Number of particles inside the radius r_in against normalized radius r_in/r₀. This figure represents the fractal structure of the compressed aggregates in our simulation for various φ. We set a particle as an origin and count the number of particles inside r < r_in, where r is the distance from the origin to each particle’s center. Then we count the same correlation of all particles as an origin and take their average (similar figure of Fig. 7 in the paper of Wada et al. 2008). Each line shows the result at the different time steps. The solid thick lines represents the structure of fractal dimension D = 2, and dashed lines represent D = 3 for each corresponding φ. The dotted line shows the number of particles in calculation. The region below this line corresponds to inside the periodic boundaries.