[yhs0365]

hello everyone

I am having trouble with solving simple natural convection problem.

The problem is that momentum residual is so high and do not go down...

I attached my design image... the red one is heat source so maybe there has to be movement of inner gas, circulation around heat source

design.jpg

When I set laminar model and set initial velocity as 0m/s momentum residual was as below momentum residual.png

and velocity profile was very dirty...

for example region that has to be have downstream had upstream and so on...

so i ask for colleague how to reduce momentum residual he said that I have to change turbulence model or set initial velocity as twice of my goal velocity

so I set k-e model (because it's residual was lower than sst) and set initial velocity as 0.1m/s.

then, momentum and turbulence residual were as below

momentum residual-2.jpg
turbulence residual-2.jpg

velocity profile was clearer than before but, still momentum residual has to be lower and velocity profile was still incorrect.

is there somebody know well about natural convection?
and is there other factors to lower momentum residual and make clear velocity profile??

thank u!