  The coupled evolution of an eroding cylinder immersed in a fluid within the
subcritical Reynolds range is explored with scale resolving simulations.
Erosion of the cylinder is driven by fluid shear stress. K\'arm\'an vortex
shedding features in the wake and these oscillations occur on a significantly
smaller time scale compared to the slowly eroding cylinder boundary. Temporal
and spatial averaging across the cylinder span allows mean wall statistics such
as wall shear to be evaluated; with geometry evolving in 2-D and the flow field
simulated in 3-D. The cylinder develops into a rounded triangular body with
uniform wall shear stress which is in agreement with existing theory and
experiments. We introduce a node shuffle algorithm to reposition nodes around
the cylinder boundary with a uniform distribution such that the mesh quality is
preserved under high boundary deformation. A cylinder is then modelled within
an infinite array of other cylinders by simulating a repeating unit cell and
their profile evolution is studied. A similar terminal form is discovered for
large cylinder spacings with consistent flow conditions and an intermediate
profile was found with a closely packed lattice before reaching the common
terminal form.
