In class we solved a flow through a cylindrical channel. Another important flow used in processing (predominately polymer processing) is flow through an annulus region. An annulus is defined as a gap between two concentric cylinders, see Figure. The inner cylinder is a solid with radius R and the outer is hollow with a radius R. You will usually encounter this in your reading and experience as "flow through a circular die", which would be used to form a plastic tube or pipe from a thermoplastic such as polyethylene. In a "die" of length L, a pressure drop across the annulus channel drives the fluid through the channel. a.) Determine the velocity profile through the annular space as a function of pressure gradient? b.) Determine the volumetric flowrate through the annulus? OUTER WALL INLET Fluid R1 R OUTLET axis of symmetry