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April 16, 2014, 20:04 
[Tutorial 3] Doubts about iteration number

#1 
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Carlos Alexandre Tomigawa Aguni
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Did anyone do the Tutorial 3 (Laminar Cylinder)?
Why is it set to do 9999 iterations? If it's possible to change that what's the best suitable number to put? Thanks in advance! Edit1: This thread has advanced! Please check my following posts! Last edited by CrashLaker; April 16, 2014 at 22:09. 

April 16, 2014, 20:24 

#2 
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Carlos Alexandre Tomigawa Aguni
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I've noticed that 9999 was the maximum number of iterations..
So where do I find how many iterations is it set to do? My program goes far till 7k then crashes... Any help? 

April 16, 2014, 22:19 

#3  
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Carlos Alexandre Tomigawa Aguni
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I've just realized that running it in serial the calculations don't reach the breaking point (this I suppose is the convergence they talk about on the tutorial).
So.. when running it in serial or setting np = 1 (if one use any mpi implementation) it just goes till the 9999th iteration Can you explain why is that? Example where I've set np = 2 Quote:
Quote:


April 18, 2014, 09:19 

#4  
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Francisco Palacios
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Quote:
You are probably satisfying another criteria before arriving to the maximum number of iterations. Currently we SU2 have in place CAUCHY and RESIDUAL which are controlled by %  CONVERGENCE PARAMETERS % % % Convergence criteria (CAUCHY, RESIDUAL) % CONV_CRITERIA= RESIDUAL % % Residual reduction (order of magnitude with respect to the initial value) RESIDUAL_REDUCTION= 5 % % Min value of the residual (log10 of the residual) RESIDUAL_MINVAL= 8 % % Start convergence criteria at iteration number STARTCONV_ITER= 10 % % Number of elements to apply the criteria CAUCHY_ELEMS= 100 % % Epsilon to control the series convergence CAUCHY_EPS= 1E10 % % Direct function to apply the convergence criteria (LIFT, DRAG, NEARFIELD_PRESS) CAUCHY_FUNC_FLOW= DRAG Cheers, Francisco 

April 18, 2014, 10:55 

#5 
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Carlos Alexandre Tomigawa Aguni
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Hello Francisco! Thanks for your reply!
But the config files were supposed to work without any modification right? The thing is that with the same config the serial execution doesn't finishes and setting np = 2 it takes just few seconds to accomplish. Why is that? Thanks in advance. Carlos. 

April 24, 2014, 04:54 

#6 
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Thomas D. Economon
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Location: Stanford, CA
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Hi Carlos,
As Francisco mentions above, the simulation will terminate if any of the following criteria is met (whichever happens first): 1. The magnitude of the density residual drops the specified number of orders relative to the initial value, e.g., 2 > 7 if 5 orders reduction is requested 2. The density residual reaches the specified minimum value in RESIDUAL_MINVAL 3. The simulation hits the max number of allowed iterations in EXT_ITER Lastly, note that, depending on the chosen methods, the residual history will not be the same for serial and parallel calculations. This is likely why one of the conditions above is being met in serial and not in parallel, or viceversa. Hope this helps clear it up, Tom 

April 27, 2014, 23:21 

#7  
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Carlos Alexandre Tomigawa Aguni
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Quote:


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