CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

Erosion modelling

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 11, 2012, 20:21
Default Erosion modelling
  #1
Ugo
New Member
 
Ugonna
Join Date: Aug 2012
Posts: 7
Rep Power: 5
Ugo is on a distinguished road
Hi everyone, I really need help with my erosion model.. I am using the k-omega turbulence model, and if I dnt specify a discrete phase, it converges. But once I specify a discrete phase, it never converges, and continuosly says turbulent viscosity greater than 1e+5...

secondly, i have to verify that my results are correct. can anyone help me with coefficients commonly used in ersosion models and data to prove their validity...

Thanks

Ugo
Ugo is offline   Reply With Quote

Old   August 16, 2012, 05:15
Default
  #2
New Member
 
CFD-student's Avatar
 
Join Date: Dec 2011
Location: Sweden
Posts: 13
Rep Power: 5
CFD-student is on a distinguished road
Hi Ugo,

Regarding your first question, are you trying to simulate the particles in a 1-way or 2-way coupled fashion? Usually turbulent viscosity limitations stems from low quality meshes or ill defined turbulent boundary conditions.

Regarding your second question I would recomend you to use one of the main erosion models for example the model proposed by DNV, det norska veritas in their report DNV RP O501 which you can obtain for free. Their model is claimed to be experimentally validated for sand impingement in hydrocarbon mixtures.
CFD-student is offline   Reply With Quote

Old   August 16, 2012, 05:43
Default
  #3
Ugo
New Member
 
Ugonna
Join Date: Aug 2012
Posts: 7
Rep Power: 5
Ugo is on a distinguished road
Hi CFD-Student,
Thanks for replying. its actually a 1-way coupled erosion by fly ash in preheater tubes. I cant seem to find a way to relate the values i get in FLUENT, to an empirical formulae. I model with impatc angles and coefficients, and discovered that maximum erosion occurs at tthe 35 degree angle. but then how do I validate it with the empirical formulae.

Thanks once again.
Ugo is offline   Reply With Quote

Old   August 16, 2012, 05:55
Default
  #4
New Member
 
CFD-student's Avatar
 
Join Date: Dec 2011
Location: Sweden
Posts: 13
Rep Power: 5
CFD-student is on a distinguished road
Np at all,
If you are employing a 1-way coupled simulation. Then you first solve the flow field without specifying the discrete phase. Thereafter you implement the discrete phase but you dont start any iterations via the solver. You just go the report > sample and then sample the erosion. Particle trajectories are calculated on the already resolved flow field without updating the solution.

While the erosion process is highly complicated, empirical formulae often just predict the maximum erosion rate in for example en elbow but dont give any information about the location of maximum erosion. The advantage with CFD is that you can get this kind of localized information. The maximum erosion rate you obtain should be bounded by the values you get from empirical formulae. Keep in mind that erosion modeling is highly complicated and often results only with an accuracy of one order of magnitude can be obtained. Due to this correlations are often highly conservative.
CFD-student is offline   Reply With Quote

Old   August 16, 2012, 06:11
Default
  #5
Ugo
New Member
 
Ugonna
Join Date: Aug 2012
Posts: 7
Rep Power: 5
Ugo is on a distinguished road
Hi
When i specified it, it just gave me "number tracked = 690, escaped = 690, aborted = 0, trapped = 0, evaporated = 0, incomplete = 0" and nothing more, I didnt get a particle trajectory data impact angle data.
Do I have to specify things like wall boundary conditions, I used coefficients from Tabakoff from a tutorial I saw online, and an injection velocity of 4m/s. I dnt really know if I am doing the right thing....If it would not be too much hassle for your, could you give me a step-by-step approach to how this is done. There are quite a number of values I have to specify, and I do not know if in the 1-coupled mode, they are required, e.g particle diameter, total flow rate etc... Thanks, I am really grateful
Ugo is offline   Reply With Quote

Old   August 16, 2012, 06:20
Default
  #6
Ugo
New Member
 
Ugonna
Join Date: Aug 2012
Posts: 7
Rep Power: 5
Ugo is on a distinguished road
Hi CFD-Student, I forgot to add my email address, ugocpu@yahoo.com. Please if you have anything that could help me out, especially in the process of 1-way coupled simulation, please do send it... How do I actually obtain the impact angles of the ash particles?

Thanks kindest regards
Ugo is offline   Reply With Quote

Reply

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
FLUENT erosion modelling ckwollongong FLUENT 2 August 13, 2013 02:12
Erosion modelling Ugo FLUENT 0 August 5, 2012 19:30
Modelling Sand erosion using Mixture model and DPM karlchapman FLUENT 3 July 5, 2012 08:55
error message cuteapathy CFX 14 March 20, 2012 07:45
Erosion problem Ko CD-adapco 2 September 24, 2003 07:48


All times are GMT -4. The time now is 06:30.