[alibul]

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]

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]

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

[Hermanus Henning]

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]

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]

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]

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

[Hermanus Henning]

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

[harish123]

Originally Posted by jack1980

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]

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]

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]

Originally Posted by like.no.other

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/ ?

[agakristo]

Hi all,

if you are still interested in a simulation for a boat hull, then we started working on a collaborative project for a multiphase flow around a boat hull. We already have a group of people involved in it and the project is fully open to anyone additional who wants to join. We are posting all the results, images on the forum here:
https://forum.simscale.com/t/collabo...oat-hull/71/30

Would be great to have you join!

Cheers,

Agata

[ANKURIITD]

Hey guys,
I have simulated the steady state free surface flow around a wigley hull using FLUENT.I am having problem in calculating the wave making drag and other post processing. Can anyone help me in the post processing the results???

I am getting the Cd value=5.84e-3
My wave profile is close to the experimental results....
Please help me in finding the other resistance parameters...
Thank you

[M. GOWTHAM]

Hi Sir, my project is similar to yours I need some details about meshing, analysis , flow stimulation
If anybody have idea regarding Pls send the details to gowthamaero1117@gmail.com mail id

[sriram9127]

It is a multiphase problem(air and water).
Initial velocity zero for both phase.
I want to run a simulation for 1m/s velocity of both phases and view wave pattern.

Please find the attachment. The residuals are converged, but I can't find the entire wave pattern. Give me some suggestions.