MOLECULAR DYANMICS SIMULATION OF THE VISCOUSITIES OF THE QUANTUM FLUID HELIUM

摘要

This paper presents the detailed MD simulation on the viscosities of the quantum fluid helium at different temperatures and densities. The kinematic viscosities of helium are calculated from the expression describing the relationship between the shearing stress and velocity distributions flowing in the nano-channel. Two molecular systems with different size, L-J potential and the quadratic Feynman–Hibbs (QFH) potential functions are used to perform the MD simulation. All calculation results showed that the L-J model is not quantitatively correct for the supercritical and liquid helium, thereby the quantum effect must be taken into account when the quantum fluid helium is studied. The simulation processes supplemented by quantum effect corrections show that one must adopt very small external force, in order to avoid obvious effects on the system temperature distributions. However, such a small force increases greatly the calculation time, by the fact of 10, to achieve the steady state. The MD simulations are also indicated that the quantum effect correction becomes stronger with the decreasing of helium temperatures.