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During the nucleate boiling numerical simulation of bubble growth using ANSYS Fluent, what is mean by bubble seed? Do we have to insert the bubble during modelling itself?
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Bubble seed refers to nucleation phenomena at the origin of bubble for formation. When the liquid is “seeded” homogeneously with a certain number of tiny vapour bubbles They will start to grow as soon as the liquid becomes “saturated” (P = Psat(T0 )) and correspondingly vapour volume fraction starts to increase as a result of phase change.
SEE:
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I am looking for reasoned / reasonable explanations of the dynamic behavior of bulk and surface nanobubbles.
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I do get the full scenario you have in mind, but it sounds more like if you have mobilities reacting on driving forces like concentration gradients and interface curvature. In such a case diffusional fluxes related, at a given time, with a classical 1st Fick's law might imply a curvature dependent diffusion coefficient. Such a case I, however, would not interpret in terms of a curvature dependent diffusion coefficient, but instead (see above) in terms of a curvature- and concentration-gradient independent mobility which determine the fluxes.
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Hi
Can anyone please shed some light on Morton number and its physical significance? Where it is a must to use Mo instead of Bond number or Eotvos number and why? 
Thanks.
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In the case of bubble dynamics, we study the effect of Eo number on the shape instabilities of the rising bubble. However, Eo number contains the radius of the bubble which is actually changing continuously with time. Thus, there is a need to define Morton number which depends only on the fluid properties and not on the bubble radius. Morton number is a suitable ratio of Eo and Ga numbers so as to eliminate the bubble radius.
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I am working on Ultrasound Contrast Micro bubbles. I am from Medical background with little Knowledge of Medical Physics. kindly Guide me to some book or video lectures regarding Theoretical Models for estimation of Bubble dynamics ....
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Dear Ramish,
It may be worth linking direcrly with the corresponding authors of the papers you read, so that they will give you specific guidelines on their mathematical models and logic behind them.
Very good luck,
Giorgos
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Dea experts,
I am working in the field of polyurethane synthesis. I would kindly ask it there is any method and/or techinique suitable to add liquid pentane (blowing agent) to the polyol phase with no air bubble inclusion due to the mixing of these two components.
Thanks in advance
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Adding a few drops of antifoam may help. Also don't mix too violently nor for too long.
Alain
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Explanation:
I want to track the gravity center of two bubbles rising in a liquid through VOF simulation. the algorithm which i was using before for the study of single bubble is giving only the gravity center of 1st registered bubble(In the case of 2 bubbles).
do we have any other method or algorithm ?
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you may have to adopt some things for your needs.
Best regards
Christian
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Does using porous sparger any effect on ozone bubble destruction?
I was measuring ozone yield of lab-scale ozone generator. For about 15 cm height of sample, using porous sparger decreases the amount of ozone delivered to the sample.
Assuming the fact that using sparger would increase mass transfer, what can be the reason of this result?
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Hi,
I agree with Dr. Frank ... You need to give more informations about your operating conditions (gas pressure and flow, T°, pH of your liquid, ... )
There are many factors to be considered in your experiment to optimize the O3 solubility. First at all, try to increase the height of your sample ...
Kind regards
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Hello everyone
I wanted to simulate a continuous operation reactor. The gas and liquid phases enter the reactor from the bottom, and the reactor was initially filled with liquid phase.
The attachment is my model of simulation.
The problem I had was
(1) I choose pressure outlet as the boundary condition in ANSYS Fluent. But when I put PBM into simulation, I found that have to set boundary value of bin fraction. Are these values obtained through the experiment?
(2) How to set backflow volume fraction to make calculations more stable in continuous operation mode
(3) When I put PBM into the simulation the residuals shoot up after a few iteration. Is there any tips to make the calculation converge in CFD-PBM simulation?
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Xiangfei Jia : This error message essentially means, that the system of turbulence model equations either does not converge or is shortly before a straight divergence. The set boundary conditions for turbulence and the URF's should be checked. Eventually further measures for convergence improvement are necessary. I would further recommend to switch to the SST model. In particularly close to boundaries the SST model uses the k-omega turb. model formulation, which is bounded for both k and omega and does not produce arbitrarily high values for the turbulence properties.
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I want to get raw signal (Voltage-Time) from Hydrophone (in bubble flow and air injection experiment) . What should I use in the distance between Hydrophone and PC(Software)? Which type of acquisition&amplifier? Or which equipment I need?
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Depending on how fine a time scale you need and what signal amplitudes are produced by your microphone, you might be fine without extra amplifying/filtering/processing equipment.
You can plug your mic into your computer and access the waveform with MATLAB, see https://www.mathworks.com/help/audio/gs/real-time-audio-in-matlab.html.
If the signal is saturating the mic input or is too small to detect, get an amplifier to perform the necessary increase or reduction of voltage. Also, make sure that it works in the frequency range you are interested in.
If the the time resolution is not fine enough, you need to find some sort of analog to digital converter (ADC) like a PC-card oscilloscope that has a sampling rate high enough for your purposes. MATLAB and Labview are good options to look for when choosing a PC-card o-scope. These scopes are expensive but can handle higher frequency signals and the min/max voltage can sometimes be selected from a list, possible making the amplitude matching amplifier unnecessary.
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I am working on VOF, i am simply doing it for isolated bubble rise in air water system.its 2D simulation
I want to know How to determine dia and terminal velocity of bubble?
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Probably you found an answer to your question in the meantime; however, since it is a common question of students, I want to add that you do not need to track the center or anything else. Simply use the mass averaged velocity (momentum):
let K the phase indicator function (1 for gas 0 for liquid), V the velocity vector, vol the volume of your cell (area in 2D), and sum() the summation over all your cells
bubble velocity = sum(vol*K*V)/sum(vol*K)
slip velocity = sum(vol*K*V)/sum(vol*K) - sum(vol*(1-K)*V)/sum(vol*(1-K))
[If you run compressible simulations, you must use vol*rho_gas and vol*rho_fluid]
2D bubble diameter : sqrt( 4*sum(vol*K)/Pi )
[this is the Area-circle equivalent diameter]
3D bubble diameter : cbrt ( 6*sum(vol*K)/Pi )
[this is the spherical equivalent diameter]
You can evaluate the bubble shape by searching the bounding box if it is a non-wobbling bubble - find the max and min x, y, and z of your PLIC reconstruction, zero-level when you use level set, or of your boundary compression when you use two-fluid model. For wobbling bubbles, different definitions of "shape" exist - be consistent with the experiment you want to compare.
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I'm looking for a new method of producing microbubbles of useless/cheap gases for flotation/separation uses.
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using a small ventrui tube can generate 0.2-0.3mm fine bubbles.
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Hi All
I am working on 2D air/water system with VOF model. I am calculating the bubble velocity by pointing surface and then dividing with time, surely this is not the exact terminal velocity.
My case works on buoyancy forces (No inlet to the system). If there is any UDF or any tutorial guide me so that i can calculate both the bubble center(wrt to co-ordinates) and the shape of bubble.
thanks in Advance
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The final target is to study the fundamental physical processes involved in bubble dynamics and the phenomenon of cavitation. Develop a new bubble dynamics CFD model to study the evolution of a suspension of bubbles over a wide range of vesicularity, and that accounts for hydrodynamical interactions between bubbles while they grow, deform under shear flow conditions, and exchange mass by diffusion coarsening. Which commercial/open source CFD tool and turbulence model would be the most appropriate ones?
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It would be a highly educational experience if you could try to develop your own solver using MATLAB then write it in a low-level programming environment like Fortran.
But OpenFOAM should be sufficient if you want to get a bit better at programming CFD, and ANSYS/Fluent would be best if you plan on proceeding as a CFD user.
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I am trying to model rise of CO2 bubble in a pond.
I am using this correlation:
Cd=18.5/Re^(0.6), when Re<1000
Cd=0.44, when Re>=1000
Cd=drag coefficient.
Re=rho_liquid*Vbubble*dbubble/mu_liquid (Reynolds number)
vbubble=(4*dia_bubble*g/3/Cd)^(1/2) (Rise Velocity in m/s)
Here is how I am currently solving this:
Assume Re>1000
vbubble=(4*dia_bubble*g/3/0.44)^(1/2)
for d_bubble=0.003 m
I get vbubble =0.29m/s
but Re= 986 (for T=298K)
so this fails.
Next assumption Re<1000
I get vbubble= 0.4 m/s
Re=1311.4
This also fails.
Hence I am unable to solve this. What to do in this case?
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Well, plot the function and you will see. Our correlation is just a little bit more accurate in the end (the experimental data reach 0.40 (!) at Re = 3000 . A power function does not 'easily' end in an asymptote (0.44). You may try to use your correlation with a boundary of 500...
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Dear colleagues, specially who treat with problems containing bubbles in different fluids.
Based on your experience, let us discuss about the main differences between gas bubble and vapour bubble in two/multi-phase flow. Properties of their contents, surrounding fluid, their behaviour in growth/collapse/oscillation... etc.
Thanks in advance.
Yours, Khaled.
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Dear Colleagues, 
Best greetings and my best wishes for good health and long life for you.
    My work focus on solving bubble dynamics problems analytically,  I am glad If you provide me by any good paper that deals with solving such problems analytically.
Regards
Khaled
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Hi,
You can use the last edition of this book. It is vey useful.
Zapryanov, Z., & Tabakova, S. (2013). Dynamics of bubbles, drops and rigid particles (Vol. 50). Springer Science & Business Media.
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Maybe via the formation of larger bubbles which have higher rising velocity and result in the decrease of the respective residence time? If so, why shear-thinning behavior promotes the formation of larger bubbles?
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Dear Sekhar,
Thank you very much
Best regards,
Petros
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I have PDB files from MD simulation and would like to calculate hydrodynamic radius (RH). I tried using HYDROPRO. It provides translational diffusion coeff. and Radius of gyration. from which RH should be derived. buT if some can walk me through that will be great. 
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Note that in biophysics, hydrodynamic radius refers to the Stokes radius,[2] or commonly to the apparent Stokes radius obtained from size exclusion chromatography.[3]
The theoretical hydrodynamic radius Rhyd refers to the Stokes radius,
arises in the study of the dynamic properties of polymers moving in a solvent. It is often similar in magnitude to the radius of gyration
[quote]
The radius of gyration is not that tough. Here's a python script to do
it in pymol. Do note that the hydrodynamic radius is something
related, but different.
from pymol import cmd
import math
def rgyrate(selection):
# Get the atoms for the selection
model=cmd.get_model(selection).atom
# Extract the coordinates
x=[i.coord for i in model]
# Get the masses
mass=[i.get_mass() for i in model]
# Mass-weighted coordinates
xm=[(m*i,m*j,m*k) for (i,j,k),m in zip(x,mass)]
# Sum of masses
tmass=sum(mass)
# First part of the sum under the sqrt
rr=sum(mi*i+mj*j+mk*k for (i,j,k),(mi,mj,mk) in zip(x,xm))
# Second part of the sum under the sqrt
mm=sum((sum(i)/tmass)**2 for i in zip(*xm))
# Radius of gyration
rg=math.sqrt(rr/tmass-mm)
# Print it...
print "Radius of gyration:", rg
return rg
cmd.extend("rgyrate",rgyrate)
Hope it helps,
Tsjerk
[/quote]
In contrast to the formula for the hydrodynamic radius in Wikipedia, this script weights the atoms by their mass
Program HydroPro calculate hydrodynamic radius from pdb (windows/linux executable) http://leonardo.inf.um.es/macromol/programs/programs.htm
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UCLA Putterman Research Group fond that:
Sonoluminescence from xenon bubbles in water driven by a sound field with a frequency of 1 MHz. A flash of light is emitted as the implosion reaches 100 nm in size. The spectrum has all colors ranging from far UV to infrared. The sun is a 5,800 K blackbody and this bubbles is more ultraviolet than a 10,000 K blackbody. 
My questions are the following:
1- Is it possible to observe this phenomenon each time when introduced a bubble of Xenon?
2- Is it possible to repeat this experiment several times (tens or hundreds times) for the same water sample?
Best regards
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I am unsure what you mean by several times, during the sonication process there will be many bursts of light. If you are talking about experimentation for a set time period, then turning everything off and starting again then I do not have a direct answer to this question as it depends on several other factors. 
In short, the liquid properties will change. For example, at high frequency there will be an increase in the quasi acoustic streaming that takes place, this in turn can cause agitation at the liquid surface and increase the gas content of the solution. Also what powers would you be using? At higher powers there is an increase in streaming, coalescence and temperature of solution. Whilst gas is lost during sonication, streaming can aid in replacing the gas content. Coalescence can cause degassing and lead to a reduction in the numbers of SL bubbles (although at high frequencies coalescence can be beneficial). The temperature of the solution can have a significant role on the amount of SL taking place, therefore for long sonication times may be an issue. 
Coming back to your original question, In my opinion yes, it is possible. Cavitation cycles can last millions if not billions of cycles, BUT what I'm trying to explain above is that, the amount of light emission will not remain constant and can decrease significantly. The amount of light emission will depend on how the properties of the fluid change over time. 
Why would you want to use the same solution?
It depends on the aims of your experiment, I am unsure what you are trying to do(?)
Just some ideas, hope that helps a little.
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What is the actual effect of surface wettability on bubble generation and bubble dynamics during pool boiling as the explanation and reasons provided by the researchers are not consistent?
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Hello,
This is a good question and a very difficult problem. To my knowledge, the subject is not (at all) totally closed.
Some interesting papers on the subject are (the first one is very interesting):
Surface wettability control by nanocoating: The effects on pool boiling heat transfer and nucleation mechanism, Hai Trieu Phan, Nadia Caney, Philippe Marty, Stéphane Colasson, Jérôme Gavillet, IJHMT
Augmentation of nucleate boiling heat transfer and critical heat flux using nanoparticle thin-film coatings, Eric Forrest, Erik Williamson, Jacopo Buongiorno, Lin-Wen Hu, Michael Rubner, Robert Cohen, IJHMT
Influence of the Wettability on the Boiling Onset,  B. Bourdon, R. Rioboo, M. Marengo, E. Gosselin, and J. De Coninck, Langmuir
Hope, it could help you,
Sincerely,
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I am trying to find bubble rise velocity in flotation. There are two approaches used in the literature:
1) Treat it as a particle surrounded by the liquid and find bubble velocity as
f(db, rhof, rhob, mu),
where, db is bubble dimater, rhof is fluid density, rhob is bubble density and mu is the fluid viscocity. 
2) Other method treats bubble rise velocity same as the rms velocity of bubble that is also function of density of particles and Energy dissipitation alongwith other variables in the previous method.
Does the bubble velocity also depend on Energy density?
Is it same as rms velocity?
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If the flow is non-turbulent  then the first approach is adequate. Otherwise. it is essential to consider the energy dessipation function while evaluating the bubble rise velocity.
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Is there any topological applications in the field of bubble dynamics?
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yes minimal surfaces and package of spheress
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Hi every one !
While using CFD codes ( Fluent 16 ) what should be the best practice for the following ?
Suppose a vertical rectangular bubble column( 30*60*6 = X,Y,Z cm ) , Single inlet at bottom with dimension 3mm*1.5mm , Velocity at inlet supposed to 0.06 m/s.
1) Velocity Inlet Boundary Conditions.. And also the Wall conditions ?
2) What should be the outflow ? Pressure Out or Degassing ?
3) Population Balance Models, How to treat this models ? i.e, BINS(CLasses) , Exponent Rato, Minimun Dia of Air ? what should be the boundary values of bins fractions if Inlet air dia is supposed to 8mm.
4) In the momentum Equation, how many forces can we include for overall best phenomenon ? Added mass, Drag, Lift, Wall Lubrication, Turbulent Dispersion, Turbulent Interaction, Surface Tension ?
5) For INITIALIZE... what should be the important changes ?
There are so many other factors that any expert can suggest to emphasis. 
Please suggest..
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Thank you Doctor,
Ricardo Vicente de Paula Rezende,
I am reading these papers....
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Hi every one,
there are many researches mentioned the Acoustic Doppler Velocimeter (ADV) to measure flow velocities 3D in open channel, but these papers did not mentioned the characteristics of bubble generator. what is the material that used to make bubble generator? I wonder if any one use ADV just give me some details of bubble generator.
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sorry about that, in water flow, one of apparatuses used to measure flow velocity is (Acoustic Doppler Velocimeter) ADV. to collect data, it is needed either seeding the water with a special material like sand or other moved with velocity same water flow velocity. these material reflect the wave sound from transmitter of ADV and received again by ADV and hence measured the flow velocity. now I use micro-bubbles to reflect the sound from ADV. to create these bubble I need a secondary tool to generate bubble. in my case I use two frames one for anode and second for cathode based on separation of water molecules. I need some one used ADV to let me know what he/she used to reflect the sound.   
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How to estimated the harding mechanism by the pressurized-Ar filled bubbles in the porous glass?  The results show the porous glass with ~20% porosity has high strength than that of dense glass matrix.
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In case you are concerned at the theoretical link between pore pressure and the 'effective stress' of the porous body, the following reference, although devoted to generic geological materials rather than porous glass, may possibly be found of some interest: R.O. Davis, "Pore pressure effects on interface behavior", in: A.P.S. Selvadurai, M.J. Boulon (Eds.), "Mechanics of Geomaterials Interfaces", Studies in Applied Mechanics: Nº 42, Elsevier, 1995; pp. 449-461.
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Hi Colleagues,
When it done image processing via high speed camera in air-water flow is, which points are important? and what do you suggest? 
For analysis, how many does a bubble divide pixels at least? or should it just only bubbly flow? Is slug or plug flow possible?
I am planning in a 50 cm as length and 4 cm as diameter channel. Is wall thickness important? Mein is 5mm. Will it for the camera hardly?
Best regards.
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Hi,
it depends, at least, on your image processing technique, typical bubble size, and local flow velocity.
In case of particle image velocimetry (PIV), image pairs are divided into patches. The size of the pixel patch is determined by the magnitude of the expected incremental particle displacement between the two images. Your flow should generate enough texture on the patches, so that PIV is able to track this texture between images. If camera resolution is poor or the images of bubbles or particles seeded in the flow are too small (say, less than 1 or 2 pixel), there might be no characteristic texture (= intensity matrix) for tracking. On the other hand, if bubbles were large or if your flow contains large-scale interfaces (e.g. slug flow), then you might track the interface directly using PIV.
Concerning PIV and two-phase flow, I recommend the following papers:
[1] R. J. Adrian: Particle-Imaging Techniques for Experimental Fluid Mechanics. Annual Review of Fluid Mechanics 23:261-304, 1991
[2] R. J. Adrian: Twenty years of particle image velocimetry. Experiments in Fluids 39:159-169, 2005
[3] R. Lindken, W. Merzkirch: A novel PIV technique for measurements in multiphase flows and its application to two-phase bubbly flows. Experiments in Fluids 33:814-825, 2002
Regards
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What are new methods, specially analytic methods that deal with non-spherical bubble dynamics?
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Dear Khaled,
The following text describes most methods dealing with non-spherical bubble dynamics.
Experiments of Rayleigh collapse have involved the use of a spark discharge (Kling & Hammitt 1972; Tomita & Shima 1986) or a laser (Lauterborn & Bolle 1975; Vogel, Lauterborn & Timm 1989) to vaporize a small volume of liquid, thus generating a cavitation bubble. Recently, high-speed photography has allowed detailed observations of cavitation bubble collapse near solid surfaces, including visualizations of the re-entrant jet formation and shock emission (Philipp & Lauterborn 1998; Lindau & Lauterborn 2003). Experimental investigations of shock-induced collapse also show the formation of a re-entrant jet in the direction of shock propagation and the emission of a shock wave upon collapse (Shima, Tomita & Takahashi 1984; Ohl & Ikink 2003; Sankin et al. 2005).
In addition, numerical simulations have therefore emerged as an alternative tool to complement the analysis and experiments. For more details, see the link indicated in the bottom of this answer.
Kling CL, Hammitt FG. A photographic study of spark-induced cavitation bubble collapse. Trans ASME D: J Basic Engng. 1972;94:825–833.
Tomita Y, Shima A. Mechanisms of impulsive pressure generation and damage pit formation by bubble collapse. J Fluid Mech. 1986;169:535–564.
Lauterborn W, Bolle H. Experimental investigations of cavitation-bubble collapse in the neighbourhood of a solid boundary. J Fluid Mech. 1975;72:391–399.
Vogel A, Lauterborn W, Timm R. Acoustic transient generation by laser-produced cavitation bubbles near solid boundaries. J Acoust Soc Am. 1988;84:719–731.
Philipp A, Lauterborn W. Cavitation erosion by single laser-produced bubbles. J Fluid Mech. 1998;361:75–116.
Lindau O, Lauterborn W. Cinematographic observation of the collapse and rebound of a laser-produced cavitation bubble near a wall. J Fluid Mech. 2003;479:327–348.
Shima A, Tomita Y, Takahashi K. The collapse of a gas bubble near a solid wall by a shock wave and the induced impulsive pressure. Proc Inst Mech Engng. 1984;198C:81–86.
Ohl CD, Ikink R. Shock-wave-induced jetting of micron-size bubbles. Phys Rev Lett. 2003;90:1–4.
Sankin GN, Simmons WN, Zhu SL, Zhong P. Shock wave interaction with laser-generated single bubbles. Phys Rev Lett. 2005;95:034501.
Hoping this will be helpful,
Rafik
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What are the analytical methods that can solve Rayleigh-Plesset equation in bubble dynamics field?
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Dear Sir. Regarding your question about the analytical methods that can solve Rayleigh-Plesset equation in bubble dynamics field. Several canonical results in bubble dynamics, including the Rayleigh collapse time, the Rayleigh-Plesset equation, and the Minnaert frequency have been re-derived. in arbitrary dimension. The bubbles generally display faster dynamics in higher dimensions, as the natural period and collapse time both decrease. Particularly, the late-time collapse behavior of a bubble is much stronger in higher dimensions. The normalized collapse equation and its analytic approximation were examined in higher dimensions, suggesting a choice of boundary conditions upon which to base the approximations. For more details the following below links may help you in your analysis:
Thanks
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Is there any study about lifetime of the bubble in nano-, micro- and macro-scale?
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This book may answer you a bit (not 100% sure): Please have a look.
Microscale and Nanoscale Heat Transfer: Analysis, Design, and Application.
Mourad Rebay, Sadik Kakaç, Renato M. Cotta
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Is there any applications of conformal mapping in fluid dynamics or precisely in the field of bubble dynamics?
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Sure, but you need the system to be quasi-2d, e.g. a Hele-Shaw cell. Check out the recent paper by Giovanni Vasconcelos:
"Multiple bubbles and fingers in a Hele-Shaw channel: complete set of steady solutions"
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Dear colleagues,
What are the current open problems on bubble dynamics research, especially in the field of biological applications. Growth, collapse, ... etc.
Best Regards
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An interesting area is how multiple bubbles are interacting with a tissue and cause fragmentation/liquification. For example in histotripsy the concerted action of cavitation fragment tissue. How bubbles achieve this is an open question and has relevance for the application in tumour therapy. 
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I want to study the motion of the single gas bubble in a stagnant liquid column, experimentally. Therefor I need to create single bubble. How can I create single gas bubbles? When I try to create just single bubble using syringe, it is produced multiple bubbles. How can I control the syringe to create only one bubble?
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Hi Amin,
You can refer to the classic paper 'On musical airbubbles and the sounds of
running water' by Dr.M.Minnaert. There is a detailed description on the apparatus used. You can slightly modify the set up to suit your test facility.
Here is the link,
Please let me know if you cannot access this paper. I can send it to your mail.
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Bubble dynamics research has many difficulties due to nonlinearity of the system of differential equations, so can we overcome on this difficulties by complex analysis techniques?
I wait for any contribution, paper, book, ... etc.
Best Regards.
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Va multumesc mult domnule Profesor.
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i am working i\on bubble column reactor, i need to calculate bubble diameter for some purpose.
so how do i need to calculate it
what are the different equations that are to be taken into consideration, 
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Greetings,
This paper may help you, with best luck.
Measurement of gas holdups and sauter mean bubble diameters in bubble column reactors by dynamics gas disengagement method
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Dear colleagues,
Kindly, Is there any mathematical manipulation to the problem of collapsing gas bubble in vivo? specially after decompression? this may be helpful to reduce the harmful effects of decompression sickness.
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I am not sure but I think there is an old paper by J.J.L. Velazquez. 
He is a mathematicians at the Haussdorff centre for mathematics.
I am not really sure he can explain the high temperature of a 
collapsing bubble (up to the point that it emits light). The problem is
interesting, please let me know what you will eventually find
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Dear all,
Kindly, Is there any earlier study on: Using Lagrangian mechanics to solve problems on bubble dynamics?
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A lot. As an example, you can start from this paper: http://scitation.aip.org/content/asa/journal/jasa/121/2/10.1121/1.2404798
From there you can check their references and articles citing this publication.
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The huge soap bubbles used for children's amusement are fascinating forms ! They last for many minutes in open air. The composition I am told is water, dishwashing liquid and guar gum or high fructose corn syrup. Can PEG or PVA or other water soluble polymers be used to stabilize a soap bubble ? What would be the best combination and recipe. Interesting experiments may be done with stable soap bubbles !
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To my understanding additives like PEG or glycerol can increase the viscosity of the fluid and in this way slow down the thinning process of the soap film. Also in soap solutions often micrometer sized glass beads are added. They act as "spacers" that prevent thinning of the soap film, and thus increase stability.
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Dear colleagues:
What are the basic equations that can be coupled to momentum, mass, ... etc equations in cases of the effect of electric and magnetic fields on bubble dynamics?
I wait your answers, and suggestions of earlier studies and articles.
Best Regards.
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Dear Esmaeel, Steffen and Hassan,
   Thank you for your valuable answers.
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Dear colleagues:
Is there a conformal mapping that transforms non-spherical surfaces to spherical ones? or what is the methodology to construct that mapping?  
if there is such mapping it's better to be convertible one.
Best Regards.
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Dear  Khaled Mohamed,
Suppose S is a compact metric surface, then  for each point p, there
exits a local coordinate chart (U,f ), such that p belongs U and the
local coordinates are isothermal  ( and metric conformal in local coordinates ) . In particular,   it is true for surfaces  in Euclidean  3-dimensional space.
Ahlfors, Lars V. (1966), Lectures on quasiconformal mappings, Van Nostrand
So using  Beltrami  equation, we can   local coordinates  in which metric is conformal.
best,
MM
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recently, nano bubbles applications are so interesting. What are the basic equations of nano bubble dynamics? and what are its current research problems? finally, if there are basic articles or text books talk about that topic, I'll be glad to read your answers? 
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You may consider the use of mathematical framework of porous media. I am quite sure that such framework is consistent with the suggestions of Dr. Dudley Benton. Nuclear magnetic resonance may add some nice dimensions to your research in this area. The following materials could be of help.
1. Micro- and Nanobubbles: Fundamentals and Applications by Hideki Tsuge
2. Subsurface Transport Behavior of Micro-Nano Bubbles
and Potential Applications for Groundwater Remediation
3. Monodispersed Nano-Bubbles Generated from Porous Glass Membrane and Bubble Size Control
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Does anybody know where to find data for validation of RPeq code. Sure, one can find many results in the papers, but nobody lists the values of ALL variables which are need to be included in the code (pressure evolution, initial bubble radius, surface tension, vapor pressure, liquid and vapor density, polytropic constant, viscosity... ).
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You can find such data in Table 1 of this paper:
S. A. Mohammadein and K. G. Mohamed, Growth of a gas bubble in a supersaturated and slightly compressible liquid at low Mach number, Heat and mass transfer 47 (12), 1621-1628, (2011)
I can also help you to find any missed data.
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After death, some in vivo  gases accumulate and grow in the body of died human or animals. Is there any study about gas bubble dynamics in that topic?   
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I don't know, but Dr. William M. Bass is the expert and his "lab" is right near here. Include him in your search.
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I need details with figure
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You can put the following keyword search sentence in search engine ( for example, google.com or scholar.google.com) you can find several papers talk about your topic which may have the answer or at least explanation for your question.
buoyancy force, bubble, increase, heat transfer, pulsating heat pipe
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I am wondering if velocity in formula means average velocity of fluid passing through cavitator, or velocity of fluid within the cavitator, between points with different pressure?
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There are many cavitation numbers depending on the purpose of research. If you want to define the incipient or end of cavitation, or cavitation threshold, or supercavitation, initial cavitation erosion or etc. and want to use data from previous studies, it is important to use the same cavitation number and to read the definition where the pressure difference and the speed is taken. In most cases you have to trust the selected cavitation number. Sometimes based on the experimental data (if published), it can make interesting conclusions or change cavitation number and propose new criteria.
If you're doing research perhaps for ultrasonic cavitator you should know the pressure distribution and choose correct place for measurements of the pressure difference and the velocity.
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Dear all
I am facing a problem related to non-dimensioning bubbble rising process in a quiescent medium. Almost all papers have described only two parameter ( Morton and Evotos number) which describes the process. However, the way I non-dimensionalize the Navier-Stokes equation, I get 3 non-dimensional numbers viz. Reynolds number, Froude number and Weber number, all sitting in the denominator of diffusive fluxes, gravitational body force term and surface tension term respectively. Now how to get these 3 numbers out of two given numbers(Morton and Evotos)?
Otherwise, please suggest the other method by which we can get only these two numbers, sitting in the Navier-Stokes equation.
Any sort of help is highly appreciated.
Jai
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The motion of a bubble is described by three dimensionless parameters, usually the combination Reynolds, Evotos and Morton. The most famous graph in the field is proposed by Grace, and  is in attachment.
To learn how to get the relations between the different numbers, you can use the exponent matching method, knowing that every dimensionless number can be described as a combination of the other three.
Take paper and pen and follow me with an example, on which I will surely make some arithmetic mistakes: we want to write the Reynolds number in terms of We, Eo and Mo.
By definition, the Reynolds is:
Re= d^1 U^1 nu^-1
While the We, Eo and Mo are:
We=rho^1 U^2 d ^1 sigma^-1;  Eo= d^2 rho g sigma^-1; Mo= g nu^4 rho^3 sigma^3
Thus we will write:
Re=We^a Eo^b Mo^c
On the left side we will have:
 rho ^(a+b+3c)* U^(2a)* d^(a+2b)*sigma^(-a-b-3c)*g^(c+b)*nu^(4c)
Now we can match the exponents, and we do it from the easy ones: those that have only one coefficient. From the exponent of U it is evident that a=1/2 and the exponent of nu gives us c=-1/4. We can now get the last from the sigma, for instance, noticing that b=1/4, and then double check that the rho will also hold: 1/2+1/4-3/4=0.
Provided that I made no mistake (please tell me in case :D), we are done:
Re=We^1/2*Eo^1/4*Mo^-1/4
Now that you've learned how it works, you can go for any other combination!
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I need to find the laminar bubble separation location on airfoils analyzed using XFOIL. Can anybody please suggest me how to find it?
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thank you Mr.Amir. Do you have any idea about  alternative method to identify the separation point?
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Hi
I am solving the Gilmore bubble dynamics equation for liquid sodium.  Tait's equation is used to relate pressure and density while solving the equation.  In the case of water the constant in Tait's equation is 3000 and the exponent 7.  Are there similar values for other liquids eg. liquid sodium ?
Thanks
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I also am wondering Tait parameters of other compressibility state equation for lead-lithium, for studying shock waves at 80 bar in a loop at initial 5 bar. I think I will try to deduce the parameters fitting the density equations reported by Schultz 1991 and by Hadbook of lead and lead bismuth eutectic, 2007
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The bubble dynamics are visualize using high speed camera and led lighting. Is there  a better way to visualize bubble ? 
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It is very difficult to visualize the incipience of the bubble, its growth and the departure.  This is because the duration of these activities is very small in the time scale. Certain mathematical modelling has been undertaken by Prof.V.K.Dhir and his group.  You may refer to their works.  
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I'm considering heating and vacuuming a solution to decrease dissolved gases as well as coating with a superhydrophobic material. Any ideas?
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DMEM = Dulbecco's Modified Eagle Medium ? first time i hear about it, it is out from  my field of expertise, I don't know if standard degasing methods used for physical research (boiling, vacuum , ultrasonic,) may destroy  your medium.
if your problem is the oxigen, then work with a different gas (Nitroge, elium..)
If you don't want any gas, you could connect your device to a vaccum pump and to the bottlle of your medium. all connections controlled by valves. First vacuum youir device, may be also yout bottle, then let your fluid flow from the bottel to the device. Take care your fluid do not flow into the vaccum pump (it could destroy it). 
Apart these general ideas, the details pof your necessity remain still quite unknown to me.
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I am looking for best and easiest software for a beginner in this field.
I am working with electroflotation column and I had a lot of hydrodynamic experimental results, now I need to validate them with CFD simulation.
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If you know your bubble size at time t=0, then it is easy to simulate the detachment and subsequent rise process using FLUENT. However, if you would like to simulate bubble growth on the electrode, it is not straightforward. Bubble growth rate kinetics must be separately coupled through a user defined function to FLUENT.
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Let's say we made an experiment with 2 cavitation bubbles. One is very big and the other is very small. They both collapse near a wall in a form of a microjet (nonspherically). Now we want to make a simulation and we are lazy and simply take the Rayleigh-Plesset equation for the spherical bubble dynamics. For the comparison to the experiment we measure the real bubble volume and recalculate how big the radius would be if the bubble would be spherical. Now the big question... which bubble would follow the prediction by the Rayleigh-Plesset equation more closely - the big one or the small one, and why?
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Dear Matevz, late answer, just joined RG.
The volume dynamics is very well captured with RP, thus RP should work for midly deformed bubbles. This is the case for gamma>1.5 near a surface, the jet forms only in the late phase prior collapse. The rebound with jet can't be captured with RP, because you loose energy during the impact (water hammer pressure) and the formation of a vortex ring. Thus the question remains, RP better for smaller than larger bubbles? It works very well for small (SL type bubbles) and for large ones (under water explosions), yet when the bubble is too large, buoyant effects can came in as the pressure head between top and bottom is large and the oscillation time is larger, thus more time to develop instabilities. My guess therefore is that RP is good for volume dynamics for gamma>1.5 and sufficiently small bubbles.
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Hi friends
I'm trying to model inflation of a rectangular sheet in abaqus for thermoforming process (Free forming). Material behavior is viscoelastic and I wrote a user subroutine for it. My problem is with the boundary condition in shell element, I don't know exactly how to model and constrain clamp region in abaqus. Has anyone modeled bubble inflation in Abaqus or any other FEM software?
Any help appreciated
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Thanks so much my friend for your valuable information.
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The pair of electron-positron have been produced in the pair production process.
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They are identical, the direction is mirrored.
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We are testing frying oil under vacuum and seeing it bubbling. The oil is only at about 138C and under about 22 in Hg (on the gauge) and we are exhibiting bubbling similar to a boil. Oil should not boil before reaching its smoke point, so we are unsure why this is happening. Can anyone help explain what is going on? 
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Soy oil is a mix of vaste numbers of different glycerid triesthers and unsaturated fatty acids. This mixtures usually have not a certain boiling point, but a range of boiling points of the different contents (azeotrope). You are experiencing the lower temperature boiling point of one of the contents.
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A mix of self-compacting concrete with remarkable fluidity and without segregation shows a strong accumulation of bubbles on the surface. This accumulation creates a layer of highly porous concrete and not resistant.
The concrete under this surface doesn't show high porosity.
Has anyone had the same problem? Could this be due to excessive kneading times?
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Thank you very much for your answers.
Indeed, it appears that it is due to an excess of the combination of additive and water. Without additive there is no segregation but it isn't enought fluid. Adding additive we have achieved the desired fluidity but we have not reduced the amount of water. We have avoid this problemn by adding more additive while reducing the amount of water while maintaining the right consistency for self-compacting concrete.
Thanks again.
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I'm wondering if there is any research work which has already aimed to measure the gas content of cavitation bubbles occurring inside nozzles (geometrical induced cavitation) ? 
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Hi again,
A cavitation bubble normaly consists of combination of dissolved gas (O2, N2 etc..) and vapour. (For further explanation, you can look at 1st and 2nd chapters of Brennen's book 1995)
Mostly, i am interested in the numerical simulation of cavitation based on bubble dynamics models. Therefore, i could say that, due to easy treatment, most of cavitation models based on bubble dynamics ignores the dissolved gas and assumes only vapour inside of cavitating bubbles. Thats, why physically we assume that when the pressure in the local region falls below the Pv (vaporisation pressure) bubbles (which are already existed inside liquid) start to grow up. This phenomena is called as cavitation. In other words, the small micro bubbles are already dispersed inside liquid, which result in the phase change by growing up within low pressure region.
Hope it helps for you.
Baris. 
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Are there any analytical equations or theories that relate the final droplet's SMD to the mechanism by which cavitation bubbles improve the spray emerging from plain orifice nozzles into still air?
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I complete Mr Bicer's answer : the bubble collapse is due to inertial phenomena and lead sometimes to implosion which results in the splitting of the main bubble in various smaller ones tha t can have the size of a spray particle.
Regards!
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Bubbles form only when a charged particle enters in the bubble chamber. Some literature gave ionization as the reason for the bubble formation.
What is the basic mechanism? How does ionization cause a state change?
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If you know the heterogeneous nucleation theory of  phase transformation, the answer is ready.  In the bubble  chamber we have super saturated vapor, the condensation means the formation of an interfaces between the condensate. That means there is positive contribution to the Gibbs free energy proportional to the area of the  interface, which roughly linear function of radius R of the droplet. On the other hand bulk Gibbs free energy  of condensation, which is negative for the  supersaturated vapor varies with the third power of  R.  This results an activation energy barrier for the  formation of quasi-stable  droplet  (embryo)  having a critical radius above which it grows and below which it shrinks.
 When the condensation takes place  through thermal energy fluctuations on any foreign objects (such container's walls, etc.), one has to consider two newly arised  free energy terms, namely;   the free energy associated with formation of an additional interface between embryo and  foreign object (i.e., substrate).  secondly,  the replacement of the interface energy between the foreign particle and vapor  by the free energy  between the droplet versus vapor phase.  The global surface free energy balance  might be positive or negative (depends on the interface free energies , whether one has wetting or not).  If it is positive,  the activation barrier increases and the heterogeneous condensation  doesn't   take place. If its negative (less surface free energy) the condensation preferentially takes place around foreign particles here charge particles.The quantitative treatment can easily be formulated. 
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I am making styrene disk through bulk polymerization with some organic added to the monomer. I am polymerizing the monomer in a closed container at 80  C but getting some bubble which is affecting my final product.
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There are two possibilities, dissolved gas or too high temperature. In the first case try to remove dissolved gaseous impurities at decreased pressure just before polymerization. Other possibility, if the temperature inside Your disc is too high to styrene or organic stuff boils, try to perform polymerization at lower temperature. What type of initiator do You use? May be try to add less. Start polymerization at lower temperature. If You use peroxide, they will form radicals at much lower temperature when some tertiary amine is present, or try ionic initiators…
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I am working on Bubble column of inner dia 16 cm of completely transparent glass.
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If you are solving multiphase  problem  and you have taken bubble as air or vapor (whichever your project deals ) then in multiphase flow -mixture  option , you will get secondary phase option ,edit it . there will be option in properties that you can specify diameter of bubble, If I am not wrong , PLEASE SEE ATTACHMENT 
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What are the effects higher turbulence on laminar separation bubble ?
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I think higher turbulence causes the laminar separtion bubble to shorten. Also higher turbulence would caouse the separation point to go further downstream. It would kind of look like you have tripped the flow from the leading edge.
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If the fluid is liquid air, why will the cavitation be different from single component cavitation like liquid nitrogen or hydrogen?
How can we simulate this kind of cavitation? The manual of commercial software "FLUENT" have said that "FLUENT" cannot be used when there are more than one component cavitating.
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In this case you have 4 components: liquid nitrogen, vapor nitrogen, liquid oxygen and vapour oxygen. For every pair (liquid-vapour) you must define in Fluent an UDF (only one for every pair). It may works.
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I am looking for a simple experimental method to calculate bubble film thickness of an individual soap bubble.
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Interferometry is a fast and reliable method for measuring thickness of thin films that could be applied to bubbles. Note that the film thickness in bobbles changes as function of time. So you may need a real-time technique. I am not sure how fast interferometry can be, but there are real time interferometry systems available and surely it is rather simple (and is contact free) approach.
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I have carried out the experiment and have the recorded images of the bubble train but do not know how to go about analysing them. Thanks
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We use Boundary element method. See my papers in Journal of Fluid Mechanics, Journal of Computational Physics. You might also look at the Lab on a Chip paper (Smith and Gaver).
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An antibubble is similar to a bubble but the air envelops the liquid, not the other way around.
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The antibibble lifetime is driven by the slow drainage of the air from the bottom to the top of the antibibble. This confined flow is affectee by the boundary conditions, i.e. The interface air-liquid. More precisely, one must take into account the viscosity (shear and dilatationnal) of the interface. These physical properties are related to the chemical properties of the surfactant molecules used to make the antibubbles. More viscous, longer lifetime...
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This is to help understand the rate of change of bubble growth in aqueous solution
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A classical analysis of bubble growth in nucleate boiling of pure materials and binary mixtures is given by L.E. Scriven, Chemical Engineering Science 10,1, 1959. This is a Science Citation Classic paper and thus you can readily find new developments in the analysis of this important problem. In this paper the physics of the phenomenon and the appropriate assumptions are made clear.