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

Urgent help needed in creating UDF's

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 11, 2013, 23:48
Post Urgent help needed in creating UDF's
  #1
New Member
 
Sharath Chandra. J
Join Date: Sep 2013
Posts: 2
Rep Power: 0
sharath chandra is on a distinguished road
I am currently working on validation of a small project and it includes flow conditions in parabolic profile and temperature conditions varying in a linear fashion increasing along the Y axis.

Velocity varies as
u(y)=12(y-(y^2)) and y ranges from -1/6 to 1/2

Temperature varies as
θ(y)=(1-2y) and again y ranges from-1/6 to 1/2

My main problem is i don't understand how to define the centre-line velocity i.e maximum velocity and temperature conditions. Also from a previous experience, I couldn't include two different UDF's for different boudary conditions. Is it possible to write both the UDF's in a single program

I have included all the required data probably. In case anything else is required, I would respond. Please help me out.
Attached Images
File Type: jpg help required.jpg (58.2 KB, 12 views)
sharath chandra is offline   Reply With Quote

Old   October 12, 2013, 09:55
Default
  #2
Senior Member
 
ghost82's Avatar
 
Daniele
Join Date: Oct 2010
Location: Italy
Posts: 490
Rep Power: 11
ghost82 will become famous soon enough
Quote:
Originally Posted by sharath chandra View Post
I am currently working on validation of a small project and it includes flow conditions in parabolic profile and temperature conditions varying in a linear fashion increasing along the Y axis.

Velocity varies as
u(y)=12(y-(y^2)) and y ranges from -1/6 to 1/2

Temperature varies as
θ(y)=(1-2y) and again y ranges from-1/6 to 1/2

My main problem is i don't understand how to define the centre-line velocity i.e maximum velocity and temperature conditions. Also from a previous experience, I couldn't include two different UDF's for different boudary conditions. Is it possible to write both the UDF's in a single program

I have included all the required data probably. In case anything else is required, I would respond. Please help me out.
Hi!
Please define your equations; if I plot the velocity equation between -1/6 and 1/2 I have negative velocities and the profile of the parabola is not complete.
If I translate the parabola and if I plot that translated parabola the profile of the parabola is not complete.

Do the same with the T equation.

Can you define better your problem?

Daniele
Attached Images
File Type: jpg chart.jpg (27.3 KB, 7 views)
ghost82 is offline   Reply With Quote

Old   October 12, 2013, 13:12
Post RE: Data clarification
  #3
New Member
 
Sharath Chandra. J
Join Date: Sep 2013
Posts: 2
Rep Power: 0
sharath chandra is on a distinguished road
Quote:
Originally Posted by ghost82 View Post
Hi!
Please define your equations; if I plot the velocity equation between -1/6 and 1/2 I have negative velocities and the profile of the parabola is not complete.
If I translate the parabola and if I plot that translated parabola the profile of the parabola is not complete.

Do the same with the T equation.

Can you define better your problem?

Daniele
Hi! First let me thank you for such an immediate response. I am really grateful to you for your help. Anyways back to the problem at hand.

The problem I am working on is a backward facing step flow with varying expansion ratios. I have to validate the flow conditions in the problem for varying ratios of S/H as shown form the figure. From the paper I've been trying to validate this sentence is verbatim.
" The physical domain in the X-direction is bounded by 0 < x < (30H) and in the y direction it is bounded by S/DH < y < 1/2.
The flow at the inlet, x=0 is assumed to be hydro-dynamically fully developed, where a dimensionless parabolic velocity distribution is given as
u(y)=12(y-y^2)."
If having the Reynolds number of the flow would be helpful, then it is 800 and the fluid is assumed as water with standard properties.
sharath chandra is offline   Reply With Quote

Reply

Tags
temperature bc, udf, velocity bc

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
urgent help needed (rhie-chow interpolation problem) Ardalan Main CFD Forum 2 March 18, 2011 16:22
Parse error in UDF, URGENT HELP NEEDED!!! Boris Kloser FLUENT 2 December 12, 2009 03:16
help needed in Turbulent flow (URGENT) mike FLUENT 7 November 7, 2008 06:11
Urgent help needed with spray injection nick CD-adapco 14 June 29, 2008 18:48
Urgent Help Needed! Ken Adams FLUENT 3 September 25, 2007 23:50


All times are GMT -4. The time now is 05:59.