Investigation of vortex shedding behind a porous square cylinder using lattice Boltzmann method

2010 ◽  
Vol 22 (5) ◽  
pp. 053605 ◽  
Author(s):  
V. Babu ◽  
Arunn Narasimhan
Keyword(s):  
Lattice Boltzmann Method ◽  
Vortex Shedding ◽  
Lattice Boltzmann ◽  
Square Cylinder ◽  
Boltzmann Method

Numerical simulation of flow over a square cylinder with upstream and downstream circular bar using lattice Boltzmann method

2018 ◽  
Vol 29 (04) ◽  
pp. 1850030 ◽  
Author(s):  
Yuan Ma ◽  
Rasul Mohebbi ◽  
M. M. Rashidi ◽  
Zhigang Yang
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Flow Patterns ◽  
Percentage Reduction ◽  
Square Cylinder ◽  
Distance Ratio ◽  
Maximum Percentage ◽  
Circular Bar ◽  
Boltzmann Method ◽  
Downstream Control

A numerical investigation is carried out to analyze the flow patterns, drag and lift coefficients, and vortex shedding around a square cylinder using a control circular bar upstream and downstream. Lattice Boltzmann method (LBM) was used to investigate flow over a square cylinder controlled by upstream and downstream circular bar, which is the main novelty of this study. Compared with those available results in the literature, the code for flow over a single square cylinder proves valid. The Reynolds number (Re) based on the width of the square cylinder ([Formula: see text]) and diameter of circular bar ([Formula: see text]) are 100 for square cylinder, 30 and 50 for different circular bars. Numerical simulations are performed in the ranges of [Formula: see text] and [Formula: see text], where [Formula: see text] and [Formula: see text] are the center-to-center distances between the bar and cylinder. Five distinct flow patterns are observed in the present study. It is found that the maximum percentage reduction in drag coefficient is 59.86% by upstream control bar, and the maximum percentage reduction in r.m.s. lift coefficient is 73.69% by downstream control bar. By varying the distance ratio for the downstream control bar, a critical value of distance ratio is found where there are two domain frequencies.

Simulation of Flow Past a Square Cylinder by Parallel Lattice Boltzmann Method using Multi-Relaxation-Time Scheme

2006 ◽  
Vol 22 (1) ◽  
pp. 35-42 ◽  
Author(s):  
J.-S. Wu ◽  
Y.-L. Shao
Keyword(s):  
Relaxation Time ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Reynolds Numbers ◽  
Numerical Results ◽  
Channel Height ◽  
Blockage Ratio ◽  
Square Cylinder ◽  
Single Relaxation Time ◽  
Boltzmann Method

AbstractThe flows past a square cylinder in a channel are simulated using the multi-relaxation-time (MRT) model in the parallel lattice Boltzmann BGK method (LBGK). Reynolds numbers of the flow are in the range of 100 ∼ 1,850 with blockage ratio, 1/6, of cylinder height to channel height, in which the single-relaxation-time (SRT) scheme is not able to converge at higher Reynolds numbers. Computed results are compared with those obtained using the SRT scheme where it can converge. In addition, computed Strouhal numbers compare reasonably well with the numerical results of Davis (1984).

FLOW EFFECT AROUND TWO SQUARE CYLINDERS ARRANGED SIDE BY SIDE USING LATTICE BOLTZMANN METHOD

2008 ◽  
Vol 19 (11) ◽  
pp. 1683-1694 ◽  
Author(s):  
YONG RAO ◽  
YUSHAN NI ◽  
CHAOFENG LIU
Keyword(s):  
Lattice Boltzmann Method ◽  
Vortex Shedding ◽  
Lattice Boltzmann ◽  
Reynolds Numbers ◽  
Small Space ◽  
Flip Flop ◽  
Drag And Lift Coefficients ◽  
Square Cylinders ◽  
Drag And Lift ◽  
Boltzmann Method

The flow around two square cylinders arranged side by side has been investigated through lattice Boltzmann method under different Reynolds numbers and various space ratios (s = d/D, d is the separation distance between two cylinders, D is the characteristic length) from 1.0, 1.1 to 2.7, including 18 space ratios. It is found that the flip-flop regime occurs at small space ratios and the synchronized regime occurs at large space ratios. Wide and narrow wakes at small spacing are formed and intermittently change behind the cylinders, and the biased flow in the gap is bistable. The frequency of vortex shedding is different in two wakes. The upper frequency is smaller than the lower frequency for small space ratios (s < 1.4), and the time-averaged drag and lift coefficients of cylinders are also different. When the space ratios increase, two distinct vortex streets occur behind the cylinders, and the frequency of vortex shedding is almost equal in two wakes. Also the difference of time-averaged drag and lift coefficients of the cylinders decreases with the increase in space ratios; in this case the flow shows synchronized regime. The transition between flip-flop and synchronized regimes occurs at s = 1.5. When s < 1.5, the flow shows flip-flop regime; otherwise, it shows synchronized regime. When s = 2.0 and 2.5, the curves for the time-averaged drag and lift coefficient with different Reynolds numbers are smooth. When s = 1.5 and 1.8, the curves are also smooth under Re ≤ 140, but that will be fluctuant under Re > 140 because of the nonlinear interaction between the wakes, and the instability of flow becomes stronger with the increase in Reynolds numbers. On the other hand, the vortex shedding type from the cylinder occurs in-phase when s < 2.5 and s = 2.5 for Re < 190, whereas that occurs anti-phase when s = 2.5 for Re ≥190. In addition, the pressure varies a little on the left surfaces and greatly on the right surfaces of both cylinders with the increase in Reynolds number at s = 2.5.

scholarly journals Effects of Wheel Rotation on Long-Period Wake Dynamics of the DrivAer Fastback Model

Fluids ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 19
Author(s):  
Matthew Aultman ◽  
Rodrigo Auza-Gutierrez ◽  
Kevin Disotell ◽  
Lian Duan
Keyword(s):  
Lattice Boltzmann Method ◽  
Motion Sickness ◽  
Vortex Shedding ◽  
Lattice Boltzmann ◽  
Low Frequency ◽  
Low Pressure ◽  
Side Force ◽  
Long Period ◽  
Total Vehicle ◽  
Boltzmann Method

Lattice Boltzmann method (LBM) simulations were performed to capture the long-period dynamics within the wake of a realistic DrivAer fastback model with stationary and rotating wheels. The simulations showed that the wake developed as a low-pressure torus regardless of whether the wheels were rotating. This torus shrank in size on the base in the case of rotating wheels, leading to a reduction in the low-pressure footprint on the base, and consequently a 7% decrease in the total vehicle drag in comparison to the stationary wheels case. Furthermore, the lateral vortex shedding experienced a long-period switching associated with the bi-stability in both the stationary and rotating wheels cases. This bi-stability contributed to low-frequency side force oscillations (<1 Hz) in alignment with the peak motion-sickness-inducing frequency (0.2 Hz).

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.

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