Ramp BC per Iteration

AndyR · August 25, 2010, 12:21

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, 04:04

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, 02:36

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, 12:21	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, 04:04		#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, 02:36	Axisymmetric swirl-----space distribution for UDF	#3
wpdeng New Member DENG Weriping Join Date: Jun 2015 Posts: 16 Rep Power: 11	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?

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