$\newcommand{\Dev}{\operatorname{Dev}}$ $\newcommand{\dev}{\operatorname{dev}}$ $\newcommand{\grad}{\operatorname{grad}}$ $\newcommand{\divg}{\operatorname{div}}$ $\newcommand{\Ei}{\operatorname{Ei}}$ $\newcommand{\tr}{\operatorname{tr}}$

When a multiphasic material is initially exposed to a given external environment with effective pressure $\tilde{p}_{\ast}$ and effective concentrations $\tilde{c}_{\ast}^{\alpha}$ , the initial conditions inside the material should be set to $\tilde{p}=\tilde{p}_{\ast}$ and $\tilde{c}^{\alpha}=\tilde{c}_{\ast}^{\alpha}$ in order to expedite the evaluation of the initial state of swelling. The values of $\tilde{p}_{\ast}$ and $\tilde{c}_{\ast}^{\alpha}$ should be evaluated as described in Section 8.6.2↑.