Ramp BC per Iteration

AndyR · August 25, 2010, 11:21

I have a converged Steady State solution. I am running a family of solutions with slightly different boundary conditions. In this case I am varying the swirl at an inlet. For low values of swirl I find that I can use the existing solution simply change the values and keep running. As the absolute value gets large, I find that the amount of change the solution can absorb without diverging gets small. Even with signifcant relaxation and a small CFL number.

I think it would be simplest to define a UDF which ramps the swirl from one value to the next over some number of iterations. I understand how to define the profile, but not how to access the iteration number in an UDF.

Any help is appreciated
Thanks
- Andy R

coglione · August 26, 2010, 03:04

N_ITER is the macro you are looking for. It retutns the number of iterations performed since you initialized your solution. As far as i know it works only in compiled udfs.

cheers

wpdeng · March 6, 2018, 01:36

Hi,

I simplified 3D geometry to 2D axisymmetry swirl. And I want to load a heat source about space distribution, but it's wrong when I use Cartesian coordinate system.

What should I do to deal with it?

August 25, 2010, 11:21	Ramp BC per Iteration	#1
AndyR Member Andy Robertson Join Date: Mar 2009 Location: Long Island NY Posts: 46 Rep Power: 17	I have a converged Steady State solution. I am running a family of solutions with slightly different boundary conditions. In this case I am varying the swirl at an inlet. For low values of swirl I find that I can use the existing solution simply change the values and keep running. As the absolute value gets large, I find that the amount of change the solution can absorb without diverging gets small. Even with signifcant relaxation and a small CFL number. I think it would be simplest to define a UDF which ramps the swirl from one value to the next over some number of iterations. I understand how to define the profile, but not how to access the iteration number in an UDF. Any help is appreciated Thanks - Andy R

August 26, 2010, 03:04		#2
coglione Senior Member Max Join Date: Mar 2009 Posts: 133 Rep Power: 17	N_ITER is the macro you are looking for. It retutns the number of iterations performed since you initialized your solution. As far as i know it works only in compiled udfs. cheers sam_paris and Ionut G like this.

March 6, 2018, 01:36	Axisymmetric swirl-----space distribution for UDF	#3
wpdeng New Member DENG Weriping Join Date: Jun 2015 Posts: 16 Rep Power: 10	Hi, I simplified 3D geometry to 2D axisymmetry swirl. And I want to load a heat source about space distribution, but it's wrong when I use Cartesian coordinate system. What should I do to deal with it?

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
how to increase "Newton Pressure Iteration Limit"	kus	CFX	9	April 21, 2013 01:54
non stoppage of iteration	alastormoody11	CFX	0	July 15, 2010 04:33
Parallel runs slower with MTU=9000 than MTU=1500	Javier Larrondo	FLUENT	0	October 28, 2007 22:30
Creating, loop or iteration using expression edito	Jan	CFX	3	July 28, 2003 11:01
Heat exchanger problem	chiseung	FLUENT	16	October 20, 2001 04:36