CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT > Fluent Multiphase

Very low steam fraction RPI boiling

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 26, 2023, 11:23
Default Very low steam fraction RPI boiling
  #1
Member
 
Pierre LECHEVALIER
Join Date: Mar 2023
Posts: 31
Rep Power: 3
PierreLCV is on a distinguished road
Dear All,

I am currently working on my first CFD boiling simulation using RPI model and I face an issue I can not fix. I have started with a very straightforward steady state situation, vertical tube 20mm diameter and 2000mm length. Water inlet at the bottom at 20°C, 1 bar and 1m/s.
I have imposed a heat flux on the wall which i increase gradually simulation after simulation. It appears that the monophasic situation works very well. I activate the multiphase model when the temperature on the wall is about to reach the saturation temperature and that's where the problem start. Indeed, whatever the heat flux imposed, the steam volume fraction remains very low (i can not reach more than e-5). I have tried to increase a lot the heat flux but the solver diverge then...
Briefly, my simulation is working very well in monophasic state (even when the multiphase option is activated when the heat flux is low enough) but when the heat flux is high enough to create steam, the fraction remains very low whatever the flux.
As it is my first RPI boiling simulation, i am using the "default" values for all the RPI model parameters adviced by Fluent Manual.
I precise that I have activated the gravity...


Any idea ?
Thank you for your help !


Pierre
PierreLCV is offline   Reply With Quote

Old   November 13, 2024, 13:22
Default
  #2
New Member
 
gulab verma
Join Date: Feb 2023
Posts: 2
Rep Power: 0
gulab1708 is on a distinguished road
i also want answer for the same. have you got the solution?
gulab1708 is offline   Reply With Quote

Old   November 13, 2024, 15:29
Default
  #3
Member
 
Pierre LECHEVALIER
Join Date: Mar 2023
Posts: 31
Rep Power: 3
PierreLCV is on a distinguished road
Dear gulab1708,
This post is quite old now, but I am still working on this subject, so maybe I can help . I do not know exactly what is your issue but if the situation is close to mine in May 2023 I suggest you to start from the Bartolomei validation case (you will find it on the Ansys Help site).
If you have specific question please do not hesitate to ask I will try to help you on this difficult but passionating subject !

You can also send me directly a message/email


Best regards,
Pierre
PierreLCV is offline   Reply With Quote

Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Convergence Issue Of RMS Mass Vapour in RPI Boiling Model in CFX nomi.tahir Main CFD Forum 1 May 28, 2018 04:56
Free surface issues with interDyMFoam for hydroturbine oumnion OpenFOAM Running, Solving & CFD 0 October 6, 2017 15:05
multiphaseEulerFoam (OF2.3.0) : Courant number explodes when running in parallel Mehrez OpenFOAM Running, Solving & CFD 10 May 18, 2016 12:44
CFX Solver Memory Error mike CFX 1 March 19, 2008 08:22
Multicomponent fluid Andrea CFX 2 October 11, 2004 06:12


All times are GMT -4. The time now is 15:33.