The limiting permeation flux and the cake resistance are determined during ultrafiltration experiments of a low concentrated suspension of glass microparticles at a plane ceramic membrane surface for three inlet and outlet configurations with different forms and cross sections. The limiting permeation flux values are analyzed in view of wall shear rates local values obtained in previous work.([1]) The ratio of the inlet velocity to the mean tangential one appears to be a key parameter for understanding the performance of the ultrafiltration process. Indeed, a ratio value different from 1 leads to an increace of the limiting permeation flux and a decrease of the specific energy consumption. Furthermore, it seems that the limiting permeation flux value depends not only on the wall shear stress values, but also on the granulometric distribution of the deposit.