Turbulence Specification Method for pressure outle

co2

I am modeling natural convection in a tank exposed to ambient conditions like sun radiation, ambient temp changes etc. The tank has an open opening at the top of physical diameter of 0.575 m

I know from my modeling results that there is a reverse flow in this pressure outlet. What will be the best method for Turbulence Specification Method at this pressure outlet ?

I am currently using tubulent intensity of 10% and hydruaulic dia of 0.575 m -- But I am not very happy with the results -- I am getting good convergence though -- Will changing Turbulence Specification Method help me in any way ?

looking forward to your answer!

Thanks! co2