Numerical simulations using non-commercial OpenFOAM software were performed and compared with experimental data. The experiment consisted in pumping dense fluid (saline solution of sodium chloride and food dye) into a tank with a less dense fluid (fresh water) next to the bottom of the tank. The released fluid dilutes similarly to real cases of gas dispersion governed by buoyancy forces. Reynolds Averaged Navier-Stokes (RANS) approach with k-ω SST model was applied to simulate three experimental cases with different initial conditions. The results were compared qualitatively and numerically concerning the height (h_t) of the dense layer and its velocity profile. The numerical findings agree with the experimental data.