Numerical Simulation of Fluid Induced Vibration of Graphenes at Micron Scales

Vibration of a single graphene and a pair of graphenes at micro meter scale induced by air flow is numerically simulated and examined by using a hybrid computational method starting from a microscopic level of description for the graphene. In order to bridge a huge gap in spatial and time scales in their motions, the carbon atoms of the graphene are represented by a small number of coarse grained particles, the fluid motion is described by the lattice Boltzmann equation and the momentum exchange at the boundary is treated by the time averaged immersed boundary method. It is found that a single graphene with attack angle 60 degrees and 90 degrees to the flow direction begins to bend downstream with oscillation after release and tends to attain an equilibrium form, but the oscillation amplitudes for 30 degrees increases in time. Also found is that when the separation distance of a pair of graphenes increases, the oscillation amplitudes become larger and chaotic and they collide each other, and the vorticity fields also tend to develop complex pattern. Strain distribution inside the graphene is also computed. Possibility to use the present system as a flow sensor and further development of the hybrid computational method are discussed.