Numerical Investigation of “Frog-Leap” Mechanisms of Three Particles Aligned Moving in an Inclined Channel Flow

2015 ◽  
Vol 7 (2) ◽  
pp. 207-228 ◽  
Author(s):  
Xiao-Dong Niu ◽  
Ping Hu ◽  
Xing-Wei Zhang ◽  
Hui Meng ◽  
Hiroshi Yamaguchi ◽  
...  
Keyword(s):  
Channel Flow ◽  
Particle Surface ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Immersed Boundary ◽  
Inclined Channel ◽  
Channel Boundary ◽  
Boltzmann Method ◽  
Recent Experimental Work ◽  
Present Simulation

AbstractIntrigued by our recent experimental work (H. Yamaguchi and X. D. Niu, J. Fluids Eng., 133 (2011), 041302), the present study numerically investigate the flow-structure interactions (FSI) of three rigid circular particles aligned moving in an inclined channel flow at intermediate Reynolds numbers by using a momentum-exchanged immersed boundary-lattice Boltzmann method. A ”frog-leap” phenomenon observed in the experiment is successfully captured by the present simulation and flow characteristics and underlying FSI mechanisms of it are explored by examining the effects of the channel inclined angles and Reynolds numbers. It is found that the asymmetric difference of the vorticity distributions on the particle surface is the main cause of the “frog-leap” when particle moves in the boundary layer near the lower channel boundary.

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.

Numerical investigation for flow over a square rod through a passive control method at various Reynolds numbers

2020 ◽  
Vol 98 (5) ◽  
pp. 425-432
Author(s):  
A. Ahmed ◽  
R. Manzoor ◽  
S.U. Islam ◽  
H. Rahman
Keyword(s):  
Flow Regime ◽  
Passive Control ◽  
Control Method ◽  
Sudden Change ◽  
Flow Characteristics ◽  
Flow Regimes ◽  
Reynolds Numbers ◽  
Spacing Ratio ◽  
Boltzmann Method ◽  
Control Rods

This work presents a numerical simulation performed to study the effect of Reynolds number (Re = 80–200) on fluid flow over a square rod attached to two small controlling rods using the Lattice Boltzmann method. For this reason, the spacing ratio between the control rods and main rod varies systematically from g = 0.5–5. Flow has been subdivided into three flow regimes based on spacing ratios. The first flow regime is considered at a small gap (g = 0.5, 1, and 1.5), the second flow regime is obtained at a moderate gap (g = 2, 2.5, and 3), and the third flow regime is considered a at large gap (g = 4–5). Five different types of flow modes were noticed in the given flow regimes. The values Re = 200 and g = 5 were found to be critical due to a sudden change in flow characteristics. The maximum value of Cdmean is 0.869 and the largest percent reduction (65.15%) in the mean drag coefficient was found at Re = 200 and g = 2.

FLIGHT SIMULATIONS OF A TWO-DIMENSIONAL FLAPPING WING BY THE IB-LBM

2013 ◽  
Vol 25 (01) ◽  
pp. 1340020 ◽  
Author(s):  
YUSUKE KIMURA ◽  
KOSUKE SUZUKI ◽  
TAKAJI INAMURO
Keyword(s):  
Rotational Motion ◽  
Lattice Boltzmann ◽  
Translational Motion ◽  
Reynolds Numbers ◽  
Flapping Wings ◽  
Immersed Boundary ◽  
High Reynolds ◽  
The Stability ◽  
Boltzmann Method ◽  
Flight Simulations

The stability of flight by flapping wings is investigated by using the immersed boundary-lattice Boltzmann method (IB-LBM). First, the rotational motion with an initial small disturbance is computed, and it is found that the rotational motion is unstable for high Reynolds numbers. Second, we show simple ways to control the rotational and translational motion by bending or flapping the tip of the wing.

scholarly journals Simulation of Particle-Fluid Interaction in Fractal Fractures Based on the Immersed Boundary-Lattice Boltzmann Method

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Shenggui Liu ◽  
Songlei Tang ◽  
Jinkuang Huang ◽  
Mindong Lv ◽  
Yingjun Li
Keyword(s):  
Particle Size ◽  
Fractal Dimension ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Flow Characteristics ◽  
Immersed Boundary ◽  
Fluid Viscosity ◽  
Lower Permeability ◽  
Negative Exponential ◽  
Boltzmann Method

In order to reveal the influence of particles on fluid flow characteristics in rough fractures under fluid-solid coupling, a range of fracture systems with varying roughness were generated using the Weierstrass-Mandelbrot function. Fluid-particle interactions in rough fractal fractures were simulated using the immersed boundary-lattice Boltzmann method. In this paper, the effects of fluid viscosity, particle size, particle quantity, fracture fractal dimension, and particle grading composition are studied. Results illustrate that increasing fluid viscosity hinders the movement of particles, resulting in the decreasing of particle velocity. As particle size and particle quantity increase, the particle occupation of the channel area grows larger, which lead to lower permeability of the channel. Increasing fracture fractal dimension surges the curvature of the fluid channel, but permeability has a negative exponential correlation to fractal dimension. With increasing particle grading composition, the blocking effect of particles on fracture flow also increases with increasing particle proportion.

Study of unsteady separated fluid flows using a multi-block lattice Boltzmann method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Eslam Ezzatneshan
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Fluid Flows ◽  
Reynolds Numbers ◽  
Small Scale ◽  
Near Wake ◽  
Content Type ◽  
Boltzmann Method

Purpose Numerical simulations are performed for studying the vorticity dynamics of a dipole colliding with the wall in a bounded flow and the wake structure and separated flow properties past a circular cylinder at the values of Reynolds numbers. Design/methodology/approach The near wake statistics of separated fluid flows are investigated by using the lattice Boltzmann method (LBM) in a two-dimensional framework. A multi-block technique is applied to accurately resolve the flow characteristics by the grid refinement near the wall and preserve the stability of the numerical solution at relatively high Reynolds numbers. Findings The results show that the rolling-up of the boundary layer occurs due to the shear-layer instabilities near the surface which causes a boundary layer detachment from the wall and consequently leads to the formation of small-scale vortices. These shear-layer vortices shed at higher frequencies than the large-scale Strouhal vortices which result in small-scale high-frequency fluctuations in the velocity field in the very near wake. The present study also demonstrates that the efficiency of the multi-block LBM used for predicting the statistical features of flow problems is comparable with the solvers based on the Navier-Stokes equations. Practical implications Studying the separated flow characteristics in aerospace applications. Originality/value Applying a multi-block lattice Boltzmann method (LBM) for simulation of separated fluid flows at high-Reynolds numbers. Studying of the near wake statistics of unsteady separated fluid flows using the multi-block LBM. Comparison of flow characteristics obtained based on the LBM with those of reported based on the Navier-Stokes equations.

Flow Characteristics of Freely Rotating Rectangular Cylinders With Different Width to Height Ratios

2011 ◽  
Author(s):  
Y. G. Park ◽  
H. S. Yoon ◽  
M. Y. Ha
Keyword(s):  
Strouhal Number ◽  
Flow Characteristics ◽  
Periodic Oscillation ◽  
Reynolds Numbers ◽  
Immersed Boundary ◽  
Cylinder Surface ◽  
Oscillation Regime ◽  
Height Ratio ◽  
Volume Method ◽  
Rectangular Cylinders

The present study numerically investigates flow past freely rotating rectangular cylinders with different width to height ratios. The immersed boundary method (IBM) to model the rectangular cylinder based on the finite volume method is used to study a two-dimensional (2-D) laminar fluid flow for different Reynolds numbers of 50, 100, and 150 in the range of 0.2 ≤ W/H ≤ 1.0, where W/H is the width to height ratio. There are three different regimes of motion. The first one is the periodic oscillation regime. The second one is rotation with reversal of direction regime. The last one is the rotation with one direction regime. All the cases are periodic oscillation regime except the cases of Re = 100 and 150 with W/H = 1.0. For Re = 100 and 150 with W/H = 1.0, the regimes are the rotation with reversal of direction regime and the rotation with one direction regime, respectively. The Strouhal number decreases with increasing the width to height ratio for Re = 50, 100 and 150. However, for Re = 100 and 150, the Strouhal number disappears at a width to height ratio of 1.0. The present study reports the detailed information of flow structure on the cylinder surface at different width to height ratio.

Sign in / Sign up

Export Citation Format

Share Document