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Modelling two-phase flow(slug, stratified, bubbly)

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Old   March 20, 2008, 14:12
Default Modelling two-phase flow(slug, stratified, bubbly)
  #1
Renato Pacheco
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Hi. I have to model these 3 diferente two-phased flows and I would like you to help me.

Im using unsteady solver, VOF, K-omega, and the two phase are water-air. I put a velocity inlet on the BC with 1m/s and 0.5 for the water volume. on the solution controls i put piso. i am using time step of 1e-4 and im getting converged solution, but i can not see a slug flow(such as on the books), forming on my contours displlay.

anyone can help me?
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Old   March 24, 2008, 12:31
Default Re: Modelling two-phase flow(slug, stratified, bub
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Renato Pacheco
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no one can help me???
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Old   March 24, 2008, 15:47
Default Re: Modelling two-phase flow(slug, stratified, bub
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Dave S
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This is not what the VOF model was designed for. With slug flow you will have interdispersed phases and in the model there will be a change in the flow regime so you should use the full Eulerian M/F model. I have used this for exactly what you are doing and it works well.
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Old   March 25, 2008, 01:04
Default Re: Modelling two-phase flow(slug, stratified, bub
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Renato Pacheco
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but I saw a journal where the writer could do it with VOF.. anyway, i will try tomorrow with M/F model... when I try it, can u help me?? can I send email directly to you?
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Old   March 25, 2008, 03:22
Default Re: Modelling two-phase flow(slug, stratified, bub
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Dave S
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No problems with that.
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Old   March 27, 2008, 10:00
Default Re: Modelling two-phase flow(slug, stratified, bub
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Shin
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I am trying to simulate Taylor flows in a capillary these days. I have used unsteady VOF with other settings similar to what you mentioned. Did you give proper values to surface tension and wall adhesion? Also, volume fraction method in solution controls window is important for the sharpness of interfaces. How many cells are you using?
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Old   March 27, 2008, 12:18
Default Re: Modelling two-phase flow(slug, stratified, bub
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Renato Pacheco
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hmmm i have no values for wall adhesion, but i've put the value of surface tension for water. when i put this value of surface tension, the bubbles started to form. it seems quite good now. im only having problems with turbulence viscosity ration. its giving me a warning msg.
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Old   March 27, 2008, 12:28
Default Re: Modelling two-phase flow(slug, stratified, bub
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Shin
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Wall adhesion sometimes effects bubble shapes so I think you need to check it out later. Warning messages do not matter. Anyway congratulations that you got what you want.
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Old   March 27, 2008, 13:45
Default Re: Modelling two-phase flow(slug, stratified, bub
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Renato Pacheco
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ok.. thanks for your help.
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Old   March 28, 2008, 12:41
Default Re: Modelling two-phase flow(slug, stratified, bub
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Renato Pacheco
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just one more question.. when using this kind of problem, do you use BC at the outlet as an outflow or pressure autlet?
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