  We discuss how to use the Rees-Sciama (RS) effect associated with merging
clusters of galaxies to measure their kinematic properties. In a previous work
(Rubino-Martin et al. 2004), the morphology and symmetries of the effect were
examined by means of a simplified model. Here, we use realistic N-body
simulations to better describe the effect, and to confirm that the signal has a
characteristic quadrupole structure. From the amplitude of the signal obtained,
we conclude that it is necessary to combine several cluster mergers in order to
achieve a detection. Using the extended Press-Schechter formalism, we
characterized the expected distribution of the parameters describing the
mergers, and we used these results to generate realistic mock catalogues of
cluster mergers. To optimize the extraction of the RS signal, we developed an
extension of the spatial filtering method described in Haehnelt & Tegmark
(1996). This extended filter has a general definition, so it can be applied in
many other fields, such as gravitational lensing of the CMB or lensing of
background galaxies. It has been applied to our mock catalogues, and we show
that with the announced sensitivities of future experiments like the Atacama
Cosmology Telescope (ACT), the South Pole Telescope (SPT) or the Atacama Large
Millimeter Array (ALMA), a detection of the signal will be possible if we
consider of the order of 1,000 cluster mergers.
