Abstract
We construct mathematical models for the flow of sugarcane and juice througha sugar diffuser. The models describe how the concentration of sugar in thejuice increases during the process. The flow through the sugar cane in thediffuser is analysed. The injection of tracer on one of the jets is studied. Thediffusivity of the tracer is different for the direction of flow and across the flow.Our model is able to reproduce the behaviour observed in tracer experiments.A cavitation mechanism is investigated for creating dry regions in voids in thesugar cane. We show that voids occur when the permeability varies with depthin a way to produce regions of negative pressure. Their existence depends onthe variation in the permeability through the whole depth but especially onregions of low permeability away from the bottom of the bed.