Cooling mechanisms and inversed flow in cylindroco

Andreas

Hi,

I am using Fluent to simulate the cooling mechanisms in cylindroconical tanks applying heat flux and adiabatic as BC. Therefore I investigate the flow behaviour of water depending on natural convection using the Boussinesq Approximation for linear temperature dependence of density.

How can I consider the flow inversion that appears while cooling below 4 degrees (anomalous behaviour of water)? First I supposed it is due to the Boussinesq-Model but I also defined a polynomial profile of temperature as density-temperature dependence and obtained no better physical explainable results. That means the density does not decrease after reaching the 4 degree level and therefore the flow does not inverse direction.

Thanks for helping me.

Andreas