On Bubble Rising in Countercurrent Flow

2012 ◽  
Vol 10 (1) ◽  
Author(s):  
Marek Vecer ◽  
Pavel Lestinsky ◽  
Kamil Wichterle ◽  
Marek Ruzicka
Keyword(s):  
Surface Tension ◽  
Aspect Ratio ◽  
High Speed ◽  
Single Bubble ◽  
Viscous Liquids ◽  
Suitable Parameter ◽  
Theoretical Predictions ◽  
Bubble Rising ◽  
Bubble Rising Velocity ◽  
Eotvos Number

A single bubble of typical volume 20 mm³ ≤ VB ≤ 400 mm³ was placed in downward conically diverging flow of low and moderate viscous liquids (aqueous solutions of glycerine and of electrolytes (NaCl, Na3PO4, MgSO4), and butanol). Experiments were performed over a range of Reynolds number 60≤Re≤2200, Weber number 1≤We≤14, Tadaki number 1≤Ta≤10, Eötvös number 1≤Eo≤22, and bubble aspect ratio 0.4≤b/a≤0.9. The bubble shape, bubble position and motion were investigated by direct observation of two plane projection of bubble by high speed camera. Typical sampling frequency was 150 fps. Relatively long records, (approximately 9000 frames per one bubble observation) allow us to get relevant statistics of treated data. Bubble aspect ratio has been determined from both projection planes. Dimensionless front area of observed bubble has been introduced as suitable parameter for correlation with Eötvös number. Model of static bubble and classical Wellek correlation were employed as asymptotes. Bubble rising velocity has been determined and tested for each single bubble with respect to liquid properties. Velocity data are plotted within the frame given by several theoretical predictions for pure and contaminated liquids. Dimensional analysis is used considering viscosity and surface tension effect. New simple correlation of bubble rising velocity separating the effects of viscosity and surface tension is presented.

Investigation of single bubble rising velocity in LBE by transparent liquids similarity experiments

2018 ◽  
Vol 108 ◽  
pp. 204-213 ◽  
Author(s):  
Chaodong Zhang ◽  
Danna Zhou ◽  
Rongyuan Sa ◽  
Qingsheng Wu
Keyword(s):  
Single Bubble ◽  
Bubble Rising ◽  
Bubble Rising Velocity

The effects of surface tension and tube inclination on a two-dimensional rising bubble

1987 ◽  
Vol 184 ◽  
pp. 1-14 ◽  
Author(s):  
Benoit Couët ◽  
Gary S. Strumolo
Keyword(s):  
Surface Tension ◽  
Froude Number ◽  
Excellent Agreement ◽  
Experimental Results ◽  
Large Bubble ◽  
Continuous Derivative ◽  
Two Dimensional ◽  
Rising Bubble ◽  
Theoretical Predictions ◽  
Bubble Rising

The effects of surface tension σ and tube inclination β on the Froude number Fr of a large bubble rising in a two-dimensional duct is considered. It is found that there exists either one (for small σ and β > 0°) or a set (for any σ and β = 0°) of Fr-values for which the bubble has a continuous derivative at the nose. By selecting either this single Fr (or the maximum of the set), we obtain solutions in excellent agreement with both theoretical predictions and experimental results.

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.

The Drag Coefficient and the Shape for a Single Bubble Rising in Non-Newtonian Fluids

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Shaobai Li ◽  
Youguang Ma ◽  
Shaokun Jiang ◽  
Taotao Fu ◽  
Chunying Zhu ◽  
...  
Keyword(s):  
Drag Coefficient ◽  
High Speed ◽  
Newtonian Fluids ◽  
Single Bubble ◽  
Dynamical Characteristic ◽  
Wide Range ◽  
Coefficient Corrélation ◽  
Deformed Bubble ◽  
Bubble Rising ◽  
Experimental Values

The dynamical characteristic of a single bubble rising in non-Newtonian fluid was investigated experimentally. The bubble aspect ratio and rising velocity were measured by high speed camera. The shape regimes for bubbles in non-Newtonian fluids was plotted by means of Reynolds number Re, Eötvös number Eo and Morton number Mo. The effects of bubble shape and liquid rheological property on the total bubble drag coefficient were studied. A new empirical drag coefficient correlation covering spherical bubble and deformed bubble was proposed, the predicted results shows good conformity to experimental values over a wide range of 0.05 < Re < 300.

Experimental Study of Single-Bubble Dynamics in Isothermal Liquid Pools: Effects of Fluid Properties, Orifice Diameter and Flow Rate

2007 ◽  
Author(s):  
A. Subramani ◽  
M. A. Jog ◽  
R. M. Manglik
Keyword(s):  
Surface Tension ◽  
Flow Rate ◽  
High Speed ◽  
Bubble Dynamics ◽  
Processing System ◽  
Single Bubble ◽  
Orifice Diameter ◽  
Growth Time ◽  
Interfacial Behavior ◽  
Fluid Properties

The dynamics of a single bubble as it grows at and eventually detaches from the tip of submerged capillary orifices in isothermal pools of pure liquids of varying fluid properties is studied experimentally. The transient interfacial behavior around the evolving isolated bubble (from inception through growth, necking, and detachment) is mapped by means of optical micro-scale flow visualization that uses a high-speed high-resolution digital camera and image processing system. Parametric effects of capillary orifice diameter (do = 0.32, 1.0, and 1.76 mm), air flow rate (2 ≤ Q˙ ≤ 20 ml/min), and liquid properties (surface tension and viscosity), on the bubbling signature (growth time, departure diameter, and bubble interval) are explored and highlighted. It is found that bubble evolution, in a first order scaling, can be correlated by a balance of forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport at the transient gas-liquid interface.

SIMULATION OF AN AXISYMMETRIC RISING BUBBLE BY A MULTIPLE RELAXATION TIME LATTICE BOLTZMANN METHOD

2009 ◽  
Vol 23 (24) ◽  
pp. 4907-4932 ◽  
Author(s):  
ABBAS FAKHARI ◽  
MOHAMMAD HASSAN RAHIMIAN
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Rise Velocity ◽  
Rising Bubble ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Multiple Relaxation Time ◽  
Bubble Rising ◽  
Boltzmann Method

In this paper, the lattice Boltzmann method is employed to simulate buoyancy-driven motion of a single bubble. First, an axisymmetric bubble motion under buoyancy force in an enclosed duct is investigated for some range of Eötvös number and a wide range of Archimedes and Morton numbers. Numerical results are compared with experimental data and theoretical predictions, and satisfactory agreement is shown. It is seen that increase of Eötvös or Archimedes number increases the rate of deformation of the bubble. At a high enough Archimedes value and low Morton numbers breakup of the bubble is observed. Then, a bubble rising and finally bursting at a free surface is simulated. It is seen that at higher Archimedes numbers the rise velocity of the bubble is greater and the center of the free interface rises further. On the other hand, at high Eötvös values the bubble deforms more and becomes more stretched in the radial direction, which in turn results in lower rise velocity and, hence, lower elevations for the center of the free surface.

Prediction of Ball Motion in High-Speed Thrust-Loaded Ball Bearings

1976 ◽  
Vol 98 (3) ◽  
pp. 463-469 ◽  
Author(s):  
C. R. Gentle ◽  
R. J. Boness
Keyword(s):  
Computer Program ◽  
High Speed ◽  
Ball Bearing ◽  
Viscoelastic Behavior ◽  
Specific Situation ◽  
Fluid Models ◽  
Ball Bearings ◽  
Theoretical Predictions ◽  
Ball Motion

This paper describes the development of a computer program used to analyze completely the motion of a ball in a high-speed, thrust-loaded ball bearing. Particular emphasis is paid to the role of the lubricant in governing the forces and moments acting on each ball. Expressions for these forces due to the rolling and sliding of the ball are derived in the light of the latest fluid models, and estimates are also made of the cage forces applicable in this specific situation. It is found that only when lubricant viscoelastic behavior is considered do the theoretical predictions agree with existing experimental evidence.

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