Experimental Study of Fiber Interaction with a Cylinder Array
In papermaking, a slurry of wood fibres, which are approximately 2 millimetres long and 30 microns in diameter, is drained through a forming fabric. In this drainage process the fibres get trapped by the fabric as the water drains through it. The actual drainage process is obviously highly complicated because the forming fabric geometry is complex, the wood fibres may interact with one another, and the wood fibres have variable properties. However, we may gain some understanding of dewatering by considering simplified versions of the process.
A first simplification of the process is to consider only highly dilute suspensions of fibres in water (or in the limit, only individual fibres in water), for which interfibre forces are negligible. A further simplification of dewatering is to replace the three-dimensional forming fabric with a simple linear array of cylinders. A final simplification is to replace the highly variable wood fibres with more uniform fibres, such as nylon fibres. In summary, we are interested in the interaction of a nylon fibre with an array of cylinders, as water flows through the cylinders. The geometry is shown in Figure 1 below. A high speed video camera will be used to capture the fibre motion as it forced by the flowing water onto the cylinder array. For some fibre geometries and flow speeds the cylinder array is expected to trap the fibre, whereas for other geometries and speeds the fibre will slip off the array.
The Globalink student will assist a graduate student in developing the apparatus shown in Figure 1. He/she will then conduct experiments on fibres of varying lengths, diameters, mechanical properties and will develop a correlation to predict fibre trapping as a function of the relevant non-dimensional variables.