Questions related to Bubble Dynamics
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?
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
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 ?
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?
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?
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?
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
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?
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
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:
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
This also fails.
Hence I am unable to solve this. What to do in this case?
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.
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.
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?
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.
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?
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?
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?
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.
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.
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.
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?
Is there any applications of conformal mapping in fluid dynamics or precisely in the field of bubble dynamics?
What are the current open problems on bubble dynamics research, especially in the field of biological applications. Growth, collapse, ... etc.
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?
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.
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,
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.
Kindly, Is there any earlier study on: Using Lagrangian mechanics to solve problems on bubble dynamics?
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 !
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.
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.
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?
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... ).
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?
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?
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.
I need to find the laminar bubble separation location on airfoils analyzed using XFOIL. Can anybody please suggest me how to find it?
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 ?
The bubble dynamics are visualize using high speed camera and led lighting. Is there a better way to visualize bubble ?
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.
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?
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
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?
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?
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) ?
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?
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?
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.
I am working on Bubble column of inner dia 16 cm of completely transparent glass.
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.
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