
[Sponsors] 
April 16, 2014, 21:04 
[Tutorial 3] Doubts about iteration number

#1 
Member
Carlos Alexandre Tomigawa Aguni
Join Date: Mar 2014
Posts: 40
Rep Power: 11 
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 23:09. 

April 16, 2014, 21:24 

#2 
Member
Carlos Alexandre Tomigawa Aguni
Join Date: Mar 2014
Posts: 40
Rep Power: 11 
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, 23:19 

#3  
Member
Carlos Alexandre Tomigawa Aguni
Join Date: Mar 2014
Posts: 40
Rep Power: 11 
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, 10:19 

#4  
Super Moderator
Francisco Palacios
Join Date: Jan 2013
Location: Long Beach, CA
Posts: 404
Rep Power: 15 
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, 11:55 

#5 
Member
Carlos Alexandre Tomigawa Aguni
Join Date: Mar 2014
Posts: 40
Rep Power: 11 
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, 05:54 

#6 
Super Moderator
Thomas D. Economon
Join Date: Jan 2013
Location: Stanford, CA
Posts: 271
Rep Power: 14 
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 28, 2014, 00:21 

#7  
Member
Carlos Alexandre Tomigawa Aguni
Join Date: Mar 2014
Posts: 40
Rep Power: 11 
Quote:


Thread Tools  Search this Thread 
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Foam::error::PrintStack  almir  OpenFOAM Running, Solving & CFD  91  December 21, 2022 05:50 
mesh file for flow over a circular cylinder  Ardalan  Main CFD Forum  7  December 15, 2020 14:06 
Iteration number for junction box routine  Allan  CFX  8  March 8, 2018 07:55 
[snappyHexMesh] external flow with snappyHexMesh  chelvistero  OpenFOAM Meshing & Mesh Conversion  11  January 15, 2010 20:43 
Parallel runs slower with MTU=9000 than MTU=1500  Javier Larrondo  FLUENT  0  October 28, 2007 23:30 