The free-surface flow of fully melted material in the conveying section of a co-rotating twin screw extruder has been simulated numerically with the Finite Volume Method and an Eulerian multiphase model. In this model the interface is captured in an implicit manner with the help of the local volume fraction in a cell.The results presented here reveal the power and conveying characteristics of the twin screw configuration. Some interesting findings are discussed for the power characteristic in the fully filled state as well. The flow field and derived quantities are discussed with regards to the axial transport, symmetries in the flow field and locations of high energy dissipation. All results are compared to the fully filled state.Additionally, a new term, the volume flux based "conveying degree", is introduced in this paper. The difference to the volume-based degree of fill is pointed out.

This paper deals with free-surface flows in a geometrically simple apparatus consisting of a rotating cylindrical drum with horizontal axis and a fixed internal plate. The drum is partially filled with a very viscous, optically transparent liquid and is otherwise filled with air as a passive phase. Due to the rotation some liquid mass is dragged upwards along the moving wall, scraped off by the fixed plate and forced to fall back into the liquid pool due to gravity. The resulting flow and the shape of the phase interface are visualised within a plane perpendicular to the cylinders axis. Different flow phenomena are detected, depending on the volumetric filling degree F and on the dimensionless parameter = g R/(ν ), which quantifies the relative influence of gravitational and viscous forces. Extended lubrication theories are used in order to model the shape of the phase interphase and to predict the conditions under which inner film flows may be expected. Some findings are validated by results of a more sophisticated numerical free-surface-flow simulation.

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