Natural Heat Convection - Solution not converged

I am trying to solve a simple problem of natural heat convection in water. It is a 2D problem . Two faces are kept at 300K and 310 K. Dimensions are 1 and .6 m . I have connected both heat and flow modules. I am getting an error stating that the solution has not converged.I am new to comsol. How can I solve this problem.

I have made the mesh finer.