This paper presents the results of high-fidelity, 3-D simulations of coupled flow, heat-transfer and structural mechanics simulations of microchannels, micropumps, microvalves, and time-accurate simulations of a microoscillator. In each of these cases, the simulated results were compared with experimental and/or other published data, with excellent agreement. These results demonstrate the capabilities, accuracy and speed of the simulation tools for predictions of coupled, complex multi-physics processes in MEMS devices and their utility during the design phases of these devices for optimization and performance prediction.