The cluster velocity field in CDM-like models

We study the large-scale velocity fields traced by galaxy clusters in numerical simulations, which are based on the Zel'dovich approximation (ZA). Their properties are compared to those measured for available observational data of cluster peculiar velocities. In order to address the problem of the reliability of our ZA simulations, we compare their cluster velocity field with that coming from "exact" N-body simulations. We perform simulations of CDM models, with different values of the density parameter in the range 0.2 less than or equal to Omega(0) less than or equal to 1, either with and without the cosmological constant term providing a flat geometry. We also simulate a Cold+Hot Dark Matter (CHDM) model, with Omega(hot) = 0.3 provided by the hot component. The adopted box-size is 960 h(-1) Mpc. Cluster velocity fields are studied by using the cumulative velocity probability function and the bulk flow statistics. As a result we find that open CDM models with Omega(0) less than or equal to 0.4 and flat CDM models with Omega(0) less than or equal to 0.2 are ruled out. Both CHDM and CDM with Omega(0) = 1 are acceptable, although the former performs marginally better.