A hybrid Monte Carlo-discrete ordinates method for phonon transport in micro/nanosystems with rough interfaces

Abstract

In recent years, the rapid development of micro/nanosystems raises the demand of thermal optimization of the new designs, and thus the accurate and efficient prediction of phonon transport in mesoscopic systems with complex interfaces is required. This work proposes a hybrid Monte Carlo-discrete ordinates method (MC-DOM) for steady-state phonon transport in such systems by developing an algorithm to exchange information between MC and DOM subdomains. Based on the phonon Boltzmann transport equation which is physically compatible with the system scale, our formulation exploits the computational efficiency of DOM in the bulk region with flexibility of MC near complex interfaces. The cross-plane phonon transport through the thin films is considered first as the benchmark for method verification, whose results agree well with those calculated by numerical and analytical solutions. It is noteworthy that compared to MC as a pure particle method, the hybrid method runs faster over a hundred of times for the temperature calculation when high-precision results are needed. The hybrid method is then applied to simulate the in-plane phonon transport through the double-layer thin films with rough interfaces. It is found that for rectangular interfaces with different roughness, the interfaces perpendicular to the heat flux will cause a larger thermal resistance than the parallel ones. Our hybrid method enriches numerical tools for mesoscopic phonon transport simulation, and is helpful to reveal the mechanisms behind and optimize the heat transport in micro/nanosystems with complex geometries.