[sambayo]

hi,

i still cant get the point how to draw a line ,should i choose select with the mouse or should i enter the points depending on what

never mind about the second question ,,

[sambayo]

hey

can you please tell me when your back i need some more help ?

Hope you enjoyed your vacation

Thanks

[sambayo]

heeey,

how to determine the flow Regime ?

[thecfduser]

Hi
i am back
what is ure question?? u need to determine the flow regime from the flow rates???

[sambayo]

heeey how r u ? hope you enjoyed ur holiday and welcome back

my question now i am making the pipeline diameter 1 inch with a length of 5 meters but the boundary conditions are still trial and error
when ploting the contor plots i always plot at t=0.000 but when looking to some tutorials i found out that they are plotted at diffrent times so how could i do so ?

do u suggest any flow inlet velocity for mixture of air and water to show the flow regimes clearly ?

thank you so much and welcome back

[Hoper]

Hi guys! I am also working on multiphase flow in pipes, with emphasis on laminar flow. Can I know what the problem is, so I can help out?

[Hoper]

Hi Sambayo,

If I get you right, the problem revolves around defining line/rake on which to base the plot. To accomplish this purpose, you have to accurately know how the pipe is oriented with respect to your chosen reference coordinates.

Can you explain the orientation of the pipe or post a picture for us to see, and also state clearly what direction you want to base the plot? Thay way, I can give you procedures of how to go about defining the line/rake.

Cheers!

[thecfduser]

Hi
yes my holidays was good but too long
i hope that u enjoyed ure time too
If u are using a 1 inch diameter, i advice u to see the map of flox regimes made by taitel and duckler (1976). they did experiences on a 1 inch diameter and drawed a map of different multiphase regimes.
To plot contours on different times, i dont know if there is another method, but me, i would do an autosave of data files, than draw every plot...
For the velocity at the inlet, it will depend on the flow that u want to simulate. To see clearly different regimes, it will depend on ure turbulence model.....If u are not using DNS or LES, i advise u to simulate half the pipe with a symetry condition, so u can save time...
Hope to hear soon from u

[Hoper]

Hi thecfduser,

Do you have any idea about defining regions in FLUENT? I have been trying to model a piston-like displacement of one fluid phase by another in a pipe, but I don't seem to have a good handle of the "region definition."

I'd appreciate you help.

[thecfduser]

Hello hoper
welcome to our discussion
Simulating laminar multiphase flow in pipes is not so much complex since we can do a DNS. The problem arises from the turbulence in such flows: they are much more unstable than monopphase flow, because of the interface presence....
So we are discussing about modeling different multiphase regimes in pipes (slugs, stratified, annular...) and wich turbulence model can be the most suitable....
Theortically, it will be the RMS model with near wall treatement since it allows the siulation of anisotropic secondary flow....In practice, the Istotropic k-eps model can handlle this too (a bit strange...)
Glad to share the discussion with u

[thecfduser]

U must do it in Gambit. U can define different regions. In fluent u can do it too but i have never tried it.
I will try to take a look to it (u can search on fluent user's manual)

[Hoper]

I've been trying to define regions using FLUENT, but no success. I may have to try the GAMBIT option. Thanks a lot.

However, GAMBIT isn't working on my 64-bit win vista. It seems Exceed2006 isn't compatible with vista. Do you know a way around this?

[sambayo]

heeey ,

i would really appreciate if you help
i have an like a project to do which is to model a multiphase flow air and water in a pipe but i am facing difficulties in the 3D model ?

i dont have specific conditions which means that i don't have a specific pipeline length or diameter and the velocity of the flow i enter whatever i want ?

but when making the 3D drawings after solving i dont know how to plot my results to make the analysis i have noticed that contour plots are at different time but all i can draw is at t=0 so how i find any contor at t=2 for example .have

my assumptions now

pipeline 5 m
pipeline diamter 1 inch

if u have a solved problem that u know that can help me to learn that would be awesome

[thecfduser]

Hi
i had a lot of problems with exceed and fluent on Vista
turn to Xp

[sambayo]

heeey,

thanks for replying but i dont know does vista really affects the result ? what kind of problems could appear

do u know how to make contours plots at different times

[bugra]

hi there,

i have a question,
i'm trying to investigate water spray in air with vof model in fluent. the problem is 3d and i only want to know the dispersion of water (the distance it arrived ...etc). may be you can help me ?

[thecfduser]

Hi
i dont know this topic very very well but:
1-a big problem with VOF is artificial coalescence: in a cell u have 1 interface only, wich mens that if 2 droplets are close with a distance<cell size, VOF will coalesce them in 1 droplet.
2-In sprays, u have 2 regions: a first dense 1 wich VOF can used to model it. The second region is a dispersed spray and here VOF will not work good, unless u have a very fine mesh....
Try to ask someone that know the topic better than me
Hope that it was helpful

[bugra]

hi karine,

thank u, it's helpfull for me, nevertheless, i'm open to any other information about this problem

thanks...

[thecfduser]

No problem
If u tell me more about ure problem, maybe i can help.
Do u know a priori the granulometry (size distribution) of ure spary?

[CFDlearn]

hi all

i hope every one in this discussion is ok


thanks a lot thecfduser for your great help and valuable notes


i m also studying a problem (condensation of R-134a inside along tube )


my problem is 2d saturated vapor enters from inlet it become a saturated liquid at exit condensation is considered to be annular along the tube



i hope you can tell me the path that i can fellow to perform it