CFD Online Discussion Forums

CFD Online Discussion Forums (
-   FLUENT (
-   -   Bubble Diameter (

Santi May 22, 2003 01:26

Bubble Diameter
Hi all, I try to simulate gas - liquid mixing in agitated tank. I'd like to compute the change of bubble diameters because of bubble coalescence and bubble break-up. I use multiphase model --> mixture model . For computing bubble diameter I use UDF. First, I define conservation equation for 'n' (bubble number/unit volume) as UDS. Because it is a multiphase model so I must define the flux term in UDS using DEFINE_UDS_FLUX, and the diffusivity term (dispersion coefficient) using DEFINE_DIFFUSIVITY. Finally I define bubble diameter using DEFINE_PROPERTY. All of these UDF access second phase domain, so I use phase_domain_index, or DOMAIN_ID, or thread_sub_thread. I have compiled my program, and FLUENT can read, so it is right according to FLUENT's syntax. But when I try to iterate, it was error. So what do you think? Do you have any idea?? Please help me. Thank you

Shiping Liu May 26, 2003 10:45

Re: Bubble Diameter
I am working on a project of liquid-liquid dispersive mixing, in which drops break up and coalesce. I also want to use Fluent simulate the drop size distribution, but its solver does not allow drop size change.

From your message, you want to combine breakup and coalescence models with flows. It is very good idea. It is, however, very tough to do. So far I have not found a case in publications. Most people suppose there is no interaction between two phases when they use breakup and coalescence models. Of course, those people have no capability of putting them together.

If you have any progress, please let me know. Good luck.

santi May 28, 2003 22:02

Re: Bubble Diameter
I'm working with gas-liquid mixing in a stirred tank. So I want to compute gas bubble's diameters. Your research is liquid-liquid flow, isn't it? If you want to compute the droplet size you can use Discrete Phase Modelling --> you can model droplet size/diameter, because there is a facility to model it in DPM. Good luck!

minnikanti March 4, 2010 11:56

hi santi im working on two phase gas liquid bubble flow and i have to account for bubble breakup and coalescence just like you can you elaborate a bit about your approach

All times are GMT -4. The time now is 03:49.