Molecular Dynamics Simulation of the Nanofluidic Energy Absorption System Under Mid-speed Loading

In this work, a nanofluidic energy absorption system (NEAS) under mid-speed loading is investigated by using molecular dynamics simulation. Usually, two types of dynamic and quasi-static loadings have been applied on NEAS. In the dynamic loadings, NEAS is taken under high-speed loadings in the range of 5 m/s up to 1000 m/s, and in the quasi-static loadings, it is taken under low-speed loadings in the range of less than or equal to 0.0005 m/s. Here, to investigate the performance of NEAS under mid-speed loading, four loading rates of 0.2, 0.4, 0.8 and 1.0 m/s are considered. Also, four armchair CNTs (8,8), (10,10), (12,12) and (14,14) were selected to study the effects of nanotube size. The results of simulations showed that contact angle which shows the hydrophobicity of carbon nanotube (CNT) is reduced on average 3.6% by increasing the loading rate in all CNTs, leading to an average 41.7% decrease of infiltration pressure and an average 16% reduction of absorbed energy density in all CNTs. No friction is observed at the loading rate of 0.2 m/s in all CNTs during movement of water molecules in CNT. But, at the other loading rates, friction is increased by increasing the loading rate, leading to an average 24.8% reduction of the absorbed energy efficiency of NEAS in all CNTs. Also, contact angle, infiltration pressure, absorbed energy density and efficiency are decreased by increasing the CNT diameter.