The performance of a proton exchange membrane (PEM) fuel cell strongly depends on the nature of reactant distribution and the effectiveness of liquid water removal. In this work, three different configurations of a mixed flow distributor are studied analytically and numerically to find out the effect of nonuniform under-rib convection on reactant and liquid water distribution in the cell. In a mixed flow distributor, the rate of under-rib convection is found to be different under each rib in the same flow sector which results in different rates of removal of liquid water. This helps to retain some water to hydrate the membrane, whereas the excess is removed to avoid flooding. It is found that under-rib convection aids to get better reactant distribution, reduces pressure drop, and provides better control over liquid water removal which is helpful in developing efficient water management strategies for PEM fuel cells. Copyright © 2015 by ASME.