  Coronal Mass Ejections (CMEs) are large-scale eruptions from the Sun into
interplanetary space. Despite being major space weather drivers, our knowledge
of the CME properties in the inner heliosphere remains constrained by the
scarcity of observations at distances other than 1 au. Furthermore, most CMEs
are observed in situ by single spacecraft, requiring numerical models to
complement the sparse observations available. We aim to assess the ability of
the linear force-free spheromak CME model in EUHFORIA to describe the radial
evolution of interplanetary CMEs, yielding new context for observational
studies. We model one well-studied CME, and investigate its radial evolution by
placing virtual spacecraft along the Sun-Earth line in the simulation domain.
To directly compare observational and modelling results, we characterise the
interplanetary CME signatures between 0.2 and 1.9 au from modelled time series,
exploiting techniques traditionally employed to analyse real in situ data.
Results show that the modelled radial evolution of the mean solar wind and CME
values is consistent with observational and theoretical expectations. The CME
expands as a consequence of the decaying pressure in the surrounding wind: the
expansion is rapid within 0.4 au, and moderate at larger distances. The early
rapid expansion could not explain the overestimated CME radial size in our
simulation, suggesting this is an intrinsic limitation of the spheromak
geometry used. The magnetic field profile indicates a relaxation of the CME
during propagation, while ageing is most probably not a substantial source of
magnetic asymmetry beyond 0.4 au. We also report a CME wake that is
significantly shorter than suggested by observations. Overall, EUHFORIA
provides a consistent description of the radial evolution of solar wind and
CMEs; nevertheless, improvements are required to better reproduce the CME
radial extension.
