분자동역학을 이용한 나노스케일 인터페이스 열전달의 치수효과 연구

Abstract

Heat has important role in many systems, such as fabrication process and power source. Together with the importance of heat, miniaturizing has made people interested in heat transfer at nanoscale. As system size reduces more and more, dominant effects are changed, and due to this change, continuum descriptions cannot describe the behavior at nanoscale. This phenomenon can be called as size effect. Kapitza resistance has important role in heat transfer at nanoscale interface, and it can be defined as kapitza length. In heat transfer at nanoscale interface, layering at near interface and temperature jump at interface are observed. In this thesis, size effect in heat transfer at nanoscale interface was investigated by using molecular dynamics (MD) simulations. Liquid argon confined between solid walls was conducted by NEMD simulations. Firstly, investigation of periodic boundary condition (PBC) and the effect of interaction strength were conducted. Number density profile, temperature profile, and heat flux were shown to clarify the effect of periodic boundary condition and the effect of solid-liquid LJ interaction strength. And then, we performed investigation of size effect in heat transfer at nanoscale interface. We showed density profile and temperature profile as the length of fluid region. And temperature gradient and heat flux result were shown, and from these result, we calculated thermal conductivity. Also, we calculated temperature jump at interface from temperature profile, and we calculated kapitza length and the ratio between kapitza length and the length of fluid region. As the length of fluid region increases, temperature gradient, heat flux, and average temperature jump gradually decrease. On the other hand, kapitza length is independent to length of fluid region. Thermal conductivity calculated by MD shows good agreement with experimental values. The ratio between kapitza length and the length of fluid region decreases as the length of fluid region increases.