) and different spacing ratio (H/D= 0~2.0) were obtained. The results show that the pattern of flow and the size of recirculation zone in the micro-channel depend on the combined effect of Re and H/D.

Flow Characteristics of Rarified Gases in Micro-Grooved Channels by the Lattice-Boltzmann Method

2008 ◽  
Author(s):  
Amador M. Guzma´n ◽  
Andre´s J. Di´az ◽  
Luis E. Sanhueza ◽  
Rodrigo A. Escobar
Keyword(s):  
Numerical Simulations ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Pressure Ratio ◽  
Plane Channel ◽  
Flow Characteristics ◽  
Numerical Results ◽  
Knudsen Numbers ◽  
Channel Configuration ◽  
Boltzmann Method

The flow characteristics of a rarified gas have been investigated in microgrooved channels. The governing Boltzmann Transport Equation (BTE) is solved by the Lattice-Boltzmann method (LBM) for the Knudsen number range of 0.01–0.1. First, the compressibility and rarified effects are investigated in a plane channel by performing numerical simulations for different Knudsen numbers, pressure ratio and accommodation coefficients with the objective of validating the computational code used in this investigation and determining the transition characteristics from the macro to microscale. The numerical predictions are compared to existing analytical and numerical results. Then, numerical simulations are performed for microgrooved channels for the Knudsen numbers range of [0.01–0.1]. Different meshes are used for preserving numerical stabilities and obtaining accurate enough numerical results. For the microgrooved channel configuration, the fluid characteristics are determined in terms of pressure ratio and Knudsen numbers. The numerical results are compared to existing analytical predictions and numerical results obtained from plane channel and one cavity simulations.

scholarly journals Direct Numerical Simulation and Large Eddy Simulation on a Turbulent Wall-Bounded Flow Using Lattice Boltzmann Method and Multiple GPUs

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Xian Wang ◽  
Yanqin Shangguan ◽  
Naoyuki Onodera ◽  
Hiromichi Kobayashi ◽  
Takayuki Aoki
Keyword(s):  
Numerical Simulation ◽  
Large Eddy Simulation ◽  
Direct Numerical Simulation ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Graphic Processing Units ◽  
Multiple Gpus ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Boltzmann Method

Direct numerical simulation (DNS) and large eddy simulation (LES) were performed on the wall-bounded flow atReτ=180using lattice Boltzmann method (LBM) and multiple GPUs (Graphic Processing Units). In the DNS, 8 K20M GPUs were adopted. The maximum number of meshes is6.7×107, which results in the nondimensional mesh size ofΔ+=1.41for the whole solution domain. It took 24 hours for GPU-LBM solver to simulate3×106LBM steps. The aspect ratio of resolution domain was tested to obtain accurate results for DNS. As a result, both the mean velocity and turbulent variables, such as Reynolds stress and velocity fluctuations, perfectly agree with the results of Kim et al. (1987) when the aspect ratios in streamwise and spanwise directions are 8 and 2, respectively. As for the LES, the local grid refinement technique was tested and then used. Using1.76×106grids and Smagorinsky constant(Cs)=0.13, good results were obtained. The ability and validity of LBM on simulating turbulent flow were verified.

An Improved Lattice Boltzmann Method for Steady Fluid Flows

2004 ◽  
Author(s):  
Aditya C. Velivelli ◽  
Kenneth M. Bryden
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Finite Difference Methods ◽  
Nonlinear Partial Differential Equation ◽  
Step Size ◽  
Time Step ◽  
Time Step Size ◽  
Flow Problems ◽  
Computational Performance ◽  
Boltzmann Method

The use of the lattice Boltzmann method in computational fluid dynamics has been steadily increasing. The highly local nature of lattice Boltzmann computations have allowed for easy cache optimization and parallelization. This bestows the lattice Boltzmann method with considerable superiority in computational performance over traditional finite difference methods for solving unsteady flow problems. When solving steady flow problems, the explicit nature of the lattice Boltzmann discretization limits the time step size. The time step size is limited by the Courant-Friedrichs-Lewy (CFL) condition and local gradients in the solution, the latter limitation being more extreme. This paper describes a novel explicit discretization for the lattice Boltzmann method that can perform simulations with larger time step sizes. The new algorithm is applid to the steady Burger’s equation, uux = μ(uxx + uyy), which is a nonlinear partial differential equation containing both convection and diffusion terms. A comparison between the original lattice Boltzmann method and the new algorithm is performed with regard to time for computation and accuracy.

Wake Interaction Using Lattice Boltzmann Method

2018 ◽  
pp. 223-261
Author(s):  
K. Karthik Selva Kumar ◽  
L. A. Kumaraswamidhas
Keyword(s):  
Fluid Flow ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Computational Simulation ◽  
Fluid Structure Interaction ◽  
Flow Characteristics ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Fluid Flow Characteristics ◽  
Boltzmann Method

In this chapter, a brief discussion about the application of lattice Boltzmann method on complex flow characteristics over circular structures is presented. A two-dimensional computational simulation is performed to study the fluid flow characteristics by employing the lattice Boltzmann method (LBM) with respect to Bhatnagar-Gross-Krook (BGK) collision model to simulate the interaction of fluid flow over the circular cylinders at different spacing conditions. From the results, it is observed that there is no significant interaction between the wakes for the transverse spacing's ratio higher than six times the cylinder diameter. For smaller transverse spacing ratios, the fluid flow regimes were recognized with presence of vortices. Apart from that, the drag coefficient signals are revealed as chaotic, quasi-periodic, and synchronized regimes, which were observed from the results of vortex shedding frequencies and fluid structure interaction frequencies. The strength of the latter frequency depends on spacing between the cylinders; in addition, the frequency observed from the fluid structure interaction is also associated with respect to the change in narrow and wide wakes behind the surface of the cylinder. Further, the St and mean Cd are observed to be increasing with respect to decrease in the transverse spacing ratio.

A Lattice Boltzmann Simulation of Cross-Flow Around Four Cylinders in a Square Arrangement

2010 ◽  
Author(s):  
J. Abolfazli Esfahani ◽  
A. R. Vasel Be Hagh
Keyword(s):  
Reynolds Number ◽  
Lattice Boltzmann Method ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Lattice Boltzmann ◽  
Cross Flow ◽  
Spacing Ratio ◽  
Volume Method ◽  
Boltzmann Method ◽  
Four Cylinders

The purpose of the present work is simulating cross flow around four cylinders in a square configuration by using a Lattice Boltzmann method. The effective parameters such as Reynolds number and spacing ratio L/D are chosen on the basis of former researches of other authors which have been done experimentally or by using traditional numerical schemes like finite volume method to provide the opportunity for comparing Lattice Boltzmann results with those obtained from experimental and CFD studies. Hence, the Reynolds number is set at Re = 100 and the spacing ratio is chosen to be 1.5, 2.5, 3.5, 4.5. It is shown that final results such as flow pattern, velocity and vorticity field are in accordance with those obtained by former researchers via experimental efforts or by use of finite volume method. This good agreement beside other important qualities such as efficient code, not having mesh tangling associated with other common numerical approaches, high convergence speed and nondimensional velocity and pressure field indicate this fact that in comparison with other numerical methods, Lattice Boltzmann method is very capable of analyzing a broad variety of fluid flows.

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