Radial velocity distribution of cool gas in clusters within 2R_200c from TNG300 and TNG-Cluster at z = 0. Each panel shows the velocity distribution of cool gas cells for every cluster weighted by the mass of each gas cell, in seven cluster mass bins of 0.2 dex. The faint colored lines show the velocity distribution of individual clusters and the solid (dashed) black line shows the mean (median) of the mass bin. The last panel shows the distribution of all clusters. Negative velocity denotes gas moving toward the cluster center (inflowing), positive velocity denotes gas moving away from the cluster center (outflowing). The individual distribution lines are colored according to the host cluster mass: An orange color denotes a mass near the high edge of the mass bin, a purple color a mass near the low edge of the mass bin. The gray solid line marks the position of v_r = 0; the label to either side denote the mean fraction of gas mass to the left (negative velocity, infalling) and right (positive velocity, outflowing) of the zero line. The gray dashed line marks the position of the negative of the mean virial velocity in the mass bin. The cool gas in clusters is predominantly infalling, i.e. inflowing toward the center.