Stability and dynamic characteristics of rough nanotubes conveying nanoflow

In this paper, a theoretical model is developed to describe the comprehensive influences of surface roughness, fluid rarefication and nonlocal effect on the instability and dynamic behaviors of rough nanotubes conveying nanoflow. Correction factors for fluid are utilized to characterize the effects of the surface roughness and Knudsen number on the internal fluid. The results demonstrate that the surface roughness of nanotube and rarefication effect of nanoflow have opposite influences on the stability and natural frequencies of the system. For fixed-fixed nanotubes, as the roughness height increases, the critical flow velocity increases. On the other hand, as the Knudsen number increases, which indicates the rarefication effect dominates, the critical velocity decreases. In addition, with the increasing of roughness height or the decreasing of Knudsen number, the natural frequency of the first mode increases. For cantilevered nanotubes, the surface roughness makes the curve, which describes the relationship between the critical velocity and the mass ratio, move to the top right of the critical velocity-mass ratio plane while the rarefication effect induces the curve shifting to the bottom left. In addition, the influences of nonlocal effect are also analyzed and discussed. The material length scale parameter can enhance the stiffness of nanotube and increase the critical velocity.