  In this paper we show how non-radial motions, originating from the tidal
interaction of the irregular mass distribution within and around protoclusters,
can solve some of the problems of the CDM model. Firstly the discrepancy
between the CDM predicted two-points correlation function of clusters and the
observed one. We compare the two-points correlation function, that we obtain
taking account of non-radial motions, with that obtained by Sutherland &
Efstathiou (1991) from the analysis of Geller & Hucra's (1988) deep redshift
survey and with the data points for the APM clusters obtained by Efstathiou et
al. (1992). Secondly the problem of the X-ray clusters abundance
over-production predicted by the CDM model. In this case we compare the X-ray
temperature distribution function, calculated using Press-Schechter theory and
Evrard's (1990) prescriptions for the mass-temperature relation, taking also
account of the non-radial motions, with Henry & Arnaud (1991) and Edge et al.
(1990) X-ray temperature distributions for local clusters. We find that in both
cases the model is in good agreement with experimental data. Finally we
calculate the bias coefficient using a selection function that takes into
account the effects of non-radial motions, and we show that the bias so
obtained can account for a substantial part of the total bias required by
observations on cluster scales.
