  Given their strong stellar winds, Wolf-Rayet (WR) stars exhibit emission line
spectra that are predominantly formed in expanding atmospheric layers. The
description of the wind velocity field $v(r)$ is therefore a crucial ingredient
in the spectral analysis of WR stars, possibly influencing the determination of
stellar parameters. In view of this, we perform a systematic study by
simulating a sequence of WR-star spectra for different temperatures and
mass-loss rates using $\beta$-type laws with $0.5\leq\beta\leq 20$. We quantify
the impact of varying $v(r)$ by analysing diagnostic lines and spectral
classifications of emergent model spectra computed with the Potsdam Wolf-Rayet
(PoWR) code. We additionally cross-check these models with hydrodynamically
consistent -- hydro -- model atmospheres. Our analysis confirms that the choice
of the $\beta$-exponent has a strong impact on WR-star spectra, affecting line
widths, line strengths and line profiles. In some parameter regimes, the entire
range of WR subtypes could be covered. Comparison with observed WR stars and
hydro models revealed that values of $\beta \gtrsim 8$ are unlikely to be
realized in nature, but a range of $\beta$-values needs to be considered in
spectral analysis. UV spectroscopy is crucial here to avoid an underestimation
of the terminal velocity $v_\infty$. Neither single- nor double-$\beta$
descriptions yield an acceptable approximation of the inner wind when compared
to hydro models. Instead, we find temperature shifts to lower $T_{2/3}$ when
employing a hydro model. Additionally, there are further hints that round-lined
profiles seen in several early WN stars are an effect from non-$\beta$ velocity
laws.
