SIMULATION OF HEAT TRANSFER IN NANOSCALE FLOW USING MOLECULAR DYNAMICS

摘要

We investigate heat transfer between parallel plates separated by liquid argon using two-dimensional molecular dynamics (MD) simulations incorporating with 6-12 Lennard-Jones potential between molecule pairs. In molecular dynamics simulation of nanoscale flows through nanochannels, it is customary to fix the wall molecules. However, this approach cannot suitably model the heat transfer between the fluid molecules and wall molecules. Alternatively, we use thermal walls constructed from the oscillating molecules, which are connected to their original positions using linear spring forces. This approach is much more effective than the one which uses a fixed lattice wall modeling to simulate the heat transfer between wall and fluid. We implement this idea in analyzing the heat transfer in a few cases, including the shear driven and poiseuille flow with specified heat flux boundary conditions. In this method, the work done by the viscous stress (in case of shear driven flow) and the force applied to the fluid molecules (in case of poiseuille flow) produce heat in the fluid, which is dissipated from the nanochannel walls. We present the velocity profiles and temperature distributions for the both chosen test cases. As a result of interaction between the fluid molecules and their adjacent wall molecules, we can clearly observe the velocity slip in the velocity profiles and the temperature jump in the cross-sectional temperature distributions.