Abstract: Wall slip and viscous dissipation are two main scale effects in 3DP (Three dimensional printing) process, which has influences on the material's flow properties and thermophysical properties and the printing quality. According to the two phenomena above, theoretic models of wall slip and viscous dissipation were established, respectively, and the software Polyflow was used to study the two scale effects and their interactions with molten ABS in micro-tubes of different radius. Simulation results show that wall slip level increases with the slip coefficient decreasing, and material's velocity decreases with the increase of tube radius; Viscous dissipation level decreases with inlet temperature rising and tube radius decreasing. Furthermore, material's temperature in wall considering wall slip is lower than that without wall slip, and both wall slip and viscous dissipation level decrease when the inlet temperature rises.

Key words: 3DP, wall slip, viscous dissipation, modeling, numerical simulation