Simulation of a HSS in the inner heliosphere, derived by the EUHFORIA MHD code. (a) and (b) Snapshots of the radial velocity distribution in the solar equatorial and meridional plane. (c) Snapshot of the properties of the HSS along a radial direction in the equatorial plane: radial velocity component (black), density (orange), temperature (red), and longitudinal angle of the flow velocity to the radial direction (gray). The gray dashed horizontal line corresponds to a longitudinal angle of 0°, i.e., a perfect radial flow. The black vertical line marks the position of the stream interface between the HSS and the preceding slow solar wind stream.