Deviations of the results for the properties of a dense hard-sphere gas near the walls of a micro channel using the hybrid molecular dynamics - Monte Carlo simulation method

摘要

We study the deviations for the results of the properties of a hard-sphere gas near the walls of a microano channel using the hybrid MD-MC simulation method compared to the pure MD and MC results. Our model for the micro channel consists of two parallel infinite plates situated at distance L apart from each other, and of gas molecules Confined between these two walls. We study the dependence of the deviations for higher densities, considering different lengths of the different simulation domains in the hybrid MD-MC method. We find that when density is increased, the deviations in the pure MC results are increasing compared to pure MD results. The deviations in the hybrid simulation results are decreasing and are very small when increasing the width of the solid-gas interface. The deviations of the pure MC simulation results from the pure MD simulation results for the number density are found to be around 0.9%, when the reduced density η = 0.1 and the width of the channel L = 50λ, where λ is the mean free path. When the hybrid method is used, the deviations are decreasing with a factor from two to three, and are between 0.32%-0.42%. For more dense gas (η = 0.2), the deviations of the MC simulation results for the number density are found to be 1.71%, and the deviations of the hybrid MD-MC simulation results between 0.246% and 0.6977%. We discuss how these deviations in case of a dense gas (η = 0.2) depend on the width of the interface, and we study it for the case when the MD domain is 10% and MC domain is 90% from the simulation domain, and also for the case when the MD domain is 50% and MC domain 50% from the whole simulation domain. For more dilute gas, the MC, MD and hybrid MC-MD simulations are in very good agreement and the deviations are negligible.