Viscous flow phenomena in a partially filled rotor–stator system

Abstract

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.

Investigation of viscous flow phenomena in a rotating system

“…By the variation of Λ and F different flow phenomena in the system can be achieved [1,2]. In this part of the study we focus just on the left chamber, where a greater diversity of flow states can be observed.…”

“…In the second case the remaining space is filled with air as a passive phase. Depending on the settings in the system, which are the rotational speed of the drum, material properties of the liquid and the volume ratio of the two phases, different flow phenomena can be observed [1,2]. For the characterization of the flow dimensionless ratios given by the Reynolds number Re, the Froude number F r, the Capillary number Ca and the volumetric filling degree F are used.…”

Characterization of patterns in rimming flow

“…When a wider variety of cases than the present low-volume fraction regime are considered, there have been many studies in the literature [13][14][15]. As noted below, they show the richness of rimming flow with respect to rotation speed, various filling fractions and fluid phase used.…”

Stress analysis for a cavity flow of a memory fluid

“…1. Originally, we used the system to study free-surface phenomena if the equipment was partially filled with the liquid [7,39]. In the present context, the right chamber is completely filled with a highly viscous memory fluid.…”