Steady dynamical behaviors of novel viscous pump with groove under the rotor

A novel viscous pump with groove under the rotor in straight channel is first analyzed, and associated flow dynamic behaviors and characteristics are numerically investigated by 2-D laminar model. As Reynolds number rises, the vortices near the rotor become asymmetrical and larger, and then the dimensionless flow flux drops, while the dimensionless driving power rises. The groove height can also play an important role in the dynamical performance of the viscous pump. As the groove height increases, the dimensionless flow flux will first increase and then decrease, and it reaches maximum with optimal groove height. For small groove height, the flow passage with positive x-velocity is extended near the rotor, so the flow flux increases with groove height. For large groove height, the vortices in the upstream and downstream regions can combine into one large vortex, and the flow flux is obviously reduced. The driving power also affects the dynamic performance of viscous pump, and it is dependent upon the wall shear stresses at the rotor interface. In the narrow gap between the groove and rotor, thin film flow exists, so the wall shear stresses adjacent to the groove are much larger than those away from the groove, and the shear stresses will reach maximum near the groove edge. As a result, the dimensionless driving power of rotor will increase with the groove height but decrease with the gap width.