1. A method for analyzing movement of a fluid in an absorbent article that comprises fluid-swellable composite material, which comprises a fluid-swellable solid material, to determine the performance of at least one feature of the absorbent article, said method comprising: inputting one or more properties for said fluid-swellable composite material or fluid-swellable solid material thereof into a virtual model of the absorbent article to produce a representation of at least one feature of the absorbent article; and evaluating the virtual model of the absorbent article to determine the performance of the at least one feature of the absorbent article.