# Rise of a spherical bubble terminal velocity

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 June 4, 2008, 13:54 Update on the case. The veloc #21 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 11 Update on the case. The velocity gradient mentioned above was due to boundary influence. With a slightly bigger geometry the result is within 1.4 % error of the estimated value of the terminal velocity. risevelocity.pdf __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 June 6, 2008, 03:44 Hi Sebastian I have just fo #22 Senior Member   Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Rotterdam, The Netherlands Posts: 1,595 Rep Power: 24 Hi Sebastian I have just found a tool called sampleSurface, where you can extract isoSurfaces. Look in the template-dict in ~/OpenFOAM/OpenFOAM-1.4.1/applications/utilities/postProcessing/miscellaneous/sa mpleSurface. Have a nice weekend, Niels __________________ Please note that I do not use the Friend-feature, so do not be offended, if I do not accept a request.

 October 20, 2008, 14:32 Hi all, sebastian, thanks #23 New Member   Azman Join Date: Mar 2009 Location: Aachen, Germany Posts: 3 Rep Power: 8 Hi all, sebastian, thanks for sharing your case in this forum. at least I know now what to look out when simulating rising bubbles with InterFOAM. I have been playing around with the InterFOAM solver for about 2 weeks now, and was toying with the idea of solving the concentration field of oxygen bubble rising in water using InterFOAM. I am not sure whether you or anyone have ever tried it. The first strategy that came to my mind was ..just adding the scalarTransport equation (just like how it was defined in the ScalarTransportFoam) in my InterFoam solver, after the gamma equation and velocity equation is solved. solve ( fvm::ddt(C) + fvm::div(U, C) - fvm::laplacian(DT, C) ); with DT = gamma*D02_liquid + (1-gamma)*DO2_air I am however not sure how I can include a jump condition at the interface, such that CO2_liquidinterface = HenrysKoeff*C02_gasinterface. I fear that this is not possible with the VOF method since VOF doesnt track the interface per se, but just the vol. fraction of each cell, and magically reconstruct the interface. Am I right? I recently came across a paper from Bothe et al., about direct numerical simulation of mass transfer between rising bubbles and the surrounding liquid that can be accessed through the link below. http://chemie.uni-paderborn.de/fileadmin/chemie/Arbeitskreise/Warnecke/Literatur /bubblyflows.pdf In their work with a self-built fvm code, the VOF method was used too, with the PLIC method to reconstruct the interface. The scalar transport equation was solved as follows: Inside each phases: dC'/dt + div(C'*u) = DT.grad(C') whereby C' = C_liq at the liquid phase C' = C_gas/H at the gas phase DT (as above) at the interphase: C'_L = C'_G D02_liquid*grad(C').n = H*D02_Gas*grad(C').n Does anyone know what to include in the solver, such that the condition at the interphase is fulfilled.

 June 26, 2009, 07:19 #24 Senior Member   isabel Join Date: Apr 2009 Location: Spain Posts: 171 Rep Power: 8 How do you use fundySetFields? I want to define a spherical bubble of radio 0.001 and center 0,0 and I have typed: funkySetFields . . -field gamma -expression 0 -time 0 -keepPatches -condition "pow(pos().x,2) + pow(pos().y,2) < pow(0.001,2)" But I received this error: bash: funkySetFields: command not found

 June 26, 2009, 07:22 #25 Senior Member   Niels Gjoel Jacobsen Join Date: Mar 2009 Location: Rotterdam, The Netherlands Posts: 1,595 Rep Power: 24 Search this forum, and you will find the place, where it can be downloaded as an add-on to OF. Further you will find a thorough wiki on the subject. Best regards, Niels

 July 6, 2009, 08:11 #26 New Member   Brugiere Olivier Join Date: Mar 2009 Posts: 27 Rep Power: 8 Hi all, I have a bubble and I would like make the same graph than Sebastian. I have find the velocity 's maximun. But now I would like find the cell where this velocity is localise. Thank's for your help Olivier

July 6, 2009, 09:05
#27
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Sebastian Gatzka
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Quote:
 Originally Posted by brugiere_olivier Hi all, I have a bubble and I would like make the same graph than Sebastian. I have find the velocity 's maximun. But now I would like find the cell where this velocity is localise. Thank's for your help Olivier
I have chosen the center of of the bubble for my plots.
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 July 7, 2009, 02:25 #28 New Member   Brugiere Olivier Join Date: Mar 2009 Posts: 27 Rep Power: 8 Thank's to your help, but how do you find the center of the bubble ? Because I can't fetch your archive barycenter.zip

 March 3, 2010, 17:11 #29 Senior Member     Sebastian Gatzka Join Date: Mar 2009 Location: Frankfurt, Germany Posts: 729 Rep Power: 11 Oh, this has been far in the past. I was stumbling about your question just today. Unfortunately I can't fetch the file for myself and I have lost it due to some system error ... Can anyone post it again? __________________ Schrödingers wife: "What did you do to the cat? It's half dead!"

 March 4, 2010, 03:42 #30 Senior Member   isabel Join Date: Apr 2009 Location: Spain Posts: 171 Rep Power: 8 Hi sega, There is a paper in which is defined the rise velocity: "Thermocapillary motion of deformable drops and bubbles" by Hermann, Lopez, Brady and Raessi. In this paper, the equation (3.2) is used to compute the rise velocity of a bubble.

 January 30, 2011, 05:39 rising bubble #31 New Member   bita Join Date: Jan 2011 Posts: 2 Rep Power: 0 hi all i simulate rise of spherical bubble with interfoam,but i can't open cases in this forum,can anyone help me?

January 30, 2011, 06:10
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Quote:
 Originally Posted by bita.kh hi all i simulate rise of spherical bubble with interfoam,but i can't open cases in this forum,can anyone help me?
If by "Case" you mean "Thread", try to use the "New Thread" button.
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 September 27, 2011, 09:01 #33 Member   Duong A. Hoang Join Date: Apr 2009 Location: Delft, Netherlands Posts: 92 Rep Power: 8 Hi Sebastian, I saw in the first post that you used symmetryPlane with interFoam but you found some problems. Did you find ways to fix it? I am also facing problems with using symmetryPlane in interFoam as in my post http://www.cfd-online.com/Forums/openfoam-solving/92524-strange-pressure-behaviour-symmetricplane-boudary-condition-interfoam.html. I hope to hear your comments on this. Regards, Duong

 October 26, 2011, 13:39 numerical dispersion in OpenFoam #34 New Member   srikanth Join Date: May 2011 Posts: 2 Rep Power: 0 hi Sebastian, I am a student (new to OpenFoam) and am working on studying the rise behavior of bubbles in sheared liquids. I am using a 3D case without axial symmetry and am simulating flow in a linearly sheared rectangular column. Due to the large size of the column I am unable to use a mesh with a resolution greater than 10 cells per diameter. I am also facing the same problem of smearing in testcases as fine as 15 cell per diameter.Have you found a way of resolving this. P.S. I am also working in Fluent and the same mesh works perfectly without any smearing.Is this an advantage of PLIC over Interface compression ? In anticipation of your reply Regards

 November 1, 2011, 13:12 #35 Senior Member     Kyle Mooney Join Date: Jul 2009 Location: Amherst, MA USA - San Diego, CA USA Posts: 268 Rep Power: 9 There is a good comparison of the performance of various reconstruction methods here if your interested: Volume Tracking Methods for Interfacial Flow Calculations, Murray Rudman 1997. International journal for numerical methods in fluids. I'm guessing the PLIC is saving you from poor interface resolution in the Fluent cases. Unfortunately it's not currently implemented in OpenFOAM although I believe there are some people working on it for structured hex meshes.

November 19, 2011, 09:26
barycenter and drop rise velocity
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Quote:
 Originally Posted by sega Hello. I received a question about how I calculated the terminal velocity. I have used a post-processing tool I got from the university. I don't know in detail where it comes from, but it was really useful: barycenter.zip The tool calculates the location of the mass center of the phase gamma=0 at each timestep. I tun the tool over my case and put the results into a file named 'center'. barycenter . . >center Then I picked the times and positions of the masscenter and calculate the displacement over time which is representing the rising velocity. Greetings. S.
Hi Sebastian,

I am able to simulate drop rise velocity using interFoam solver. Then I ran barycenter utility as posted above successfully.
I am now stuck at how to extract the time and barycenter coordinate (say in .xy format)?
So that I can calculate instantaneous drop rise velocity over a time.

How did you pick the times and position of the masscenter from center file generated using barycenter utility?

Hrushikesh

January 7, 2012, 05:03
#37
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Sebastian Gatzka
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 Originally Posted by Hrushi Hi Sebastian, I am able to simulate drop rise velocity using interFoam solver. Then I ran barycenter utility as posted above successfully. I am now stuck at how to extract the time and barycenter coordinate (say in .xy format)? So that I can calculate instantaneous drop rise velocity over a time. How did you pick the times and position of the masscenter from center file generated using barycenter utility? Hrushikesh
Well I used
Code:
`barycenter > center`
to produce an output file "center", deleted everything i didn't want manually and imported the data with MATLAB ...
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 August 21, 2012, 10:53 Barycenter utility #38 New Member   Angelo J. Chaves Join Date: Aug 2012 Location: Itajubá, Brasil. Posts: 3 Rep Power: 4 Hello I am new here in the forum and I have been working with the same case of the bubble rising. I'm using interDyMFoam and an parallel processing to simulate the case. Now I want to calculate the barycenter of the bubble so I can get the velocity in each step of time. I downloaded the barycenter utility, but when I try to install it, an erro message occurs. ana@ana:~/OpenFOAM/OpenFOAM-2.1.0/applications/utilities/postProcessing/barycenter\$ wmake Making dependency list for source file barycenter.C could not open file readEnvironmentalProperties.H for source file barycenter.C SOURCE=barycenter.C ; g++ -m64 -Dlinux64 -DWM_DP -Wall -Wextra -Wno-unused-parameter -Wold-style-cast -Wnon-virtual-dtor -O3 -DNoRepository -ftemplate-depth-100 -I/home/ana/OpenFOAM/OpenFOAM-2.1.0/src/transportModels -I/home/ana/OpenFOAM/OpenFOAM-2.1.0/src/transportModels/incompressible/lnInclude -I/home/ana/OpenFOAM/OpenFOAM-2.1.0/src/transportModels/interfaceProperties/lnInclude -I/home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude -IlnInclude -I. -I/home/ana/OpenFOAM/OpenFOAM-2.1.0/src/OpenFOAM/lnInclude -I/home/ana/OpenFOAM/OpenFOAM-2.1.0/src/OSspecific/POSIX/lnInclude -fPIC -c \$SOURCE -o Make/linux64GccDPOpt/barycenter.o barycenter.C:49:44: error: readEnvironmentalProperties.H: Arquivo ou diretório não encontrado In file included from barycenter.C:52: createFields.H: In function ‘int main(int, char**)’: createFields.H:92: error: ‘g’ was not declared in this scope In file included from barycenter.C:55: /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/setInitialDeltaT.H:35: error: ‘CoNum’ was not declared in this scope /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:3: warning: unused variable ‘nOuterCorr’ /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:6: warning: unused variable ‘nCorr’ /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:12: warning: unused variable ‘momentumPredictor’ /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:15: warning: unused variable ‘transonic’ make: ** [Make/linux64GccDPOpt/barycenter.o] Erro 1 ana@ana:~/OpenFOAM/OpenFOAM-2.1.0/applications/utilities/postProcessing/barycenter\$ I'm also a new user of the linux system but I guess the erro occurs because I'm using an new version of the OpenFoam (2.1.0) instead the original one that the utility were made for. If anyone could help me, I would be grateful.

August 22, 2012, 01:09
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Quote:
 Originally Posted by A.J.Chaves barycenter.C:49:44: error: readEnvironmentalProperties.H: Arquivo ou diretório não encontrado In file included from barycenter.C:52: createFields.H: In function ‘int main(int, char**)’: createFields.H:92: error: ‘g’ was not declared in this scope In file included from barycenter.C:55: /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/setInitialDeltaT.H:35: error: ‘CoNum’ was not declared in this scope /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:3: warning: unused variable ‘nOuterCorr’ /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:6: warning: unused variable ‘nCorr’ /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:12: warning: unused variable ‘momentumPredictor’ /home/ana/OpenFOAM/OpenFOAM-2.1.0/src/finiteVolume/lnInclude/readPISOControls.H:15: warning: unused variable ‘transonic’ make: ** [Make/linux64GccDPOpt/barycenter.o] Erro 1 ana@ana:~/OpenFOAM/OpenFOAM-2.1.0/applications/utilities/postProcessing/barycenter\$ I'm also a new user of the linux system but I guess the erro occurs because I'm using an new version of the OpenFoam (2.1.0) instead the original one that the utility were made for. If anyone could help me, I would be grateful.
Hi Angelo,

Yes, you are right. You need to make some minor changes in that code. I had done it a year back. I will have to look into my old files. If I get it, I will upload it here asap.

September 21, 2012, 14:24
baryCenter
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Hi Angelo & Tayo

Here is the updated version of baryCenter baryCenter-of201.zip utility. I have tested it on OpenFoam-201. You can comapre the each file in zip archive with one that you have to recognise the changes one needs to make it usable in OF201.

Hope it helps.

Regards
Hrushi
Attached Files
 baryCenter-of201.zip (4.4 KB, 92 views)

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