The impeller diameter/tank diameter ratio is 1/2. I am using a single reference frame approach to model impeller rotation (suitable for my geometry as there are no baffles).

I am using standard k-epsilon for an initial solution as it’s the most stable/reliable turbulence model (though not accurate for stirred tank reactors)

My issue is that the free surface shouldn’t be starting off from a flat liquid surface, then vortex develops and then later on in solution it returns to flat liquid surface. Rather the vortex will develop slowly over time from flat liquid surface to fully developed profile. I am using geo-reconstruct as many academic papers have used this to model free surface deformation with explicit VOF due to being most accurate,