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-   -   divergence detected in AMG solver (http://www.cfd-online.com/Forums/fluent/41842-divergence-detected-amg-solver.html)

selvaganesh July 26, 2006 02:02

divergence detected in AMG solver
 
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

aleni32 January 31, 2014 23:53

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.

lehoanganh07 February 1, 2014 00:04

Check your mesh which is allway the cause

neprendo February 5, 2014 04:20

Quote:

Originally Posted by lehoanganh07 (Post 472850)
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

Nick

neprendo February 5, 2014 04:49

Quote:

Originally Posted by lehoanganh07 (Post 472850)
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

Nick

atulurade February 5, 2014 04:55

during using solver at start reduce the under relaxation factor . it will solve your problem of divergence ..


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