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]

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]

Check your mesh which is allway the cause

[neprendo]

Originally Posted by lehoanganh07

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]

Originally Posted by lehoanganh07

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]

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