Numerical study of single bubble rising dynamics using the phase field lattice Boltzmann method

2018 ◽  
Vol 29 (11) ◽  
pp. 1850111 ◽  
Author(s):  
Ting Su ◽  
Yang Li ◽  
Hong Liang ◽  
Jiangrong Xu
Keyword(s):  
Reynolds Number ◽  
Bubble Size ◽  
Lattice Boltzmann ◽  
Viscosity Ratio ◽  
Density Ratio ◽  
Terminal Velocity ◽  
Single Bubble ◽  
Bubble Shape ◽  
Bubble Rising ◽  
Eotvos Number

In this paper, the rising dynamics of a two-dimensional single bubble in the duct is systematically studied by using an improved phase field lattice Boltzmann (LB) multiphase model. This model enables to handle multiphase flows with mass conservation and high density ratio, up to the order of [Formula: see text], which are unavailable in the LB community. The model is first validated by simulating bubble rising problem with the density ratio of 1000 and numerical solutions for bubble shape and position agree well with the previous literature data. Then, it is used to study single bubble rising through a quiescent liquid. The dynamic behavior of the bubble and rising velocity are shown, and the influences of several important physical quantities, including the Eotvos number, Reynolds number, density ratio, viscosity ratio, bubble size and initial bubble shape, are investigated in detail. The numerical results show that the bubble undergoes a great deformation with the increase of the Eotvos number or Reynolds number, and even could break up into multiple satellite bubbles at a sufficiently large value of Eotvos number or Reynolds number. Several classic terminal bubble shapes are also successfully produced in the system. The terminal rising velocity of bubble at equilibrium shows to present an initial increase with the Eotvos number and finally decreases with it, while increasing the Reynolds number could enhance the bubble rising velocity. Both the density ratio and viscosity ratio have less influence on the terminal shape of the bubble, while a greater influence on the rising velocity is reported for the density ratio smaller than 20 and it seems to be independent of the viscosity ratio. At last, we discuss the effects of the bubble size and initial bubble shape. It is found that bubble size has little influence on terminal bubble shape, but decreasing the bubble size can improve the bubble terminal velocity. On the other hand, both the deformation and terminal velocity of the bubble are found to no longer change much with its initial shape.

scholarly journals Numerical Simulation of Bubble Free Rise after Sudden Contraction Using the Front-Tracking Method

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Ying Zhang ◽  
Min Lu ◽  
Wenqiang Shang ◽  
Zhen Xia ◽  
Liang Zeng ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Front Tracking ◽  
Single Bubble ◽  
Tracking Method ◽  
Front Tracking Method ◽  
Sudden Contraction ◽  
Eotvos Number

Based on the front-tracking method (FTM), the movement of a single bubble that rose freely in a transverse ridged tube was simulated to analyze the influence of a contractive channel on the movement of bubbles. The influence of a symmetric contractive channel on the shape, speed, and trajectory of the bubbles was analyzed by contrasting the movement with bubbles in a noncontractive channel. As the research indicates, the bubbles became more flat when they move close to the contractive section of the channel, and the bubbles become less flat when passing through the contractive section. This effect becomes more obvious with an increase in the contractive degree of the channel. The symmetric contractive channel can make the bubbles first decelerate and later accelerate, and this effect is deeply affected by Reynolds number (Re) and Eötvös number (Eo).

Effects of Inertia and Viscosity on Single Droplet Deformation in Confined Shear Flow

2013 ◽  
Vol 13 (3) ◽  
pp. 706-724 ◽  
Author(s):  
Samaneh Farokhirad ◽  
Taehun Lee ◽  
Jeffrey F. Morris
Keyword(s):  
Reynolds Number ◽  
Shear Flow ◽  
Viscous Fluid ◽  
Lattice Boltzmann ◽  
Viscosity Ratio ◽  
Diffuse Interface ◽  
Single Droplet ◽  
Droplet Deformation ◽  
Droplet Dynamics ◽  
Lattice Boltzmann Simulations

AbstractLattice Boltzmann simulations based on the Cahn-Hilliard diffuse interface approach are performed for droplet dynamics in viscous fluid under shear flow, where the degree of confinement between two parallel walls can play an important role. The effects of viscosity ratio, capillary number, Reynolds number, and confinement ratio on droplet deformation and break-up in moderately and highly confined shear flows are investigated.

A Numerical Study of Jet Propulsion of an Oblate Jellyfish Using a Momentum Exchange-Based Immersed Boundary-Lattice Boltzmann Method

2014 ◽  
Vol 6 (3) ◽  
pp. 307-326 ◽  
Author(s):  
Hai-Zhuan Yuan ◽  
Shi Shu ◽  
Xiao-Dong Niu ◽  
Mingjun Li ◽  
Yang Hu
Keyword(s):  
Reynolds Number ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Numerical Study ◽  
Mass Density ◽  
Density Ratio ◽  
Large Mass ◽  
Immersed Boundary ◽  
Momentum Exchange ◽  
Boltzmann Method

AbstractIn present paper, the locomotion of an oblate jellyfish is numerically investigated by using a momentum exchange-based immersed boundary-Lattice Boltzmann method based on a dynamic model describing the oblate jellyfish. The present investigation is agreed fairly well with the previous experimental works. The Reynolds number and the mass density of the jellyfish are found to have significant effects on the locomotion of the oblate jellyfish. Increasing Reynolds number, the motion frequency of the jellyfish becomes slow due to the reduced work done for the pulsations, and decreases and increases before and after the mass density ratio of the jellyfish to the carried fluid is 0.1. The total work increases rapidly at small mass density ratios and slowly increases to a constant value at large mass density ratio. Moreover, as mass density ratio increases, the maximum forward velocity significantly reduces in the contraction stage, while the minimum forward velocity increases in the relaxation stage.

Study of the Effect of Wetting on Viscous Fingering Before and After Breakthrough by Lattice Boltzmann Simulations

2021 ◽  
Author(s):  
Peter Mora ◽  
Gabriele Morra ◽  
Dave Yuen ◽  
Ruben Juanes
Keyword(s):  
Reynolds Number ◽  
Oil Recovery ◽  
Lattice Boltzmann ◽  
Capillary Number ◽  
Viscosity Ratio ◽  
Viscous Fingering ◽  
Wetting Angle ◽  
Recovery Factor ◽  
Transition To Turbulence ◽  
Two Phase

Abstract We present a suite of numerical simulations of two-phase flow through a 2D model of a porous medium using the Rothman-Keller Lattice Boltzmann Method to study the effect of viscous fingering on the recovery factor as a function of viscosity ratio and wetting angle. This suite involves simulations spanning wetting angles from non-wetting to perfectly wetting and viscosity ratios spanning from 0.01 through 100. Each simulation is initialized with a porous model that is fully saturated with a "blue" fluid, and a "red" fluid is then injected from the left. The simulation parameters are set such that the capillary number is 10, well above the threshold for viscous fingering, and with a Reynolds number of 0.2 which is well below the transition to turbulence and small enough such that inertial effects are negligible. Each simulation involves the "red" fluid being injected from the left at a constant rate such in accord with the specified capillary number and Reynolds number until the red fluid breaks through the right side of the model. As expected, the dominant effect is the viscosity ratio, with narrow tendrils (viscous fingering) occurring for small viscosity ratios with M ≪ 1, and an almost linear front occurring for viscosity ratios above unity. The wetting angle is found to have a more subtle and complicated role. For low wetting angles (highly wetting injected fluids), the finger morphology is more rounded whereas for high wetting angles, the fingers become narrow. The effect of wettability on saturation (recovery factor) is more complex than the expected increase in recovery factor as the wetting angle is decreased, with specific wetting angles at certain viscosity ratios that optimize yield. This complex phase space landscape with hills, valleys and ridges suggests the dynamics of flow has a complex relationship with the geometry of the medium and hydrodynamical parameters, and hence recovery factors. This kind of behavior potentially has immense significance to Enhanced Oil Recovery (EOR). For the case of low viscosity ratio, the flow after breakthrough is localized mainly through narrow fingers but these evolve and broaden and the saturation continues to increase albeit at a reduced rate. For this reason, the recovery factor continues to increase after breakthrough and approaches over 90% after 10 times the breakthrough time.

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