A method for designing an absorbent article and evaluating its absorption behaviour is disclosed. A system using the method, is also disclosed. The method may be used for analyzing movement of a fluid in an absorbent article that comprises fluid-swellable composite material, to determine the performance of at least one feature of the absorbent article. The method includes inputting one or more properties for said fluid-swellable composite material 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 feature.