Anomalous behavior of fluid flow through thin carbon nanotubes

M Rezaee and H Ghassemi, THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS, 34, 177-186 (2020).

DOI: 10.1007/s00162-020-00521-3

Molecular dynamics simulation is used to study flow rate behavior of monoatomic fluid through carbon nanotube (CNT) against the pore diameter. All armchair and zigzag CNTs with diameters below 1.5 nm were considered. Fluid flow rate versus diameter is investigated, and discrepancy was observed in the results. Its non-monotonic behavior is reported and attributed to diameter-dependent potential energy landscape in CNT. Effects of CNT length and pressure difference on flow rate as well as radial distribution function were examined as an additional check to ensure that the physical behavior of the model is correct. The deviation of fluid atoms from the minimum point in potential function is found to be significantly effective on the fluid-solid friction force experienced by fluid atoms, and consequently on the flow rate values. Also, investigating short periods of time shows that fluid atoms move discontinuously in the course of their passage through CNT. Consequently, distribution of atoms shows certain dense spots, similar to peaks in radial distribution which is well known and examined in the previous literature. Extremely low flow rate in some cases of CNT diameter and chirality shows that care should be taken in designing novel nanoscale devices which are built based on fluid flow and its properties in CNTs.

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