In two types of helium-nanotube setups, no coherent transmission of mechanical energy occurred in classical MD simulations. The fluid motion thermalized too rapidly to allow this to happen. This occurred despite the fact that conditions were made as favorable as possible for energy transmission (low temperatures, static nanotubes, near liquid densities). We emphasize that MD simulation has worked well to predict some fluid properties such as viscosity and diffusion coefficient. However, it appears to be unsuitable for the study of phenomena requiring coherent fluid motion. Because of the inherent mechanical constraints, classical MD treatments may suffice for similar studies in solid nanostructures, depending on the degree of external mechanical constraints. To what extent shock and pressure wave propagation occurs in nano-fluidic systems cannot be determined by classical simulation, nor has it been studied experimentally. If, in the future, such behavior were observed, a quantum mechanical treatment or some other method would be required for explanation.
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