[harsha1988]

hello,
I am trying to solve a flow through shell and tube with solidification/melting,phase change material in shell and fluid flow through tube. This is a 2D axisymmetric problem.
I created my model starting on X axis (as this has to be the direction of rotation). If I Name this as Axis,i cannot provide a convective boundary condition here,if i dont name the axis boundary Fluent throws " Divergence detected in AMG solver:Temperature" error.

Can someone please guide me,how to provide axis of rotation boundary. or share a geometry of a typical axisymetric cylinder.

[CeesH]

Is the axis still an axis condition when you don't name it such? Or does it become a wall? Of course, you should not have to provide a condition at the axis - it's already fully defined.

What I would advice is to do a mesh check when the axis is set properly. Does the mesh check give a good outcome or does it fail? To me, it sounds like the axis of your geometry may not agree exactly with the x-axis of your coordinate system. If that is indeed the case, the axisymmetric approach will not work since there is a gap in the center (even if the gap is femtometer size or so, it will crash). If this is indeed the case, the mesh check will fail and give you advice on how to fix the situation. Follow the advice, and you should be good to go.

Cees

[harsha1988]

Hello,
Thanks for the reply. I modeled using con incidence constraint with x axis to make sure there is no issue of axis coincidence with x axis.
Now the case is running,but I get a "divergence detected temperature-increasing relaxation sweeps" after about 600 iterations.

If I get through this i think there might be a convergence.Can someone please help how to get rid of this error.