  We follow a formalism presented by Kaiser to calculate the variance of bulk
flows in large scale surveys. We apply the formalism to a mock survey of Abell
clusters \'a la Lauer \& Postman and find the variance in the expected bulk
velocities in a universe with CDM, MDM and IRAS--QDOT power spectra. We
calculate the velocity variance as a function of the 1--D velocity dispersion
of the clusters and the size of the survey.

Astrophysics