I am simulating slug flow through a horizontal large diameter 0.08 m, pipe length is 15m, I have adpoted the VOF model with a 0.0737 constant surface tension. turbulence model.

BC: I split inlet to gas inlet and water inlet to set inlet velocity and hydraulic diameter respectively. Gas: 5 m/s 0.064m Liquid:2.5m/s 0.016m

BC for outlet is outflow.

IC: I set gas and liquid stratified flow.

12000 cells.

From the flow pattern map, the transition from stratified to slug flow should be seen from the result.But from my result ,it is always stratified wavy flow.

Anyone can give me some ideas.

Sincerely appreciate your kind assistance. Thanks in advance.

How do you "set" IC to be tratified flow? What parameters do you set exaactly?

im not sure this gas-liquid velocities are ok for slug formation. witch flow pattern map you are using?

im following mandhane pattern map, and i could get stratified-slug forming with gas velocity=2m/s and liquid=1m/s

i also used oulet as pressure autlet to avoid backflow formation. other thing u have to take care is the turbulence intensity...

and i think you model is too long and have very low number of cells. mine has 20000 cells but is 2 meters long and i think its also a low number of cells. if i had computer to run it i would put arround 400000 cells...

if you need some help, i have here the flow maps from baker, mandhane and taitel & dukler.

the parameters you set to be stratified flow or any other flow pattern, is the superficial velocity, according to some flow pattern maps. but you can never forget that any turbulence are not formed by their own. they need some perturbations, that could be a white noise on the inlet, a backflow on the way of the fluid flow... this you can set by turbulence intensity on fluent menus.

[giovanni.el]

Dear Justion,

I was just looking for a flow pattern map for a 0.08m ID pipe, when I came across your post. I couldn't find it, I was wondering if you could share it.

Regards,

Giovanni