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

A question about the access of properties?

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 27, 2010, 01:45
Default A question about the access of properties?
  #1
New Member
 
zouzheng
Join Date: Jun 2010
Posts: 5
Rep Power: 7
zouzhengkaoyan is on a distinguished road
Hello! In the UDF of Fluent, is there any difference among the macro of MATERIAL_PROP( , ),generic property (name,c,t,prop,id,T)and C_***(c,t),such as MATERIAL_PROP(sp,PROP_RHO),generic property (name,c,t,PROP_RHO,id,T) and rho_s= C_R(cell, htread_s)?
Thank you in advanced!
zouzhengkaoyan is offline   Reply With Quote

Old   July 2, 2010, 17:28
Default
  #2
TDi
Member
 
Tim Diller
Join Date: Mar 2010
Location: Austin, TX
Posts: 32
Rep Power: 7
TDi is on a distinguished road
I think those must be the same thing. They're all macros defined by Fluent.
TDi is offline   Reply With Quote

Old   July 4, 2010, 23:11
Default
  #3
New Member
 
zouzheng
Join Date: Jun 2010
Posts: 5
Rep Power: 7
zouzhengkaoyan is on a distinguished road
Thank you ! May be they are the same, but I find the results are not same using different macro!
zouzhengkaoyan is offline   Reply With Quote

Old   October 31, 2014, 02:56
Default
  #4
New Member
 
Georgy
Join Date: Apr 2011
Location: Russia
Posts: 19
Rep Power: 6
gera is on a distinguished road
Hello!

As far as I can judge, the difference is following.

MATERIAL_PROP(sp,PROP_mu) returns the value of viscosity if it is constant. If we use power dependence on temperture the returned value is zero.

generic_property(c,t,PROP_mu,i,T) takes into account temperature in cell c; so we can use viscosity as a function of temperature, but I found that it does not work for power-law option. At the same time, it works well for polynomial option.

Does anybody know how to get viscosity of mixture component if viscosity has the power-law option?

Thank you!
gera is offline   Reply With Quote

Old   October 31, 2014, 08:40
Default
  #5
Senior Member
 
ghost82's Avatar
 
Daniele
Join Date: Oct 2010
Location: Italy
Posts: 910
Rep Power: 15
ghost82 will become famous soon enough
If you can't access the mixture viscosity when it is set to power-law, what do you think of write the udf for mixture power-law viscosity, declare as a global variable the mixture viscosity so you can access it in other macros?
ghost82 is online now   Reply With Quote

Old   October 31, 2014, 08:49
Default
  #6
New Member
 
Georgy
Join Date: Apr 2011
Location: Russia
Posts: 19
Rep Power: 6
gera is on a distinguished road
I've done it. Of course, it works fine, but if I change viscosity in GUI of Fluent, I need to change my udf. This is inconvinient. So the idea was to use fluent for viscosity calculation. In that case if user changes the viscosity law, for example, to "kinetic" then udf-code automatically uses new viscosity dependence (not necessary to re-compile).
gera 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
Question of properties in two phase solver mmjhuang OpenFOAM Running, Solving & CFD 2 October 29, 2012 23:56
General question what fluid properties do you use harly OpenFOAM Running, Solving & CFD 0 November 18, 2008 16:38
Poisson Solver question Suresh Main CFD Forum 3 August 12, 2005 04:37
Addiotional scalar properties: gas or liquid? Julie Polyakh CD-adapco 0 June 20, 2004 15:54
question K.L.Huang CD-adapco 1 March 29, 2000 04:57


All times are GMT -4. The time now is 11:39.