|
[Sponsors] |
September 16, 2010, 03:24 |
turbulence model
|
#1 |
New Member
Ali Jafarizade
Join Date: May 2009
Posts: 22
Rep Power: 16 |
hi
are the turbulence models that used for newtoninan fluid diffrent from non-newtonian fluid in fluent? how about in general? thanks in advance |
|
September 21, 2010, 16:57 |
|
#2 |
Senior Member
Join Date: Feb 2010
Posts: 148
Rep Power: 17 |
I asked ANSYS tech support, whose response is below.
The turbulence models for use with non-Newtonian fluids are the same as those for newtonian fluids. Newtonian fluids are implemented by changing the viscosity dependency for the fluid material; the other selections stay the same. I do not quite understand so I'm asking for clarification. However, I thought I'd go ahead and respond with the information thus far. Last edited by Jade M; September 23, 2010 at 12:55. |
|
September 22, 2010, 04:07 |
|
#3 |
Senior Member
Hamid Zoka
Join Date: Nov 2009
Posts: 282
Rep Power: 18 |
I am not sure about it.
what about bossinesque approxiamtion? how is turbulence viscosity in non-newtonian fluids defined? turbulence characteristics of newtonian fluids seems to be different than newtonains. |
|
September 23, 2010, 12:40 |
|
#4 |
Senior Member
Join Date: Feb 2010
Posts: 148
Rep Power: 17 |
I am not quite satisfied with the response either. When I asked for elaboration, tech support responded
I meant that all the turbulence models we have support non-newtonian fluids. The implementation of non-newtonian viscosity is similar to making property change to the fluid. The Non-Newtonian model just allows viscosity to depend on Shear stress and other variables. I also submitted a new service request to see the response from another person, who stated With non-Newtonian models we generally alter only the dynamic viscosity term, other terms are calculated in the same fashion. I still do not completely understand but this is all the time that I have to devote to this issue at the moment. From the CFX documentation, it looks like built-in non-Newtonian dynamic viscosity models are new in Release 12, which is probably a great improvement. However, I do not see anything in reference to turbulence modelling. I spent a great deal of time understanding turbulence modelling earlier this year and did not see anything in reference to non-Newtonian fluids in the CFX documentation. I am not sure as to a good source to refer you to. If you have access to ANSYS tech support, I would suggest directing questions to them. Good luck! |
|
September 25, 2010, 01:34 |
|
#5 |
Senior Member
N/A
Join Date: Mar 2009
Posts: 189
Rep Power: 17 |
I agree with Hamid. The Boussineq approximation does not hold for non-newtonian fluids and the definition of turbulent viscosity has to be modified. There was a study on the addition of polymer particles in blood a while ago (2002 maybe) and they found that the flow became turbulent at Re ~ 100.
You can trying using the Reynolds stress models (provided the numerical computations remain stable). Another option might be to check the documentation of OpenFOAM online. The implementation of a non newtonian turbulence model might be similar in Fluent and OpenFOAM. Good luck, Harish |
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Superlinear speedup in OpenFOAM 13 | msrinath80 | OpenFOAM Running, Solving & CFD | 18 | March 3, 2015 05:36 |
Low Reynolds k-epsilon model | YJZ | ANSYS | 1 | August 20, 2010 13:57 |
KOmega Turbulence model from wwwopenFOAMWikinet | philippose | OpenFOAM Running, Solving & CFD | 30 | August 4, 2010 10:26 |
Fan heater model: what turbulence source to use? | andy20 | CFX | 7 | March 3, 2008 16:42 |
SSG Reynolds Turbulence Model | Georges | CFX | 1 | February 28, 2007 16:15 |