that all these parameters can be adjusted to obtain a better agreement between our mass-loss predictions and the currently favoured observed rates. In particular, an increase in the carbon over helium ratio, a decrease in the stellar mass, an increase in the star’s luminosity, a decrease in its terminal flow velocity, or a more rapid wind acceleration, may all cause an increase of the mass-loss rate. The purpose of this study is, however, not to establish the optimum conditions for wind driving, but to create WR models with reasonable parameters, and to investigate the $Z$ effect on the mass-loss rate.

The predicted mass-loss rates {#s_massloss}
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The typical WN model
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We have used the method by Lucy & Abbott (1993), as shown in their Fig. 1, to search for the mass-loss rate. This mass-loss determination method yields rates that are globally consistent, and has been used for OB supergiants (Vink et al. 1999) and LBVs (Vink & de Koter 2002). Our typical WN model yields a mass-loss rate of log () $= -4.89$. This number is in fair agreement with observations. Clumping-corrected mass-loss rates for WN stars give values in the range $\log {\mbox{$\dot{M}$}}= -4.4$ to $-5.0$ (e.g. Nugis 