Modelling water heating in a constant volume tank
 

Description:
-cylindrical water tank
-water heated by positive heat flux segments (each segment is defined by a time-dependent UDF)
-expect natural convection / buoyancy driven upward flow near walls
-2D axisymmetric

Geometry:
See Picture

Settings:
-Boussinesq approx for variable density
-transient (unsteady) simulation
-pressure-based solver
-laminar flow model

Problems:
-not getting good convergence (usually the continuity residual)
-velocities leaving the top and/or bottom boundaries: See Picture

This seems like a simple case to simulate, but I've been struggling to get this to work for a while. I would appreciate any help with troubleshooting/debugging!

(Let me know for more information)

If you have solved the problem, can you tell me how? I have a similar water heating problem but it seems the water doesnt reach equilibrium temperature even after large number of timesteps