Osmotic loading of a spherical gel may be analyzed by modeling the gel as a biphasic-solute material. In the paper that describes the implementation of biphasic-solute materials in FEBio (Finite element implementation of mechanochemical phenomena in neutral deformable porous media under finite deformation.
Ateshian GA, Albro MB, Maas S, Weiss JA. J Biomech Eng. 2011 Aug;133(8):081005.), this analysis is is performed using only one octant of a sphere, taking into account for symmetry about the coordinate planes. Despite this reduction in the mesh size, the analysis still requires several hours to complete.

Starting with FEBio 1.5.2, a new contact interface has been introduced (sliding-tension-compression) which makes it possible to define symmetry planes that are arbitrarily oriented. Using this feature, it is possible to reduce the representation of a sphere using azimuthal and elevational symmetry planes. The attached input (OsmoticLoadingSphericalGelFiniteSym.feb) illustrates this approach. The mesh was created on Cubit 13.2 and imported into PreView (via Abaqus format export/import). This mesh has only 30 elements for the sphere and the analysis completes in seconds.

Gerard