  The study of dynamical properties of Galactic open clusters is a fundamental
prerequisite for the comprehension of their dissolution processes. In this
work, we characterized 12 open clusters, namely: Collinder 258, NGC 6756,
Czernik 37, NGC 5381, Ruprecht 111, Ruprecht 102, NGC 6249, Basel 5, Ruprecht
97, Trumpler 25, ESO 129-SC32 and BH 150, projected against dense stellar
fields. In order to do that, we employed Washington $CT_{1}$ photometry and
GAIA DR2 astrometry, combined with a decontamination algorithm applied to the
three-dimensional astrometric space of proper motions and parallaxes. From the
derived membership likelihoods, we built decontaminated colour-magnitude
diagrams, while structural parameters were obtained from King profiles fitting.
Our analysis revealed that they are relatively young open clusters (log($t$
yr$^{-1}$) $\sim7.3-8.6$), placed along the Sagittarius spiral arm, and at
different internal dynamical stages. We found that the half-light radius to
Jacobi radius ratio, the concentration parameter and the age to relaxation time
ratio describe satisfactorily their different stages of dynamical evolution.
Those relative more dynamically evolved open clusters have apparently
experienced more important low-mass star loss.
