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divergence detected in AMG solver

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Old   July 26, 2006, 02:02
Default divergence detected in AMG solver
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selvaganesh
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i am calculating turbulent viscosity which includes damping function using UDF. when i hook this udf and when iterating it gives "deivergence detected in AMG solver in x momentum. how can i solve my problem plz somebody help me
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Old   January 31, 2014, 23:53
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I have same problem but after 3 second the divergence in AMG solver happens. please help me(I reduced URF of my UDF but it didnt worked.
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Old   February 1, 2014, 00:04
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le hoang anh
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Check your mesh which is allway the cause
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Old   February 5, 2014, 04:20
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Nick Prendergast
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Quote:
Originally Posted by lehoanganh07 View Post
Check your mesh which is allway the cause
I would say incorrect boundary conditions can also cause divergence.

and as a another point, if you're using an explicit transient solver you need to ensure that c= (velocity*delta t)/delta x is less than or equal to 1 for stability, definitely affect convergence.

and this should help troubleshoot your model:
http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

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Old   February 5, 2014, 04:49
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Quote:
Originally Posted by lehoanganh07 View Post
Check your mesh which is allway the cause
I would say incorrect boundary conditions can also cause divergence.

and as a another point, if you're using an explicit transient solver you need to ensure that c= (velocity*delta t)/delta x is less than or equal to 1 for stability, definitely affect convergence.

and this should help troubleshoot your model:
http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F

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Old   February 5, 2014, 04:55
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during using solver at start reduce the under relaxation factor . it will solve your problem of divergence ..
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