[Mfaizan]

Hi All,

I am developing a 3D multicomponent model in CFX. I am trying to couple two fluids nitrogen and air. I have defined the domains. The problem statement is such nitrogen is in a Nozzle and entering into the surrounding air domain. the surrounding air domain is a large room. Now my confusion is that how can I be sure that nozzle inside volume contains nitrogen fluid material and surrounding air domain contain air fluid material. Because when I see the material tab which shows both fluid in alphabetical order.

How can I check that I have inserted the right fluid material to right domain?????? anyone can help will be appreciated alot....

[fresty]

Originally Posted by Mfaizan

Hi All,

I am developing a 3D multicomponent model in CFX. I am trying to couple two fluids nitrogen and air. I have defined the domains. The problem statement is such nitrogen is in a Nozzle and entering into the surrounding air domain. the surrounding air domain is a large room. Now my confusion is that how can I be sure that nozzle inside volume contains nitrogen fluid material and surrounding air domain contain air fluid material. Because when I see the material tab which shows both fluid in alphabetical order.

How can I check that I have inserted the right fluid material to right domain?????? anyone can help will be appreciated alot....

HI,

Trying to comprehend your question, domain material selection is only executed after selecting a particular meshed region which i presume you must have, so i do not see how you would be unsure of the selection.
Can you please, post some rough sketch or some sort of reference to look at, to understand the issue here.

Thanks.

P.S. http://www.cfd-online.com/Forums/cfx...ease-read.html

[Mfaizan]

Attachment 36102

HPGas Nitrogen.jpg

Hi fresty,

Thanks for response- I have attached pics of Air domain and HPgas which is nozzle inside domain having nitrogen. Now if you can see at material tab, there is no change of assigned material when changing domains. Both air and hpgas domain showing N2 material as first material.

I have this confusion as if have correctly assigned the correct material to correct mesh regions....Please suggest..

Thanks

[Opaque]

Not exactly sure what you are trying to model; however, if you are trying to model a mixture of gases you are approaching it the wrong way. It seems you are setting up the problem as a CFX multiphase simulation.

Have you reviewed the tutorials for mixing "CFX materials" (not "CFX phases")? If you follow those tutorials you may save considerable time and frustrations.

[Mfaizan]

Hi Opaque,

You are absolutely RIGHT. I am trying to mix two fluids one is nitrogen inside the nozzle with inlet conditions as 14 bar total pressure and 550C total temperature. The other fluid is surrounding air which is at ambient temperature and pressure. It is a mixture CFX model and it is not a multiphase model.

I have been reading cfx documentation but I am unable to setup the case. I also searched tutorial but its all referring to multiphase. I need a multicomponent tutorial. Please suggest me a link or any reference where I can get some help.

Many many thanks in advance.

[Opaque]

You can refer to the following tutorials:

"Reacting Flow in a Mixing Tube"

"Combustion and Radiation in a Can Combustor"

"Steam Jet" (this is a multicomponent-multiphase tutorial"

You must create the mixture material before you attempt to associate domains to meshes, and material to phases.

[Mfaizan]

Thanks Opaque indeed.

Actually I have one confusion that if I defined the material as mixture initially then how can I get the physics of two fluids?

As I mentioned that nitrogen is at 14bar pressure and 550C while air is a surrounding/room fluid with ambient condition like 1 atm pressure and 25C temp?

please suggest...

Many thanks

[fresty]

Agree with Opaque on the comments of using mixture of fluids as the right approach. Multiphase per my humble understanding deals with a domain with existing multiple fluids (vapors, mist etc.).
If you go through the tutorials suggested by Opaque you would get most of the answers to your questions/ confusion.
Domain initial conditions in a fluid mixing model can be different and do not affect until the flow domains from both mesh regions interact/ are interfaced, which i presume you will define (inlet and outlet of nozzle).

Thanks.

[ghorrocks]

The CFX documentation has a much better definition of the difference between multicomponent and multiphase:

Multiphase flow refers to the situation where more than one fluid is present. Each fluid may possess its own flow field, or all fluids may share a common flow field. Unlike multicomponent flow, the fluids are not mixed on a microscopic scale in multiphase flow. Rather, they are mixed on a macroscopic scale, with a discernible interface between the fluids. ANSYS CFX includes a variety of multiphase models to allow the simulation of multiple fluid streams, bubbles, droplets, solid particles, and free surface flows.

[Elechi]

I have a homogeneous binary mixture of saltwater material and water vapor, Is it possible for me to use this homogeneous binary mixture as a liquid component in a multiphase flow?

What I find hard to understand is if the homogeneous binary mixture material is also a multicomponent material. If it can be used, how do I setup a multicomponent multiphase flow model in Ansys cfx? Thank you.