A novel microfluidic pump called bead mesopump was analyzed using numerical tools for performance predictions. An electrostatically actuated diaphragm produces pumping action, with appropriately placed inlet and outlet channels for flow rectification. For the first time ever, coupled, transient electrostatics-structures-flow simulations were successfully performed on this complex problem. Simulation data compare well with the available experimental test data. Simulations clearly show the presence of squeeze film flow, and its effects on actuation times and voltages. Simulations of different chamber and electrode designs were also completed to assess effects on pump performance. Numerical simulation tools for MEMS are thus shown to be of significant use in future for analysis of new pump designs, and device optimization.