scholarly journals Comparison of Two Solvers for Simulation of Single Bubble Rising Dynamics: COMSOL vs. Fluent

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 452
Author(s):  
Jakub Crha ◽  
Pavlína Basařová ◽  
Marek C. Ruzicka ◽  
Ondřej Kašpar ◽  
Maria Zednikova
Keyword(s):  
Rotational Symmetry ◽  
Current Trend ◽  
Bubble Velocity ◽  
Comsol Multiphysics ◽  
Ansys Fluent ◽  
Rising Bubble ◽  
Spherical Bubbles ◽  
Bubble Rising ◽  
Experimental Values ◽  
Parasitic Currents

Multiphase flows are a part of many industrial processes, where the bubble motion influences the hydrodynamic behavior of the batch. The current trend is to use numerical solvers that can simulate the movement and mutual interactions of bubbles. The aim of this work was to study how two commercial CFD solvers, COMSOL Multiphysics and Ansys Fluent, can simulate the motion of a single rising bubble in a stagnant liquid. Simulations were performed for spherical or slightly deformed bubbles (Db = 0.6, 0.8, and 1.5 mm) rising in water or in propanol. A simple 2D axisymmetric approach was used. Calculated bubble terminal velocities and bubble shape deformations were compared to both experimental data and theoretical estimations. Solver Comsol Multiphysics was able to precisely calculate the movement of smaller and larger bubbles; due to the 2D rotational symmetry, better results were obtained for small spherical bubbles. The deformation of larger bubbles was calculated sufficiently. Solver Ansys Fluent, in the setting used, failed to simulate the motion of small bubbles due to parasitic currents but allowed for modeling of the motion of larger bubbles. However, the description of the bubble velocity and shape was worse in comparison with experimental values.

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.

Mixing of Matter by a Rising Bubble Near a Wall

2011 ◽  
Author(s):  
Toru Koso ◽  
Hiroyuki Iwashita ◽  
Fumihiko Usuki
Keyword(s):  
Large Scale ◽  
Uv Light ◽  
Fluid Motion ◽  
Turbulent Diffusion Coefficient ◽  
Air Bubble ◽  
Rising Bubble ◽  
Mass Dispersion ◽  
Mixing Patterns ◽  
Bubble Rising ◽  
Near Wall

The turbulent mixing of liquid mass caused by an air bubble rising near a wall in a still liquid in a pipe is investigated experimentally using a photochromic dye. A part of the liquid is activated by UV light and subjected to the fluid motion caused by a zigzag rising bubble of which Reynolds number is 214. The visualized mixing patterns showed that the dye is mixed by vortex motions in the bubble wake that is similar to the case of a bubble rising in the center of the pipe. The concentration distributions were deduced from the dye images using Lambert-Beer’s law and the turbulent diffusion coefficient (TDC) was evaluated from the temporal changes in the mass dispersion. The TDCs showed that a near-wall bubble generates stronger mixing than for a bubble in the center of the pipe. This stronger mixing can be attributed to the large-scale vortices observed for a near-wall bubble, which remains active for a longer time due to the lack of oppositely rotating vortices and mixes more fluids.

The Effect of Electromagnetic Field on the Behavior of Bubbles

2013 ◽  
Author(s):  
Hong-bo Liu ◽  
Liang-ming Pan
Keyword(s):  
Electromagnetic Field ◽  
Three Dimensional ◽  
Mhd Flow ◽  
Liquid Pool ◽  
Single Bubble ◽  
Uniform Electric Field ◽  
Rising Bubble ◽  
Homogenous Distribution ◽  
Bubble Rising ◽  
Two Bubbles

The coalescence and motion behaviors of bubbles can be influenced by electromagnetic field, it can be found in the TOKAMK fusion reactors of ITER program. In this paper, VOF (Volume of Fluid) method is adopt to simulate the single bubble rising behavior and bubble coalescence in stagnant liquid under the electromagnetic field within a cylinder closure (D = 20mm, H = 50mm). A three-dimensional numerical simulation is presented considering the driving effect of uniform electric field and magnetic field on the process of bubble rising and bubbles inline coalescence in stagnant liquid pool. The interesting local Magneto-hydrodynamic (MHD) flow, which is produced due to current non-homogenous distribution around the insolated gas bubble, is discussed in the process of single bubble rising and coalescence of bubbles inline. Under the influence of local MHD flow, the rising bubble shape presents obvious deformation. More importantly, as the existence of rotating Lorentz force, the liquid film between two bubbles is stirred, the process of coalescence is largely accelerated.

Numerical Study on Gas-Yield Power-Law Fluid in T-Junction Minichannel

2019 ◽  
Author(s):  
Abdalsalam Ihmoudah ◽  
Mohamed M. Awad ◽  
Aziz Rahman ◽  
Stephen D. Butt
Keyword(s):  
Film Thickness ◽  
Power Law ◽  
Xanthan Gum ◽  
Numerical Study ◽  
Superficial Velocity ◽  
Bubble Velocity ◽  
Two Phase ◽  
Ansys Fluent ◽  
Power Law Fluids ◽  
Taylor Bubbles

Abstract In this study, a computational examination of Taylor bubbles was performed for gas/non-Newtonian fluid two-phase flows developed in a minichannel T-junction mixer with a hydraulic diameter of 1 mm. The investigations employed three separate aqueous xanthan gum solutions at concentrations of 0.05, 0.1 and 0.15 w/w, which are referred to as non-Newtonian (yield power-law) fluids. The effective concentration of the xanthan gum solutions and superficial velocity of the inlet liquid phase on the length, velocity, and shape of the Taylor bubbles was studied using the ANSYS FLUENT 19 software package. The simulation results show an increase in bubble velocity with increasing film thickness, particularly in solutions of higher viscosity XG-0.15%. Furthermore, bubble lengths decreased as the xanthan gum concentrations increased, but bubble shapes underwent alterations when the concentrations increased. Another interesting result of the tests shows that when the liquid inlet velocity increases, bubble lengths decrease during lower liquid superficial velocity, whereas during higher velocities, they change only slightly after increases in concentration. Finally, with increasing XG concentration, the liquid film thickness around the bubble increased. The results show good agreement with correlations after modifying a capillary number (Ca*) for non-Newtonian liquids in all cases.

Review of potential flow solutions for velocity and shape of long isolated bubbles in vertical pipes

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alexandre Boucher ◽  
Roel Belt ◽  
Alain Liné
Keyword(s):  
Potential Flow ◽  
Bubble Velocity ◽  
Past Century ◽  
Theory Approach ◽  
Total Derivative ◽  
Power Series Method ◽  
Derivative Method ◽  
Bubble Rising ◽  
Analytical Tools ◽  
Moving Liquid

Abstract The motion of elongated gas bubbles in vertical pipes has been studied extensively over the past century. A number of empirical and numerical correlations have emerged out of this curiosity; amongst them, analytical solutions have been proposed. A review of the major results and resolution methods based on a potential flow theory approach is presented in this article. The governing equations of a single elongated gas bubble rising in a stagnant or moving liquid are given in the potential flow formalism. Two different resolution methods (the power series method and the total derivative method) are studied in detail. The results (velocity and shape) are investigated with respect to the surface tension effect. The use of a new multi-objective solver coupled with the total derivative method improves the research of solutions and demonstrates its validity for determining the bubble velocity. This review aims to highlight the power of analytical tools, resolution methods and their associated limitations behind often well-known and wide-spread results in the literature.

The Change of Velocity and Pressure of Micro Bubble in Multi-Phases Flow in Mesoscopic Scale

2014 ◽  
Vol 722 ◽  
pp. 97-100 ◽  
Author(s):  
Zai Shuai Ling ◽  
Wei Long ◽  
Zhang Yong Wu
Keyword(s):  
Bubble Velocity ◽  
Dissolution Mechanism ◽  
Flow State ◽  
Mesoscopic Scale ◽  
Vof Model ◽  
Key Factor ◽  
Micro Bubble ◽  
Fluent Software ◽  
Bubble Rising ◽  
Pressure Changes

The dissolution mechanism of air and formation mechanism of bubble in the scopic-scale,and the change rule of the velocity and pressure of bubble in the rising process,made the theoretical analysis and explanation. Be based on VOF model,with the help of Fluent software,For the single bubble rising in the water by numerical simulation;The results show that liquid phase flow state is a key factor affecting the speed of the bubbles rise;Pressure difference is the main reason cause the jets and bubbles deformation.Through the above process in the rising process of the bubble velocity and pressure changes, and a detailed analysis of inquiry, the pressure and velocity of the bubble rising process show up more realistic.

Drag and Mass Transfer of Bubble Swarms in Power-Law Liquids at Moderate Reynolds and Peclet Numbers

2007 ◽  
Author(s):  
N. Kishore ◽  
R. P. Chhabra ◽  
V. Eswaran
Keyword(s):  
Mass Transfer ◽  
Power Law ◽  
Cell Model ◽  
Active Material ◽  
Liquid System ◽  
Numerical Results ◽  
Wide Range ◽  
Spherical Bubbles ◽  
Bubble Rising ◽  
Surface Active Material

The motion and mass transfer of swarms of mono-size non-circulating spherical bubbles (without any surface active material) in power-law liquids have been numerically investigated at moderate Reynolds and Peclet numbers. A simple sphere-in-a-sphere cell model has been used to account for hydrodynamic interactions between neighbouring bubbles. A wide range of values of gas hold-up has been considered so as to evaluate the detailed drag and mass transfer characteristics of swarms of bubbles to almost single bubble rising in power-law liquids. Extensive numerical results have been obtained to elucidate the effects of the Reynolds number (Re), power-law index (n) and gas hold-up (φ) on the drag coefficients and Sherwood numbers over the ranges of conditions: 0.6 ≤ φ ≤ 10−6, 1 ≤ Re ≤ 200, 1 ≤ Sc ≤ 1000 and 0.6 ≤ n ≤ 1.6. The total drag coefficient (CD) decreases with the decreasing values of n, whereas, the average Sherwood number (Shavg) decreases with increasing values of n. Based on the present numerical results simple predictive correlations have been proposed for CD and Shavg which can be used to estimate the free rising velocity and the rate of mass transfer in a gas-liquid system in a new gas-liquid application.

Calculation of Effect of Viscous and Pressure Forces on Trimming Moments

2014 ◽  
Vol 590 ◽  
pp. 42-47
Author(s):  
Salma Sherbaz ◽  
Wen Yang Duan
Keyword(s):  
Computational Methods ◽  
Reasonable Agreement ◽  
Volume Of Fluid ◽  
Wave Profile ◽  
Computational Domain ◽  
Implicit Methods ◽  
Ansys Fluent ◽  
Hull Form ◽  
Experimental Values

In this study the effects of viscous and pressure forces on trimming moments of Series 60 (CB = 0.6) hull form are calculated at different Froude numbers by employing computational methods. The grid generator GAMBIT was used for meshing hull and computational domain. The Simulations are carried out using commercial CFD code ANSYS Fluent 13. The SIMPLE (Semi-Implicit Methods for Pressure-Linked Equations) algorithm is used for pressure-velocity coupling. The volume of Fluid (VOF) formulation is employed. The computed resistance, wave profile and trim of series 60 hull are compared with experimental values and found in reasonable agreement.

Numerical Simulation of Bubbles Contaminated With Soluble Surfactant

2011 ◽  
Author(s):  
Ryo Kurimoto ◽  
Kosuke Hayashi ◽  
Akio Tomiyama
Keyword(s):  
Peak Concentration ◽  
Marangoni Effect ◽  
Bulk Liquid ◽  
Low Viscosity ◽  
Spherical Bubbles ◽  
Soluble Surfactants ◽  
Bubble Rising ◽  
Bubble Rising Velocity ◽  
Vertical Duct ◽  
Soluble Surfactant

An interface tracking method for predicting motions of bubbles contaminated with soluble surfactants is presented. A level set method is utilized to track the interface. Transportations of surfactants in the bulk liquid and those at the interface are taken into account. The amount of adsorption and desorption is evaluated by using the Frumkin & Levich model. Simulations of bubbles contaminated with soluble surfactants are carried out, i.e., single air bubbles rising through stagnant water, Taylor bubbles in a vertical pipe filled with water, and a wobbling bubble in a vertical duct. As a result, the following conclusions are obtained: (1) the increase in drag coefficients of spherical bubbles due to the presence of surfactant, i.e. Marangoni effect, is well predicted, (2) surfactants mainly accumulate at the rear edge of a Taylor bubble and the Marangoni effect is very small in the nose region at high Eo¨tvo¨s and low Morton numbers, and therefore, the effects of surfactant on the bubble rising velocity are small in low viscosity systems, and (3) the surfactant concentration is low in the top region of a wobbling bubble, whereas it is high in the bottom region. The peak concentration appears at the side edge of the bubble and the location of the peak concentration moves with the bubble and wake movements.

scholarly journals Technical Note: How image processing facilitates the Rising Bubble Technique for discharge measurement

2011 ◽  
Vol 8 (5) ◽  
pp. 8499-8531
Author(s):  
K. P. Hilgersom ◽  
W. M. J. Luxemburg
Keyword(s):  
Image Processing ◽  
Water Surface ◽  
Effective Means ◽  
Technical Note ◽  
Laboratory Setup ◽  
Rising Bubble ◽  
Recent Developments ◽  
Bubble Rising ◽  
Bubble Rising Velocity ◽  
Discharge Measurements

Abstract. In this article, we rehabilitate the integrating rising bubble technique as an effective means of obtaining discharge measurements. Since Sargent (1981, 1982a), the technique has not been applied widely, mainly as a result of practical difficulties. We hypothesize that modern image processing techniques can greatly improve the rising bubble technique. We applied the technique in both a laboratory setup and a field study, after calibrating the bubble rising velocity for our nozzles in the specific case. During our measurements, we captured digital photographs of the bubble envelope at the water surface, each picture being a single measurement of the discharge. The photographs were corrected for lens distortion and reprojected so that accurate distances on water surface level could be obtained. This easy digital procedure resulted in accurate discharge measurements, even when turbulence was involved and the averages of multiple image analyses yielded good results. The study shows that the rising bubble technique can be a preferable discharge gauging technique in some situations. Recent developments in image processing facilitate the method substantially.

Sign in / Sign up

Export Citation Format

Share Document