Patent ID: 8498851

Claim:
A method for analyzing two-dimensional or three-dimensional movement of a fluid in an absorbent article that comprises fluid-swellable composite material, which comprises a fluid-swellable solid material, and that comprises void spaces in the fluid-swellable composite material, the fluid-swellable composite material being defined by a virtual two-dimensional or three-dimensional mesh, to determine performance or property of at least one feature of the absorbent article or the fluid-swellable composite material thereof, the method comprising: a) inputting one or more properties for the fluid-swellable composite material, or fluid-swellable solid material thereof, into a virtual model of the absorbent article; and b) evaluating, using a computer, the virtual model of the absorbent article to determine performance of the at least one feature of the absorbent article or fluid-swellable composite material thereof; the virtual model comprising a solution of the following equations: i) an equation for determining a liquid movement in void spaces, at a given location of the fluid-swellable composite material and/or at a given time; ii) an equation for determining an amount of liquid present in the fluid-swellable solid material, at a given location of the fluid-swellable composite material and/or at a given time; and iii) an equation for determining displacement of one or more locations or the mesh of the fluid-swellable composite material, due to swelling of the material, at a given time, wherein a solution of the equations is described by the following: ɛ ⁢ ∂ s l ⁢ ( Ψ l ) ∂ t + ɛ ⁢ ⁢ s l ⁢ γ _ ⁢ ∂ Ψ l ∂ t - ∇ · [ k r l ⁢ K ( ⁢ ∇ Ψ l + e ) ] = ⁢ - [ 1 ρ o l ⁢ C _ AGMo s J s + ɛ ⁢ ∂ s l ∂ m 2 s + s l ( ⁢ ∂ ɛ ∂ m 2 s + ɛ J s ⁢ ∂ J s ∂ m 2 s ) ] ⁢ ∂ m 2 s ∂ t - 1 ρ o l ⁢ ϕ s ⁡ ( u s ) - ϕ l ⁡ ( u s ) ⁢ ⁢ ∂ C _ L → So s ∂ t = τ ⁢ ⁢ a sl ⁡ ( s ^ ⁡ ( s e l ) ) ⁢ m ^ 2 s ⁢ C _ AGMo s - J s ⁢ ϕ s ⁡ ( u s ) ⁢ ⁢ ∇ · u s = d s wherein s 1 =saturation, t=time, k 1 r=relative permeability, K=hydraulic conductive tensor, e=elemental, C S AGM=concentration fluid-swellable solid material, j s =jacobian of solid domain, m s 2 =AGM x-load, u s =displacement vector, d s =scalar solid strain, a s1 =saturation-dependent fraction, C L =liquid concentration; and are used to develop an absorbent article.