This study reports on the output linear density that was attained by simulation for various levels of draft roller gauge and draft ratio, based on the dynamic model with approximated sinusoidal velocity variance model to specific fiber length distributions to test the model feasibility, while a random variation for the input bundle linear density was provided. Results from model simulation showed that a process resonance could take place, when the draft roller gauge or draft ratio reached the critical values, because there were fundamental frequencies which spread in the irregularity of the bundle linear density, giving rise to some resonance. Thus, the irregularity of the output linear density began increasing steeply. From the view point of the output linear density as a whole, the irregularity decreased, as the draft roller gauge increased. A process resonance occurred in the range of draft roller gauge between 1.25 and 1.5 multitudes of the (maximal) fiber length. Length distribution led to a lower fundamental frequency (longer fundamental wavelength) than the uniform fiber length. High draft ratio yielded high irregularity in the output bundle. Especially, the process resonance occurred between the draft ratio 20 and 30. In the draft ratio range higher than 30, the output included wide-ranged regularly oscillatory components of irregularity that corresponded to the integer-multiple of the fundamental frequency, which shifted to a higher value, when the fiber length was distributed. In addition, the approximated sinusoidal velocity variance model turned out to be adequate to estimate the irregularity of the bundle linear density with both the uniform and the quadratic fiber length distribution.