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-   -   Complex multiphase melting problem (http://www.cfd-online.com/Forums/cfx/88628-complex-multiphase-melting-problem.html)

leff May 22, 2011 09:41

Complex multiphase melting problem
 
Hi,

The problem i'm dealing with involves the pouring of molten steel into enclosure which contains an aluminum block.
I would like to simulate the melt process of the aluminum block by the molten steel. In such case, it becomes a 3 liquids problem (molten steel, molten aluminum and air).
Is ANSYS CFX capable of performing such calculations?

I would appreciate your help a lot!!

Thanks

ghorrocks May 22, 2011 19:54

Yes, but you will have to do a lot of development in melting models. This sort of stuff is not built in. CFX support might have some examples of melting to get you started, but expect to do a lot of model development before it is accurate.

Redpoko May 23, 2011 04:20

Quote:

Originally Posted by ghorrocks (Post 308789)
Yes, but you will have to do a lot of development in melting models. This sort of stuff is not built in. CFX support might have some examples of melting to get you started, but expect to do a lot of model development before it is accurate.

hi ghorrocks, How good could CFX deal with another relative simple case -- pouring of molten steel into a pool and part of the steel are solidified on the bottom of the pool?

leff May 23, 2011 10:12

Hi Redpoko,

The case you presented seems to be much simpler than mine. Would you like to model the pouring process also or is it enough to start from a filled pool?
For the first case, it would be a 2-phase problem (mine is 3). Try google for commercial casting problems. Several codes such as FLOW3D, MAGMA, etc. are designed especially for casting problem.
In the second case, it would be a simple 1 phase problem, which I don't think is an issue.

leff May 23, 2011 10:21

Quote:

Originally Posted by ghorrocks (Post 308789)
Yes, but you will have to do a lot of development in melting models. This sort of stuff is not built in. CFX support might have some examples of melting to get you started, but expect to do a lot of model development before it is accurate.


ghorrocks! Thanks for the reply!
Could you please extend your reply on which models I would have to develop(in CFX programing language, right?) ?

As a first step I was thinking to model to the molten steel and air as liquids only. The Aluminum would be a solid, and I'm interested in obtaining the heating of it, without becoming liquid nor absorbing latent heat.
Would it still require development of melting models?

Thanks again! :)

ghorrocks May 23, 2011 18:57

Quote:

As a first step I was thinking to model to the molten steel and air as liquids only. The Aluminum would be a solid, and I'm interested in obtaining the heating of it, without becoming liquid nor absorbing latent heat.
That is a much simpler model as there is no phase change. This can be done with the models already in CFX I suspect.

The tricky bit will be the phase change of the aluminium melting. That will require development.

Redpoko May 24, 2011 15:27

Quote:

Originally Posted by leff (Post 308875)
Hi Redpoko,

The case you presented seems to be much simpler than mine. Would you like to model the pouring process also or is it enough to start from a filled pool?
For the first case, it would be a 2-phase problem (mine is 3). Try google for commercial casting problems. Several codes such as FLOW3D, MAGMA, etc. are designed especially for casting problem.
In the second case, it would be a simple 1 phase problem, which I don't think is an issue.

hi Leff, my case is to simulate the solidification process from a filled pool. sounds not that difficult, right? Actually I've even simplified the model to such a simplest 2D case that the top side is adiabatic BC, and the bottom side is solid-liquid interface, which needs to be set as isothermal BC (mushy zone ignored). Inside pool is the liquid material. SST k-w has been used here.

However, during the iteration the energy imbalance is always 100%. Finally simulation is terminated by fatal errors after 3000 steps. I am still working on it to figure out what's wrong with it. If you have any ideas, i am very glad to be informed. :)

ghorrocks May 24, 2011 19:27

Quote:

my case is to simulate the solidification process from a filled pool. sounds not that difficult, right?
Anything which involves phase change is complex and CFX does not have much built in for solidification. If there is no phase change then CFX should be able to handle it far better. If you are doing casting modelling I would consider casting software, such as the ones leff quoted, and there are many others (thermcast etc)

baserinia May 28, 2011 21:03

Quote:

Originally Posted by Redpoko (Post 309066)
hi Leff, my case is to simulate the solidification process from a filled pool. sounds not that difficult, right?

I have some experience with casting/solidification modeling in CFX. I agree with ghorrokcs; CFX has no built-in feature for solidification. However, you can model your problem with a little bit of work.

To model the evolution of latent heat, you have two options:
1- Define two different materials for the liquid and solid phases of aluminum. Make sure that the difference between the reference enthalpies of solid and liquid phases at the melting temperature is equal to latent heat of fusion.
2- Take the derivative of the enthalpy curve of your material to obtain the c_p curve, which must have a peak at the melting temperature. Use it as the specific heat of your material.

To model the solid phase, you have to add a dominant source term in momentum equation to overwrite the CFX calculated velocity field. You can also use a high value for the viscosity of the solid phase.

shahid nadeem March 17, 2014 04:04

AL and Si casting
 
My Dear Friends i want to simulate a problem where in have to casting for al and si liquids in a single jar with rotating. i want to find the volume of aluminium and silica after getting solidified. silica is 15% and al is 85%.
Please help me

ghorrocks March 17, 2014 04:44

Sounds like you need casting simulation software, not a general CFD code like CFX. CFX does not have models to do what you want to do.

shahid nadeem March 18, 2014 01:35

no dudue i feel we can do it in FLUENT but exactly how i dont know

ghorrocks March 18, 2014 17:46

You can do it in CFX as well but you are going to have the develop a lot of models to get it to work. If you are not experienced in CFD development then I recommend you use software specifically written to model casting, such as http://www.transvalor.com/en/cmspages/thercast.6.html or https://www.esi-group.com/software-s...turing/casting


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