Most experimental efforts have been focused on the prediction of the initial locus of the material that is extracted from a single aperture. Such a locus is named the ‘‘drawbody’’ or isolated extracted zone (IEZ) and depends mainly on the volume of the extracted material. However, little progress has been achieved in predicting the IEZ from first principles. To date, the mathematical equation that best describes the shape of the extraction drawbody is the Bergmark–Roos equation. In addition, due to the lack of both analytical models and reliable experimental data, the flow resulting from interactions of several drawpoints is completely unknown. Thus, in this complex situation, the locus of extracted material is roughly estimated by the elementary geometrical superposition of IEZs produced by the drawpoints under study.