  The effect of viscosity and of converging flows on the formation of blobs in
the slow solar wind is analysed by means of resistive MHD simulations. The
regions above coronal streamers where blobs are formed (Sheeley et al., 1997)
are simulated using a model previously proposed by Einaudi et al. (1999). The
result of our investigation is twofold. First, we demonstrate a new mechanism
for enhanced momentum transfer between a forming blob and the fast solar wind
surrounding it. The effect is caused by the longer range of the electric field
caused by the tearing instability forming the blob. The electric field reaches
into the fast solar wind and interacts with it, causing a viscous drag that is
global in nature rather than local across fluid layers as it is the case in
normal uncharged fluids (like water). Second, the presence of a magnetic cusp
at the tip of a coronal helmet streamer causes a converging of the flows on the
two sides of the streamer and a direct push of the forming island by the fast
solar wind, resulting in a more efficient momentum exchange.
