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November 8, 2010, 17:49 
Particle fate "Integration error"

#1 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,638
Rep Power: 98 
Time for me to ask a question for a change
I am doing a particle tracking simulation and I am getting almost half my particle tracks end with fate "Integration error". So far I have not been able to find what the problem is. Does anybody know what is causing this or how to fix it?
Code:
======================================================================  Timestepping Information    Timestep  RMS Courant Number  Max Courant Number  ++++  5.0000E05  1.49  16.88   ====================================================================== TIME STEP = 865 SIMULATION TIME = 4.3250E02 CPU SECONDS = 1.095E+05  COEFFICIENT LOOP ITERATION = 1 CPU SECONDS = 1.095E+05   Equation  Rate  RMS Res  Max Res  Linear Solution  ++++++  UMom  0.98  9.3E05  8.2E03  1.6E02 OK  VMom  0.99  1.0E04  4.8E03  2.6E02 OK  WMom  0.98  1.1E04  6.6E03  1.8E02 OK  PMass  0.97  2.2E05  2.7E03  5.1 9.4E02 OK ++++++  COEFFICIENT LOOP ITERATION = 2 CPU SECONDS = 1.095E+05   Equation  Rate  RMS Res  Max Res  Linear Solution  ++++++  UMom  0.41  3.8E05  3.9E03  4.0E03 OK  VMom  0.60  6.2E05  4.7E03  4.0E03 OK  WMom  0.63  6.9E05  3.8E03  4.0E03 OK  PMass  0.60  1.4E05  2.2E03  9.2 4.3E02 OK ++++++ ====================================================================== Particle Diagnostics ====================================================================== ++  Particle Fate Diagnostics  ++  Particle type  Fate type Particles  ++  Ink  Entered domain : 2560    Continue from last time step : 10676    Left domain : 1    Collected on walls : 1361    Waiting for next time step : 10669    Integration error : 1205  ++ 

November 10, 2010, 12:25 

#2 
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Bharath kumar
Join Date: Apr 2009
Posts: 168
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hi ghorrocks,
the reason may be if the particles trapped in recirculation zone for a long time this kind of error occur otherwise the time step won't suits well for the problem. 

November 10, 2010, 17:27 

#3 
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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I see. There are no recirculations where the particles are travelling, but I do have an unusually small geometry. I will look into tolerances on minimum particle movements.
Thanks for the tip! 

March 11, 2011, 14:57 

#4 
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Join Date: Jun 2010
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Hi ghorrocks
Increasing the value of "number of integration steps per element" could help. Integration error problem solved by that way in my case. It appears it's late response for your work but it may help others 

March 13, 2011, 06:38 

#5 
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 12,638
Rep Power: 98 
Thanks for the comment. I had not tried that one.
But unfortunately that piece of work is long finished and I doubt I will get to play with it again. But you never know. 

December 13, 2011, 12:03 

#6  
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Julian Krick
Join Date: May 2009
Location: Guelph
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Quote:
mnis = nsipe * "number of elements a particle travels through" Thus, if nispe = 1e3 and mnis = 1e6, a particle can travel trough 1e3 elements, before it "Exceeded Integration Limit". Another reason for a high number of particle loss due to an "Integration Error", may be that the initial velocity of the particles is set to zero. I released particles from a sphere with a velocity of 0 m/s and ca. 50% of the particles got lost due to an integration error. After assigning an initial velocity of 1 m/s, no particles experienced this error.
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grid generation: ICEM CFD 13.0 solver: CFX 13.0 

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