Try to run simulation with out including energy eqyation for first 50 iteration then re activate energy equation

Divergence in Algebraic Multi Grid (AMG) solver is a common problem when the used under relaxation factors (URF) are so high that it makes the individual cells imbalance of any field properties or when some cells are not suitable for the physical problem..

Solution: try to reduce the URFs slowly (momentum or pressure) then run the simulation with out initialising , if you are still getting the same problem, then change those cells by checking the contour of residual .

Thank you....

Yes it is the Algebraic Multi Grid (AMG) solver problem .You can also check you dimensions of you mesh .