CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Fluent UDF and Scheme Programming

Free water jet impinging hot solid surface, including boiling

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   January 25, 2011, 12:17
Default Free water jet impinging hot solid surface, including boiling
  #1
New Member
 
Hamdy
Join Date: Jan 2011
Posts: 9
Rep Power: 6
hamdy is on a distinguished road
I am working on round water jet that impinges hot surface at 400 deg C. The problem including boiling and wetting front propagation for water. I have the following problems:
  1. The number of phases are 3: air, water and water vapor, or 2: water and water vapor only.
  2. what is the recommended UDF in C format.
  3. How to activate vof model properly in this case
  4. Is there a need to set function hooks
  5. the case is interpreted or compiled
  6. is there any tutorial that may help
Awaiting for your kind help and support. Thanks...
hamdy is offline   Reply With Quote

Old   July 3, 2012, 07:53
Default
  #2
Member
 
subha_meter's Avatar
 
Subhasish Mitra
Join Date: Oct 2009
Location: Australia
Posts: 54
Rep Power: 7
subha_meter is on a distinguished road
If it's still important to you,

- The problem can be treated in both eulerian (air, water) and lagrangian (air, water droplet and water vapor) approach.
- The boiling model available in ansys 13/14 can be used for solid liquid heat transfer. UDF can also be used to model mass transfer phenomena.
- Species transport model will be required to account for vapor phase.
-turbulence model will also need to be incorporated.

Hope it helps,
__________________
SM
subha_meter is offline   Reply With Quote

Old   August 19, 2012, 05:28
Smile
  #3
New Member
 
Jan
Join Date: Feb 2012
Location: UK
Posts: 24
Rep Power: 5
canev.civelek is on a distinguished road
Hi Subha,

Im hoping you may be able to help with a similar problem.

I need to simulate a water jet into air, i have a simple rectangular domain.

I will be using vof. To set up this problem i have specified velocity inlet of 10ms with volume fraction of water as 1.

I was hoping this would allow the water to be injected into the domain however this is not correct.

Im a little confused how to approch this problem, will i need to create injection of upload a udf to specify the travel of the water.

I thought species transport may work but im still having problems with this.

I hope you can help, Thanks
canev.civelek is offline   Reply With Quote

Old   August 19, 2012, 08:24
Default
  #4
Member
 
subha_meter's Avatar
 
Subhasish Mitra
Join Date: Oct 2009
Location: Australia
Posts: 54
Rep Power: 7
subha_meter is on a distinguished road
Hi Caney,

Are you using a 3D grid? You can use a "velocity inlet" (a small orifice), "wall with slip" around and a "pressure outlet" as outlet boundary condition. A turbulence model will be required. You can use both eulerian-eulerian method and VOF to simulate the phenomena. If you are interested in jet length and shape, any of these approach will do. In either of these two case, you need to supply the velocity magnitude and water volume fraction = 1.0 at the inlet.

You can use DPM spray model to simulate the jet as well if you are interested to know the each droplet's fate. I don't envisage any species transport here if it's a cold jet being sprayed into air.

Regards,





Quote:
Originally Posted by canev.civelek View Post
Hi Subha,

Im hoping you may be able to help with a similar problem.

I need to simulate a water jet into air, i have a simple rectangular domain.

I will be using vof. To set up this problem i have specified velocity inlet of 10ms with volume fraction of water as 1.

I was hoping this would allow the water to be injected into the domain however this is not correct.

Im a little confused how to approch this problem, will i need to create injection of upload a udf to specify the travel of the water.

I thought species transport may work but im still having problems with this.

I hope you can help, Thanks
__________________
SM
subha_meter is offline   Reply With Quote

Old   August 19, 2012, 08:46
Default
  #5
New Member
 
Jan
Join Date: Feb 2012
Location: UK
Posts: 24
Rep Power: 5
canev.civelek is on a distinguished road
Hi Subha,

Thanks for the quick response. I am actually trying a 2D to start with.

I have an inlet with velocity magnitude of 10m/s and have specified the volume fraction of water as 1. I also have wall with no slip and pressure outlets.
I have set phase 1 as air and phase 2 as liquid. Is this correct?

When i run the simulation and check the volume fraction of the phases air and water, the air seems to appear at the pressure outlets. and water seems to be in the whole domain. This is confusing me.

I guess i have to simulate the water through the velocity inlet which for some reason i am not getting correct.

So you have an idea how i can solve this?

Thanks again for your help.
Regards

Sorry forgot to mention i am using vof model with species transport and LES turbulence model.

Last edited by canev.civelek; August 19, 2012 at 09:03.
canev.civelek is offline   Reply With Quote

Old   August 19, 2012, 19:52
Default
  #6
Member
 
subha_meter's Avatar
 
Subhasish Mitra
Join Date: Oct 2009
Location: Australia
Posts: 54
Rep Power: 7
subha_meter is on a distinguished road
Hi Caney,

I guess you are assigning the entire inlet boundary as "velocity inlet". This would fill the entire domain with water. Only the orifice at the inlet (few mm) needs to be assigned as velocity inlet and you should get a conical shape jet structure. Rest of the inlet boundary can be assigned as "wall with slip". Assign air as continuous phase and water as dispersed phase. No species transport is required. LES model is fine but you need to use a really dense mesh if you wish to resolve the eddies. Hope it helps.


Quote:
Originally Posted by canev.civelek View Post
Hi Subha,

Thanks for the quick response. I am actually trying a 2D to start with.

I have an inlet with velocity magnitude of 10m/s and have specified the volume fraction of water as 1. I also have wall with no slip and pressure outlets.
I have set phase 1 as air and phase 2 as liquid. Is this correct?

When i run the simulation and check the volume fraction of the phases air and water, the air seems to appear at the pressure outlets. and water seems to be in the whole domain. This is confusing me.

I guess i have to simulate the water through the velocity inlet which for some reason i am not getting correct.

So you have an idea how i can solve this?

Thanks again for your help.
Regards

Sorry forgot to mention i am using vof model with species transport and LES turbulence model.
__________________
SM
subha_meter is offline   Reply With Quote

Reply

Tags
boiling modeling, free water jet, quenching

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Free surface flow settubg boundary conditions and plotting velocity profiles prashanthreddyh FLUENT 1 December 2, 2009 12:06
Boiling of water with hot air Dr. Flow Squad CFX 2 July 27, 2009 07:37
solid edge problem....can you help? cindy Main CFD Forum 3 April 5, 2004 13:43
gravitational force for free surface flow Jongtae Kim Main CFD Forum 1 July 2, 2000 11:57
Radial jet with free surface using FIDAP Dr. Ahmed Hassaneen Main CFD Forum 0 October 28, 1999 13:20


All times are GMT -4. The time now is 13:33.