Abstract
We construct mathematical models for the flow of sugarcane and juice through a sugar diffuser. The models describe how the concentration of sugar in the juice increases during the process. The flow through the sugar cane in the diffuser is analysed. The injection of tracer on one of the jets is studied. The diffusivity 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 the sugar cane. We show that voids occur when the permeability varies with depth in a way to produce regions of negative pressure. Their existence depends on the variation in the permeability through the whole depth but especially on regions of low permeability away from the bottom of the bed.