  The filamentary nature of accretion streams found around embedded sources
suggest that protostellar disks experience heterogenous infall from the
star-forming environment, consistent with the accretion behavior onto
star-forming cores in top-down star-cluster formation simulations. This may
produce disk substructures in the form of rings, gaps, and spirals continuing
to be identified by high-resolution imaging surveys in both embedded Class 0/I
and later Class II sources. We present a parameter study of anisotropic infall,
informed by the properties of accretion flows onto protostellar cores in
numerical simulations, and varying the relative specific angular momentum of
incoming flows as well as their flow geometry. Our results show that
anisotropic infall perturbs the disk and readily launches the Rossby wave
instability (RWI). It forms vortices at the inner and outer edge of the infall
zone where material is deposited. These vortices drive spiral waves and angular
momentum transport, with some models able to drive stresses corresponding to a
viscosity parameter on the order of $\alpha \sim 10^{-2}$. The resulting
azimuthal shear forms robust pressure bumps that act as barriers to radial
drift of dust grains, as demonstrated by post-processing calculations of
drift-dominated dust evolution. We discuss how a self-consistent model of
anisotropic infall can account for the formation of millimeter rings in the
outer disk as well as producing compact dust disks, consistent with
observations of embedded sources.
