A 3D numerical study is carried out for a vertical direct chill (DC) rolling ingot caster for an aluminum alloy (AA-5052). The model incorporated the coupled turbulent melt flow and solidification aspects of the casting process. The caster consists of a low-head hot-top mold. The melt is assumed to have been delivered through the entire top cross section of the caster. The previously verified in-house computational fluid dynamics (CFD) code is used to investigate the effects of the important parameters such as casting speed, inlet melt superheat, and mold-metal contact effective heat transfer coefficient (HTC) on the low-head casting process. It is found that the sump depth (SD), liquid depth, and mushy thickness (MT) at the center of the ingot increase linearly with the casting speed while the shell thickness (ST) at the exit of the mold decreases linearly with the casting speed. Useful correlations concerning the above quantities with casting speed have been provided for the benefit of DC casting operators.