Comparison of the expanding lines for clusters with and without fractalization. The settings for other parameters are the same as described in Sec. 2.1. We arranged a fractal distribution of stars within a sphere of constant average density, following a similar method as outlined in Goodwin & Whitworth (2004). The likelihood of a sub-box receiving a star can be represented by 2^D–3, where D represents the fractal dimension. When D is set to 3.0, there is no fractality observed since the probability becomes one. More details can be found in Küpper et al. (2011) and the user manual for the McLuster code.