  Ferrogels, i.e., hydrogels loaded with magnetic nanoparticles, have the
ability to deform in external magnetic fields. The precise shape of deformation
and the alignment of the gel in the field, however, depend on the interplay of
several factors. In this paper, we introduce a coarse-grained simulation model,
which takes into account the configuration of magnetic particles in the gel,
the sample shape, and aspects of the polymer network topology. We use this
model to show that in gels with an isotropic microstructure, an external
magnetic field reduces clustering, while this is not the case for uniaxial
gels, in which the particle configuration is anisotropic due to the presence of
a magnetic field during cross-linking. For ellipsoidal gels, we find that a
uniaxial microstructure additionally can override the deformation and alignment
expected as indicated the demagnetization energy. Finally, we examine to what
degree gels with different network topologies maintain the particle
microstructure ``frozen in`` during the cross-linking process.
