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

Herschel-Bulkley model

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 1, 2001, 03:47
Default Herschel-Bulkley model
  #1
merac
Guest
 
Posts: n/a
Hello everyone, does anybody know a way of incorporating the Herschel-Bulkley (yield Power-Law) rheological model into Fluent? Fluent currently deals with Power-Law non-Newtonian fluids, so can it be modified (maybe by a UDF) to simulate Herschel-Bulkley? If so, how would you go about this? Thanks for any answers in advance!
  Reply With Quote

Old   May 2, 2001, 03:10
Default Re: Herschel-Bulkley model
  #2
Anthony Wachs
Guest
 
Posts: n/a
Hi,

I have implemented yield stress fluids in Fluent : both Bingham and Herschel-Buckley models. It works pretty good. I have programmed an UDF that takes into account the yield stress. In fact, you have to define an UDF for the viscosity using a regularization model to avoid the discontinuity of the model around the yield stress. In my work, I consider the Papanastasiou exponential model for the regularization, but the bi-viscosity model can also be used. Comparisons with analytical solutions in Poiseuille flow in axisymmetric pipes show satisfactory agreement.

Do not hesitate to contact me if you'd like to have some additional informations.

Hope it can help you!!

Anthony
  Reply With Quote

Old   June 7, 2011, 22:02
Default Herschel-Bulkley
  #3
New Member
 
CFD-World
Join Date: May 2011
Posts: 1
Rep Power: 0
mehdi27 is on a distinguished road
Hi Anthony,

I am stuck by modeling Herschel-Bulkley model for a long time. Would you please give me more hints?

I have read your posts and concluded this model based on them;

Apparent viscosity= PV+((1-exp(-m*sr))*yp)/sr
PV: plastic viscosity
yp: yield point
sr: shear rate, in fact the bingham plastic model: shear stress=yp+pv*sr

when I choose m=100, the model works until the end that crashes. However still I get some results which is 2 times the exact solution.
i supposed, if I select very big number for m, for instance 10^6, then I should get better results, but I got very strange numbers.

Would you please help me?

Regards




Quote:
Originally Posted by Anthony Wachs
;96933
Hi,

I have implemented yield stress fluids in Fluent : both Bingham and Herschel-Buckley models. It works pretty good. I have programmed an UDF that takes into account the yield stress. In fact, you have to define an UDF for the viscosity using a regularization model to avoid the discontinuity of the model around the yield stress. In my work, I consider the Papanastasiou exponential model for the regularization, but the bi-viscosity model can also be used. Comparisons with analytical solutions in Poiseuille flow in axisymmetric pipes show satisfactory agreement.

Do not hesitate to contact me if you'd like to have some additional informations.

Hope it can help you!!

Anthony
mehdi27 is offline   Reply With Quote

Old   February 4, 2014, 02:33
Default
  #4
Member
 
Satish Gupta
Join Date: Jun 2012
Posts: 30
Rep Power: 5
Rahul123 is on a distinguished road
Hi anthony,
I am also trying to use hershel-bulkley model with papanastasiou approximation. Will only changing the viscosity with a udf do the trick. how will I enter the parameters like n (power index). Where should I attach the udf.
Rahul123 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
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
Herschel Bulkley model Problem emad FLUENT 5 May 18, 2012 13:25
Reynolds Stress model in CFX vs Fluent Tim CFX 1 October 7, 2009 06:19
Regarding Implementation of Hershel Bulkley Model in Viscosity correlation Pathak FLOW-3D 0 August 24, 2009 06:34
multi fluid mixture model issue rystokes CFX 3 August 9, 2009 19:13


All times are GMT -4. The time now is 02:13.