This chapter summarizes some important models and numerical studies for several types of steady flows commonly investigated in the literature. Dynamics of grain and power flows has been extensively investigated for their common appearances in industrial processes and natural events. For certain types of flows, a similarity solution may be found, and numerical solution can always be sought for more complex cases. This scheme succeeded in capturing the primary mode of bulk dynamics in several surface flow problems. When a granular assembly moves fast at dilute to moderate solid volume concentration, most particle particle interactions are uncorrelated repulsive binary collisions with contact durations much shorter than the timescale associated with bulk shear rate. Such flow is known as a rapid granular flow in collisional regime. Like dry granular materials, the dynamics of cohesive grain assembly has been investigated through particle-based simulation by adding new interaction forces to the contact model.