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-   -   Flow around ship hull, multiphase setup!! (http://www.cfd-online.com/Forums/fluent/77336-flow-around-ship-hull-multiphase-setup.html)

alibul June 20, 2010 17:45

Flow around ship hull, multiphase setup!!
 
Hi everyone,

I am trying to find the flow characteristics around a ship hull by using Fluent. I did the model, I did the meshing in Gambit everything is fine until so far. It is a multiphase problem (air and water), I have two velocity inlets, hence two continuum volumes, hence two interior boundary conditions etc. I have two pressure outlets (when I imported the meshing in fluent, it divided my outlet into two since there are two continuums).

However I am having some difficulties in setting the problem in fluent. First of all, I am trying to use the VOF model. When I have two continuum like this, how do I set up the problem? How do I define free surface in this case. My aim is to get the drag coefficient, surface elevation and wave profile on the hull. I searched every thread in these forums but I could not get a solid answer for my case.

Do I have to write a UDF for VOF or is there any other way to get the results by using two phases like how I have done? Or should I start the problem with one continuum in Gambit and one inlet and then introduce it in fluent as a multiphase model? If so, then how to do it?

I seriously need some help. Thank you very much in advance. :)


Ali

jack1980 June 22, 2010 16:58

Hi,

What you could do is:

- Have a split water velocity inlet and air velocity inlet. You can set the volume fraction of the water inlet to 1 in the boundary conditions panel

- For all other boundaries you will not have to make a distinction for the phase. This means you can have a single wall boundary and a single pressure outlet (with udf)

Have a look at pages 62 - 65 of https://docs.google.com/fileview?id=...MjNkZGJl&hl=en

Another option is open channel flow

alibul June 23, 2010 19:30

That was what I needed.. Thank you very much for the info and for the document..

Hermanus Henning June 25, 2010 09:23

Good day everyone,
I'm new to the CFD world and I would just like to say hi!

Alibul, thank you for posting the question, I'm in the same "boat".
Jack, thank you for the advice to Alibul, its very useful:)

Regards

kabilan February 9, 2011 06:00

ship
 
hai,
i want to know which multiphase is suitable for ship analysis.
when i solve by using vof, unstructure mesh, the error occurs i.e) over spills.
pls rply (vof or euler or mixture.....)

Hermanus Henning February 9, 2011 07:40

Vof
 
Hello Kabilan,
I used the vof method because I'm moddeling a free surface and two immiscible fluids. What turbulence model are you using (if you are using ine at all)?
Regards

kabilan February 10, 2011 05:28

vof
 
very thank you for reply,
i used k-e turbulence model............

Hermanus Henning February 10, 2011 08:43

Pleasure,
I used the Transition SST model for my case...

harish123 April 23, 2012 05:51

Quote:

Originally Posted by jack1980 (Post 264090)
Hi,

What you could do is:

- Have a split water velocity inlet and air velocity inlet. You can set the volume fraction of the water inlet to 1 in the boundary conditions panel

- For all other boundaries you will not have to make a distinction for the phase. This means you can have a single wall boundary and a single pressure outlet (with udf)

Have a look at pages 62 - 65 of https://docs.google.com/fileview?id=...MjNkZGJl&hl=en

Another option is open channel flow

Dear Jacks,
Thanks for your reply on CFD online regarding VOF.
I have certain doubts like you said you have single outlet how it is possible bcz then udf will give different pressure for air outlet as air is having different density.
Also should we include wall adhesion and surface tension also.
Air should be compressible or incompressible.

If you can mail me on my mail id - rrmore@gmail.com i will verymuch thankful to you......

mehulkumar November 30, 2012 01:43

Hi,

I am trying to simulate flow around the ship hull using 2D, steady state, VOF simulation.

I have given air and water velocity as 1m/s, but due to some reason within 10 iterations velocity is going to high !!!

Can any buddy help in identify the reason for such a high velocity?

Thanks in advance.

Mehul

like.no.other September 20, 2013 11:02

Hi guys
This is a good pdf for ship hull simulation
Heave and Pitch Simulation of Ship hull moving through head sea waves


enjoy!

Centurion2011 September 25, 2013 03:50

Quote:

Originally Posted by like.no.other (Post 452784)
Hi guys
This is a good pdf for ship hull simulation
Heave and Pitch Simulation of Ship hull moving through head sea waves


enjoy!

what is the password for .rar files from http://www.cfdiran.ir/download/ ?


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